ML17219A545

Annual Environ Operating Rept,1986.

ML17219A545
Person / Time
Site:	Saint Lucie
Issue date:	12/31/1986
From:	APPLIED BIOLOGY, INC.
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ML17219A543	List: ML17219A542 ML17219A544 ML17219A545
References
AB-579, NUDOCS 8705010129
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'APPLIED BIOLOGY, INC. AB-679 0

FLGFIIDA PGWEFI S. LIGHT CGMPANY

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ENVIRQNMENTAL GPERATING REPGRT 870S010129 8704P7 PDR ADOCK OS000389 PDR 2968A NORTH DECATUR ROAD ~ ATLANTA,GEORGIA 30033 ~ 404-296-3900

AB-579 FLORIDA POWER 5 LIGHT COMPANY ST. LUCIE UNIT 2

'NNUAL ENVIRONMENTAL OPERATING REPORT 1986 APRIL 1987 FLORIDA POWER 5 LIGHT COMPANY JUNO BEACH, FLORIDA APPLIED BIOLOGY, INC.

ATLANTA, GEORGIA

'NVIRONMENTAL OPERATING REPORT TABLE OF CONTENTS

~Pa e TABLE Of CONVERSION FACTORS FOR METRIC UNITS EXECUTIVE

SUMMARY

lv Introduction- lv Turtle Nesting Survey \<<<<<<<< lv Intake Canal Monitoring V Other Related Activities V INTRODUCTION ----- - ---<<---- 1 Background- 1 Area Description - -

Plant Description -- 3 4

T URTLES I ntroductlon -

- 6 8

Materials and Methods >> 11 t Survey N estlng - <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\>> 11 Intake Canal Monitoring >><<<<<<<<>>>><<<<>><<<<<<<<>> 12 Studies to Evaluate and/or Mitigate Intake Entrapment - 15 Light Screen to Minimize Turtle Disorientation - - 15 Results and Discussion - 15 N estjng Survey <<<<<<<<<<>><<<<<<>><<<<<<>>>><<>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>><<<<<<>><<<<<<<<>>>> 15 Distribution of Nests Within the Nine 1.25-Km-Long S urvey Areas ;15 Distribution of Nests Along the Entire Island (1981<<1986) 20 Number of Nests and Population Estimates 23 Temporal Nesting Patterns 26 Predation on Turtle Nests <<<<<<<<<<<<<<<<<<<<>><<<<>> 27 Green and Leatherback Turtle Nesting 29 Intake Canal Monitoring <<<<<<<<<<>><<<<<<<<<<<<>> <<>><<>><<<<>> 31 Species Number and Temporal Distribution 32 Size-Class Distributions << 34 S Ratios <<<<<<>><<<<<< << <<<<>><< << >> 36 Capture Efficiencies- 38 Relative Condition 40 Mortalities >><<<<<<>><<<<<<<<<<<< 44 Recapture Incidents- <<<<<<<<<<<<<<>><<<<<<<<<<<<<<<<>><<>>>> 50 S ummary - -- - - - 52 LITERATURE CITED 57 FIGURES TABLES- 87

TABLE OF CONVERSION FACTORS FOR METRIC UNITS To convert jul ti ply by To obtain centigrade (degrees) ('C x 1.8) + 32 fahrenheit (degrees) centigrade (degrees) C + 273.18 kelvin (degrees) centimeters (cm) 3.937 x 10 1 inches centimeters (cm) 3.281 x 10 feet centimeters/second (cm/sec) 3.281 x 10-2 feet per second cubic centimeters (cm3) 1.0 x 10 liters grams (g) 2.205 x 10" pounds 3.527 x 10"2

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grams (g) ounces (avoirdupois) hectares (ha) 2. 471 acres kilograms (kg) 1.0 x 103 grams

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kilograms (kg) 2.2046 pounds kilograms (kg) 3 '274 x 101 ounces (avoi rdupois) t kilometers (km) 6.214 x 10 1 miles (statute) kilometers (km) 1.0 x 10 mi 1 l imeters liters (1) . 1.0 x 10 cubic centimeters (cm3) liters (1) 2.642 x 10 gallons (U.S. liquid) 1 meters (m). 3.281 feet r <

meters (m) 3.937 x 10 inches 1'

meters (m) 1.094 yards microns (p) 1.0 x 10-6 meters mil ligrams (mg) 1.0 x 10"3 grams 1 milligrams/liter (mg/1) 1.0 parts per million mil lili ters (ml ) 1.0 x 10"3 liters (U.S. liquid) millimeters (mm) 3.937 x 10"2 inches millimeters (mm) 3.281 x 10 feet square centimeters (cm2) 1.550 x 10" square inches square meters (m2) 1.076 x 101 square feet square mil limeters (mm2) 1.55 x 103 square inches

EXECUTIVE

SUMMARY

INTRODUCTION The St. Lucie Plant is an electric generating station on Hutchinson I

Island in St. Lucie County, Florida. The plant consists of two nuclear-fueled 850-Sf units; Unit 1 was placed on-line in March 1976 and Unit 2 in Nay 1983. This document has been prepared to satisfy the requirements contained in the United States Nuclear Regulatory Commission's Appendix B Environmental Protecti on. Pl an (EPP) to St. Luci e Uni t 2 Facil i ty C

Operating License No. NPF-16. This report'iscusses environmental pro-tection activities related to sea turtles as required by Subsection 4.2 of the EPP.

TURTLE NESTING SURVEY There have been considerable year-to-year fluctuations in sea turtle nesting activity on Hutchinson Island since monitoring began in 1971.

Low nesting activity in 1975 and 1981 - 1983 in the vicinity of the power plant was attributed to construction of plant intake and discharge struc-tures. Nesting returned to normal or above normal levels following both periods of construction. Nesting data through 1986 have shown no long-term reductions in total nesting, total emergences or nesting success.

No telationship between total nesting on the island and power plant operation was indicated.

INTAKE CANAL MONITORING Since plant operation began in 1976, 1,530 sea turtles (including 71 recaptures) representing five different species have been removed from the intake canal . Eighty-six percent of these were 1 og gerheads.

Differences in the numbers of turtles found during different months and years were attributed to natural variation in the occurrences of turtles in the vicinity of the plant, rather than to arp influence of the plant itself. The majority (about 92 percent) of the turtles removed from the intake canal were captured alive and released back into the ocean.

Turtles confined between the A1A barrier net and intake headwalls usually t

resided in the canal for a relatively short period of time and most were in good to excellent condition when caught. The cause of death for most canal mortalities could not be accurately determined. However,. probable causes were assigned when possible and corrective measures taken to mini-mize future mortalities.

OTHER RELATED ACTIYITIES The integrity of a vegetative light screen along the dune line at the St. Lucie Plant is assessed on a yearly basis. During 1986, periodic inspections of the screen were made and replantings conducted on an as needed basis. As required by the NRC's Unit 2 Environmental Protection Plan, studies to evaluate various intake deterrent systems were conducted during 1982 and 1983. Results and evaluations of those studies were pre-sented to regulatory agenci es during 1984, and the requirement is. now

INTRODUCTION BACKGROUND This document has been prepared to satisfy the requirements con-tained in the United States Nuclear Regulatory Commission's (NRC)

Appendix B Environmental Protection Plan to St. Lucie Unit 2 Facility Operating License No. NPF-16.

In 1970, Florida Power 5 Light Company (FPL) was issued Permit No.

CPPR-74 by the United States Atomic Energy Commission, now the Nuclear Regulatory Commission, that allowed construction of Unit 1 of the St.

Luci e Plant, an 850-HW nuclear-powered electric generating station on Hutchinson Island in St. Lucie County, Florida. St. Lucie Plant Unit 1 was placed on-line in Harch 1976. In Hay 1977, FPL was issued Permit No.

CPPR-144 by the NRC for the construction of a second 850-HW nuclear-powered unit. Unit 2 was placed on-line in Hay 1983 and began commercial operation in August of that year.

St. Lucie Plant Units 1 and 2 use the Atlantic Ocean as a source of water'or once-through condenser cooling. Since 1971, the potential environmental effects resulting from the intake and discharge of this water have been the subject of FPL-sponsored biotic studies at .the site.

Baseline environmental studies of the marine environment adjacent to the St. Lucie Plant were described in a series of reports published by the Florida Department of Natural Resources (Camp et al., 1977; Futch and Dwinell, 1977; Gallagher, 1977; Gallagher and Hollinger, 1977; Worth and Hollinger, 1977; Moffler and Van Breedveld, 1979; Tester and Steidinger, 1979; Walker 1979; Walker et al., 1979; Walker and Steidinger, 1979).

The results of Unit 1 operational and Unit 2 preoperational biotic moni-toring at the St. Lucie Plant were presented in six annual reports (ABI',

1977, 1978, 1979, 1980a, 198lb, 1982) . In January 1982, a National Pollutant Discharge Elimination System (NPDES)= permit was issued to FPL by the U.S. Environmental Protection Agency (EPA). The EPA guidelines for the St. Luci e site biological studies were based on the document entitled "Proposed St. Lucie Plant Preoperational and Operational Biological Monitoring Program - August 1981" (ABI, 198lc). Findings from these studies were reported in three annual reports (ABI, 1983, 1984a, 1985a). The EPA biotic monitoring requirements were deleted in 1985.

Jurisdiction for sea turtle studies is with the NRC, which is con-sidered to be the lead federal agency relative to consultation under the Endangered Species Act. Previous results dealing exClusively with sea turtl e studi es are contained in three envi ronmental operating reports (ABI, 1984b, 1985b, 1986). This report describes the 1986 environmental protection activities related to sea turtles, as required by Subsection 4.2 of the St. Luci e Plant Unit 2 Environmental Protection Plan.

AREA DESCRIPTION The St. Lucie, Plant is located on a 457-ha site on Hutchinson Island on Florida's east coast (Figures I and 2). The plant is approximately midway between the Ft. Pierce and St. Lucie Inlets. It is bounded on its east side by the Atlantic Ocean and on its west side by the Indian River Lagoon.

Hutchinson Island is a barrier island that extends 36 km between inlets and obtains its maximum width of 2 km at the plant site. Eleva-tions approach 5 m atop dunes bordering the beach and decrease to sea level i'n the mangrove swamps that are common on much of the western side.

Island vegetation is typical of southeastern Florida coastal areas; dense stands of Australian pine, palmetto, sea grape and Spanish bayonet are present a% the higher elevations, and mangroves abound at the lower ele-vations. Large stands of black mangroves, including some on the plant site, have been killed by flooding for mosquito control over past decades.

h The Atlantic shoreline of Hutchinson Island is composed of sand and shell hash with intermittent rocky promontories protruding through the beach face along the southern end of the island. Submerged coquinoid rock formations parallel much of the island off the ocean beaches. The ocean bottom immedi ately offshore from the plant site consists primarily of sand and shell sediments. The unstable substrate limits the establishment of rooted macrophytes.'

The Florida Current, which flows parallel to the continental shelf margin, begins to diverge from the coastline at West palm Beach. At Hutchinson Island, the current is approximately 33 km offshore.

Oceanic'ater associated with the western boundary of the current periodically meanders over the inner shelf, especially during summer months.

PLANT DESCRIPTION The St. Lucie Plant consists of two 850-HW nuclear-fueled electric generating units that use nearshore ocean waters for the plant's once through condenser cooling water system. Water for the pl ant enters through three submerged intake structures located about 365 m offshore (Figure 2). Each of the intake structures is equipped with a velocity cap to minimize fish entrapment. Horizontal intake velocities are less than 30 cm/sec. From the intake structures, the water passes through submerged pipes (two 3.7 m and one 4.9 m in di,ameter) under the beach and dunes that lead to a 1500-m long intake canal. This canal transports, the water to the plant. After passing through the plant, the heated water is discharged into a 670m long canal that leads to two buried discharge pipelines. .These pass underneath the dunes and beach and along the ocean floor to the submerged discharges, the first of which is approximately 365 m offshore and 730 m north of the intake.

Heated water leaves the first discharge line from a Y-shaped nozzle (diffuser) at a design velocity of 396 cm/sec. This high-momentum jet entrains ambient water resulting in rapid heat dissipation. The ocean depth in the area of the first discharge is about 6 m. Heated water

leaves the second discharge line through a series of 48 equally spaced high velocity jets along a 323-m manifold (multiport di ffuser). This diffuser starts 168 m beyond the first discharge and terminates 856 m from shore'. The ocean~ depth at discharge along this diffuser is from about 10 to 12 m. As with the first diffuser, the purpose of the second diffuser is to entrain ambient water and rapidly dissipate heat. From the points of discharge at both diffusers, the warmer water rises to the surface and forms a surface plume of heated water. The plume then spreads out on the surface of the ocean under the influence of wind and currents and the heat dissipates to the atmosphere.

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TURTLES The NRC's St. Lucie Unit 2 Appendix B Environmental Protection Plan issued April 1983 contains the following technical specifications:

4.2 Terrestrial/A uatic Issues Issues on endangered or threatened sea turtles raised in the Unit 2 FES-OL fNRC, 1982j and in the Endangered Species Biological Assessment (Narch 1982) fBellmund et al., 19823 will be addressed by programs as follows:

4.2.1 Beach Nestin Surve s Beach nesting surveys for all species of sea turtles will be conducted on a yearly basis for the period of I'982 through 1986. These surveys will be con-ducted during the nesting season from approximately mid-April through August.

The Hutchinson Island beach will be divided into 36 one-km-long survey areas. In addition, the nine 1.25-km-long survey areas used in previous studies (1971-1979) will be maintained for comparison pur-poses. Survey areas will be marked with numbered wooden plaques and/or existing landmarks.

The entire beach will be surveyed seven days a week.

All new nests and false crawls will be counted and recorded in each area. After counting, all crawl tracks will be obli terated to avoid recounting.

Predation on nests by raccoons or other predators will be recorded as it occurs. Records will be kept of any seasonal changes in beach topography that may affect the suitability of the beach for nesting.

4.2.2 Studies to Evaluate and/or Miti ate Intake A program that employs light and/or sound to deter turtles from the intake structure will be conducted.

The study will determine with laboratory and field experiments if sound and/or light will result in a reduction of total turtle entrapment rate.

The study shall be implemented no later than after the final removal from the ocean of equipment and

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structures associated with construction of the third intake structure and the experiments shall terminate 18 months later. Four months after the conclusion of the experimental period, a report on the results of the study will be submitted to NRC, EPA, National Marine Fisheries Service (NHFS}, and the U.S. Fish and Wildlife Service (USFWS} for their evaluation.

If a statistically significant reduction in annual total turtle entrapment rate of 80 percent or greater can be demonstrated, using the developed technology and upon FPL receiving written con-currence by NRC, EPA, NMFS, and USFWS then permanent installation of the deterrent system shall be completed and functioning no later than 18 months after the agencies'oncurrence. The design of this study needs to take into account the significant annual variation in turtle entrapment observed in the past.

If an 80 percent reduction of turtle entrapment can-riot be projected to all three intake structures, then an interagency task force composed of NRC, EPA, NMFS, USFWS, .and FPL shall convene 18 months after completion of the Shird intake and determine if other courses of action to mi-tigate and/or reduce turtle entrapment are warranted (such as physical barrier, emergence of new technology or methods to deter turtles).

4.2.3 Studies to Evaluate and/or Miti ate Intake Alternative methods or procedures for the capture of sea turtles entrapped in the intake canal will be evaluated. If a method or procedure is considered feasible and cost effective and may reduce capture mortality rates, it will be field tested in the i ntake canal.

4.2.4 Li ht Screen to Minimize Turtle Disorienta-tion [NOTE:. This is also Section 4.2 of the NRC St.

Lucie Unit I Appendix B Technical Specifications issued May 19823 Australian pine or other suitable plants (i.e.,

native vegetation such as live oak, native figs, wild tamarine and others) shall be planted and main-tained as a light screen, along the beach dune line bordering the plant property, to minimize turtle disorientation.

4.2.5 Ca ture and Release Pro ram Sea turtle removal from the intake canal will be conducted on a continuing basis. The turtles will be captured with large mesh nets, or other suitable nondestructive device(s), if deemed appropriate.

formalized daily inspection, from the shoreline, of A

the capture device(s) will be made by a qualified individual when the device(s) are deployed. The turtles wi 11 be identified to species, measured, weighed {if appropriate), tagged and released back into the ocean. Records of wounds, fresh or old, and a subjective judgement on the condition of the turtle (e.g., barnacle coverage, underweight) will be maintained. Methods of obtaining additional biological/physiological data, such as blood analy-ses and parasite loads, from captured sea turtles will be pursued. Dead sea turtles will be subjected to a gross necropsy, if found in fresh condition.

INTRODUCTION e Hutchinson Island, Florida, loggerhead turtle, Caretta caretta, Atlantic green turtle, .Chelnnia is an and important rookery

~mdas, also supports and the some for the Atlantic nesting of the leatherback turtle,

~oh 1 i (C 1d 11 1., 1959; R . )968; 8 11 gh al., 1972; Worth and Smith, 1976; Williams-Walls et al., 1983). All three species are protected by state and federal statutes. The federal government classifies the loggerhead turtle as a threatened species. The leatherback turtle and the Florida nesting population of the green turtle are listed by the federal government as endangered species. Because of reductions in world populations of marine turtles resulting from coastal development and fishing pressure (NMFS, 1978), maintaining the vitality of the Hutchinson Island rookery is important.

It has been a prime concern of FPL that the construction and sub-sequent operation of the St. Lucie Plant would not adversely affect the Hutchinson Island rookery. Because of this concern, FPL has sponsored monitoring of marine turtle nesting activity on the island since 1971.

Daytime surveys to quantify nesting, as well as nighttime turtle tagging programs, were conducted in odd numbered years from 1971 through 1979. During daytime nesting surveys, nine 1.25-km-long survey areas C

were monitored five days per week. The St. Lucie Plant began operation in 1976; therefore, the first three survey years (1971, 1973 and 1975) t were preoperational. Though the power plant was not operating during 1975, St. Lucie Plant Unit Ho. 1 ocean intake and discharge structures were installed during that year. Installation of these structures included construction activities conducted offshore from and perpen-dicular to the beach. Construction activity had been completed and the plant was in full operation during the 1977 and 1979 surveys.

A modified daytime nesting survey was conducted in 1980 during the preliminary construction of the ocean discharge structure for St. Lucie Plant Unit 2. During this study, four of the previously established 1.25-km-long survey areas were monitored. Additionally, eggs from turtle nests potentially endangered by construction activities were relocated.

Every year from 1981 through 1986, thirty-six 1-km-long survey areas comprising the entire island were monitored seven days a week during the nesting season. The St. Lucie Plant Unit Ho. 2 discharge structure was

tion of the Unit 2 intake structure e proceeded throughout the 1982 nesting season and was completed near the end of the 1983 season. Construction activities associated with installation of both structures were similar to those conducted when Unit 1 intake and discharge structures were installed. Eggs from turtle nests potentially endangered by construction activities were relocated during all three years.

In addition to monitoring sea turtle nesting activities and relo-cating nests away from plant construction areas, monitoring of turtles in the intake canal has been an integral part of the St. Lucie Plant

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environmental monitoring program. Turtles entering the ocean intake structures are rapidly transported with cooling water through the intake

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pipes and into the enclosed canal system where they are entrapped. Since the plant became operational in 1976, turtles entrapped in the intake canal have been captured, measured, tagged and returned alive to the ocean.

Previous publications and technical reports have presented results of the nesting surveys and nest relocation activities (Gallagher et al.,

1972; Worth and Smith, 1976; ABI, 1978, 1980a, 1981a, 1982, 1983, 1984b, 1985b, 1986; Williams-Walls et al., 1983; Proffitt et al., 1986), docu-mented studies on the potential effects of thermal discharges on hatch-l ing swimming speed (ABI, 1978; O'ara, 1980), and di scussed the significance of data generated by the canal capture program (Ernest et al., in press). The purpose of this report is to 1) pr esent 1986 sea 10

turtle nesting survey data and summarize observed spatial and temporal trends in nesting .activities since 1971, 2) document and summarize pre-dation on turtle nests since 1971, and 3) present results of intake canal monitoring conducted during 1986 and summarize canal capture data since 1976.

MATERIALS AND METHODS Nesti n Surve Methodol ogi es used during previ ous turtl e nesting surveys on Hutchinson Island were described by Gallagher et al. (1972), Worth and jf

'I Smi th (1976) and ABI (1978, 1980a, 1981a, 1982, 1983, 1984b, 1985b, I

1986). Methods used during the 1986 survey were designed to allow com-parisons with these previous studies, From 16 April through 23 April 1986, preliminary nest surveys were conducted every two to thr ee days along Hutchinson Island from Ft.

Pierce Inlet south to St. Lucie Inlet. After 23 April, surveys were con-ducted daily through 12 September. Several additional surveys were con-ducted after 12 September to confirm that nesting had ceased. Biologists used small off-road motorcycles to survey the island each morning. New nests, non-nesting emergences (false crawls), and nests destroyed by pre-E dators were recorded for each of the thirty-six 1-km-long survey areas comprising the entire island (Figure 3). The nine 1.25-km-long survey areas established by Gallagher et al. (1972) also were monitored so com-parisons could be made with previous studies.

During the daily nest monitoring, the beach was continually moni-tored to detect any major changes in topography that may have affected the beach's suitability for nesting. In addition, each of the thirty-six 1-km-long survey areas was systematically analyzed and categorized based on beach slope (steep, moderate, etc.), width from high tide line to the dune, presence of benches (areas of abrupt vert;ical relief) and miscella-neous characteristics (packed sand, scattered rock, vegetation on the beach, exposed roots on the primary dune, etc.).

In a cooperative effort, the Florida Department of Natural Resources (DNR) was notified of all green turtle nests. Eggs from some of these nests were collected as part of the Florida DNR Headstart Program.

Intake Canal Monitorin Routine capture of sea tur ties from the St. Lucie Plant intake canal continued during 1986. Turtles were removed from the canal with large-mesh nets fished between the intake headwalls and the barrier net located at the Highway A1A bridge (Figure 2). Nets were usually deployed on Monday morning and retrieved on Friday afternoon. To detect captures, formal daily inspections of the nets (mornings and afternoons) were made each day of deployment.

Various sizes, numbers and locations of nets have been used to date as capture techniques have been refined. Nets in recent use were from 32 to 61 m in length, 2.7 to 3.7 m in depth and 30 to 40 cm in stretch mesh.

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weighted with lead lines, turtles which became entangled remained at the water's surface until removed.

The barrier net at the A1A bridge is intended to confine turtles to the easternmost section of the intake canal, where fishing techniques have been most effective. However, the integrity of the barrier net occasionally has been compromised, and turtles have been able to. swim over or under the net. Additionally, turtles smaller than 30.5 cm in carapace width can swim through its large mesh. Individuals escaping capture in the turtle nets and circumventing the barrier net eventually emerged in the intake wells of Units l and 2 (Figure 2). Turtles entering the wells were retrieved by means of large mechanical rakes or specially designed nets. Personnel of Applied Biology, Inc. were on'call 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day to retrieve captured turtles from both the intake wells and turtle nets.

The utmost care was taken in handling captured turtles to prevent injury or trauma. After removal from the canal, turtles were identified to species, measured, weighed, tagged, examined for overall condition (wounds, abnormalities, parasites, etc.) and released back into the ocean. Although both straight-line and curved carapace lengths were measured, only straight-line measurements were used in analyses presented in this report. Straight-line carapace length (SLCL) was measured from the precentral scute to the notch between the postcentral scutes (minimum carapace length of Pritchard et al., 1983).

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Si nce 1982, bl ood sampl es have been col 1 ected and analyzed to investigate the potential occurrence and significance of anemia in these animals and to determine the sex of immature turtles.. Blood was removed from the paired dorsal cervical sinuses of subject turtles using the technique described by Owens and Ruiz (1980). A small subsample of whole blood was hemolyzed and hemoglobin measured in grams per 1OO ml by colorimetry using an A.O. 1010D hemoglobinometer. The remainder of the blood sample was centrifuged for 15 minutes to separate cells and serum.

Sex determinations were subsequently made by researchers at Texas A 5 H University using radioimmunoassay for serum testosterone (Owens et al.,

1978). Since 1984, blood cell samples have also been provided to the National Marine Fisheries Service for the purpose of developing and refining methods which will be used to conduct turtle stock analysis.

Sick or injured turtl es were treated and occasional ly held for observation prior to release. When treatment was warranted, injections of antibiotics and vitamins were administered by a local veterinarian.

Resuscitation techniques were used if a turtle was found that appeared to have died recently. Beginning in 1982, necropsies were conducted on dead turtles found in fresh condition; two animals, one green and one loggerhead, were found suitable for necropsy in 1986.

Florida Power 8 Light Company and Applied Biology, Inc. continued to assist other sea turtle researchers in 1986. In addition to the Florida DNR's Headstart Program, data, specimens and/or assistance have been given to the National Marine .Fisheries Services, U.S. Army Corps of r

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Resources Division, Texas A & M University, University of Rhode Island, University of South Carolina, University of Illinois and the Western Atlantic Turtle Symposium.

Studies to Evaluate and/or Mitigate Intake Entrapment A program that employs light and/or sound to deter turtles 'from entering the intake structures was conducted in 1982 and 1983 and completed in January 1984. As required by the specification, the .results and evaluations were written up and a presentation was made to the NRC, National Marine Fisheries Service and the Florida Department of Natural Resources on 11 April 1984. Requirement 4.2.2 of the NRC's St. Luci e e Unit 2 Appendix B Environmental Protection Plan is considered completed with submission of deterrent study findings.

Li ht Screen to Minimize Turtle Disorientation A vegetative beach dune light screen created to minimize turtle I

disorientation at the St. Lucie Plant was periodically inspected by FPL personnel during 1986. Replantings were conducted as required to main-tain its integrity.

RESULTS AND DISCUSSION Nestin Survey Distribution of Nests Within the Nine 1.25-km-ion Survey Areas Nest density has varied considerably within each study area from e

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year to year (Table 1). However, distribution of nest densities with 15

respect to the location of the nine survey areas has consistently shown a gradient of increasing nest density from north to south along the island (Figure 4). Nest densities were fairly uniform among the nine areas only in 1973. That year, Worth and Smith (1976) attributed this uniform nest distribution to beach accretion in Areas 1 through 3 (Figure 3). The strongest gradient observed corresponds with the severe erosion of the northern portion of the island in 1979 (Williams-Walls et al., 1983).

The changes in nest density gradients during periods of observed erosion and accretion indicate that these processes may influence the selection of nesting sites. by loggerhead turtles. However, during the last four years no consistent relationship was apparent when field observations of beach widths were compared to the distribution of nests along the island.

Additional factors, such as offshore bottom contours, spatial distribu-tion of nearshore reefs, type and extent of dune vegetation, C

and degree of human activity on the beach at night also may affect the spatial distribution of nests (Caldwell, 1962; Hendrickson and Balasingam, 1966; Bustard and Gr eenham, 1968; Hughes, 1974; Davis and Whiting, 1977; Mortimer, 1982). Furthermore, relationships between spatial distribu-tions of nests and environmental factors may be complicated by nest site tenacity of nesting turtles. Schulz (1975) suggested that nest site

'tenacity forces turtles to maintain their nesting site as long as possible, even though those sites may be undergoing changes.

Not all ventures onto the beach by a female turtle culminate in suc-cessful nests. These "false crawls" (non-nesting emergences) may occur e for many reasons and are commonly encountered at other rookeries (Baldwin 16

and Lofton, 1959; Schulz, 1975; Davis and Whiting, 1977; Talbert et al.,

1980; Raymond, 1984). Davis and Whiting (1977)'suggested that relatively high percentages of false crawls may reflect disturbances or unsatisfac-tory nesting beach characteristics. Therefore, certain factors may affect a turtle's preference to emerge on a beach, while other factors may affect a turtle's tendency to nest after it has emerged. An index which relates the number of nests deposited in an area to the number of false crawls in that area is useful in estimating the post-emergence suitability of that beach for nesting. In the present study this index is termed "nesting success" and is defined as the percentage of total emergences that result in nests.

The observed gradients of increasing nest densities from north -to south along the island were generally consistent with gradients of increasing .emergences from north to south (Table 2; Figure 5). In contrast, variations in nesting success (Table 3; Figure 6) along the island were not consistent with observed gradients of nest densities.

Therefore, greater nest densities along the southern portion of the island were primarily the result of more turtles coming ashore there rather than to more preferable nesting conditions being encountered by turtles after they emerged.

Hughes (1974) and Bustard (1968) found that loggerheads preferred beaches adjacent to outcrops of rocks or subtidal reefs. Williams-Walls et al. (1983) suggested that the nesting gradient on Hutchinson Island may be influenced by the offshore reefs if female turtles concentrate on 17

the reefs closest to the beach to rest or feed. Williams-Walls et al.

(1983) further stated that the proximity of offshore reefs would put the greatest concentrati on of turtles near the southern porti on of the island. Therefore, the apparent gradient in loggerhead emergences and nest densities may be influenced by nearshore reef distribution, as well as beach accretion and erosion.

Relatively low nest densities in Area 4 (adjacent to the power plant) appeared to be restricted to years of intake and discharge construction (Figure 3). In order to determine whether construction of power plant intake and discharge structures has had a significant effect on nesting adjacent to the St. Lucie Plant, nest densities in Area

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compared to nest densities in

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Area 5.~ Area 5 was chosen as a control because baseline nest densities in Area 5 were similar to those in

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Area 4 and because it was in proximity to Area 4 yet outside the area expected to be influenced by either power plant operation or intake/discharge construction.

Log-likelihood tests of independence (6-test; Sokal and Rohlf, 1981) were used to evaluate between-year differences in nesting activity be-tween the two sites. Comparison of baseline years (1971 and 1973) showed no significant (P<.05) di fference in numbers of nests between sites, indicating that the control site did indeed serve as a valid control.

Numbers of nests at plant and control sites were then evaluated between baseline years and 1) all years of construction (1975, 1981, 1982 and 1983), ') years of construction with plant operation (1981, 1982 and 1983), and 3) a year of plant construction without operation (1975).

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When all years of construction were compared, the plant site had significantly (P<.05) fewer nests than the control site. Furthermore, numbers of nests were significantly (P<.05) lower at the plant site than at the control site during both the construction year without operation and the construction years with operation.

Turtles are very sensitive to alarming stimuli just prior to emerging onto beaches (Schulz, 1975) and as they ascend beaches (Hirth, 1971). Among these alarming stimuli, moving lights will frighten nesting sea turtles of all species (Mortimer, 1982). Moving lights and other nocturnal activities associated with intake/discharge c0nstruction may have contributed to reduced emergences and, consequently, reduced nest densities relative to adjacent areas. However, nesting success values in Area 4 during construction years were not markedly different from those in Area 5.. Similar nesting success values between these two areas suggest that part of Area 4 was outside the influence of construction activities and that the turtles that emerged in Area 4 primarily emerged beyond the area influenced by construction activities. Though nest den-sities weie reduced in Area 4 during 1981, 1982 and 1983, they returned to normal or above normal levels after construction activities were completed, as was observed during years following construction in 1975.

A 6-test of independence also was used to determine if nest den-sities differed significantly before and after power plant operation (exclusive of intake/discharge construction). After excluding years during which intake/discharge construction occurred (1975, 1981, 1982 and 19

1983), nest densities in Areas 4 and 5 were compared between preopera-tional years (1971 and 1973) and operational years (1977, 1979, 1980, 1984, 1985 and 1986). When performed on cumulative data through 1985, the G-test indicated no significant (P<0.05) difference between preopera-tional and operational periods (ABI, 1986). However, when data for 1986 were included, test results indicated a significant difference between the two periods. Although Areas 4 and 5 both experienced record numbers of emergences during 1986 (Table 2), the number of nests resulting from those emergences was disproportionately higher in Area 4 (Tables 1 and 3). The deviation in the relative proportion of nests between the two t

areas apparently was of sufficient magnitude that when combined with pre-vious non-construction operational data produced results significantly different from those obtained during baseline years. However, as inferred by the data, differences in nesting patterns between baseline and operational years resulted primarily from less favorable nesting con-ditions in Area 5 (i.e., lower nesting success) rather than from any long-term decline in nesting resulting from power plant operation.

Data collected through 1986 have shown no long-term overall reduc-tions in nesting, total emergences or nesting success in the nine 1.25-km-long survey areas.

Distribution of Nests Alon the Entire Island 1981-1986 From 1981 through 1986, distributions of loggerhead turtle nest den-sities among the thirty-six 1-km-long survey areas comprising the entire island also showed a gradient of increasing densities from north to south 20

northern half of the island. No gradient was apparent south of Area S, and nest densities generally remained relatively high along the southern half of the island. The distribut>on of loggerhead turtle emergences among the thi rty-six survey areas followed the same general pattern as nest densities (Figure 8). Although differences in nesting succe'ss contributed to differences in nest densities in a number of instances, general patterns of nesting success were not consistent with general pat-terns'f nest densities (Figure 9). Thus, as was found for the nine 1.25-km-long survey areas, the distribution of nests along the island was t

primarily a result .of pre-emergent rather than post-emergent factors.

Our ing all six survey years (1981-1986), nest densities were lowest in Area A and increased substantially from north to south through Area E (Figure 7). Numbers of emergences in Areas A through E parallel this pattern of substantial increase from north to south (Figure 8). The pre-sence of deep water close to shore has been suggested as a factor which might influence sea turtles to emerge on particular beaches (Hendrickso'n and Balasingam, 1966; Mortimer, 1982). The distance from shore to the thirty-foot water depth contour continuously decreases from Area A through Area E. This may partially account for the observed pattern of increased emergences from north to south along this particular stretch of beach. Furthermore, large public beach accesses in Areas A through G, t

combined with considerable artificial lighting in those areas, provide the potential for extensive and highly visible human activity on the beach at night. As previously stated, turtles just prior to emerging 21

onto beaches are very sensitive to alarming stimuli, therefore, nighttime human activity in these areas may deter turtles from emerging. Human activity also may discourage turtles from nesting after they have emerged onto the beach, and may have contributed to the somewhat lower nesting success observed in Areas A through C during several years (Figure 9).

Low nesting success in Areas A and 8 from 1981 through 1984, following beach renourishment in 1980, also may be related to beach characteristics such as persistent and extensive areas of vertical relief (benches),

accumulations of rocks and shells, and compact sand in these areas.

Apparent'Iy, a combination of factors that affected both emergence and nesting success resulted in the extremely low nest densities along the northern four kilometers of the island.

Hest densities, numbers of emergences and, to a lesser extent, nesting success have remained relatively low in Area Z from 1981 through 1986. Since this area includes a large public beach access, a motel and considerable -artificial lighting, nocturnal human activity in this area may account for these relatively low values.

Relatively Iow nest densities, numbers of emergences and nesting success in Area 0 (Power Plant Site) during 1981, 1982 and 1983 were apparently associated with construction activities during the installa-tion of the St. Lucie Plant Unit Ho. 2 intake and discharge structures.

Reasons for reductions in nest densities and emergences during construc-tion activities have been discussed. During construction years, reduc-tions in nesting success

~ ~

were apparent in Area 0 though they were not 22

smaller than Area 4; therefore, a greater percentage of Area 0 was.within the influence of construction activities. During 1984, 1985 and 19&6, nest densities, numbers of emergences and nesting success in Area 0 were comparable to or higher than values for adjacent areas and apparently were not affected by power plant operation.

No long-term trend towards decreased nest densities, numbers of emergences or nesting success were indicated by data for the thirty-six 1-km-long survey areas.

Number of Nests and Po ulation Estimates Various methods were used during surveys prior to 1981 to estimate the total number of nests on Hutchinson 'sland, based on the number of nests found in the nine 1.25-km-long survey areas (Gallagher et al.,

1972; Worth and Smith, 1976; ABI, 1980a). Estimation methods can utilize either extrapolation. of the nine area total to the whole island or an estimate resulting from linear regression analysis. The latter method is based on the apparent linear relationship between nest densities in the nine study areas and their distance from Ft. Pierce Inlet. Since all nests on the entire island were counted from 1981 through 1986, the accuracy of estimation techniques can be determined for these six years.

\

The regression method overestimated the total number of nests on the island by 23 to 32 percent during the last six survey years (Table 4).

'23

apparent linear distribution of nests among the nine study areas and the actual curvilinear distribution of nests along the entire island (ABI, 1984b). The extrapolation method produced more accurate estimates of total nesting on the island. However, this method still overestimated total annual nesting by 6 to 11 percent during the last six years.

The extrapolation method was based on the assumption that the average nest density in the nine survey areas, which comprise 31.25 per-cent of the island's coastline, was equal to the average nest density for the entire island. Thus, total nesting could be calculated by mul t i plying the total number of nests in the nine areas by 3. 20.

However, results of surveys conducted from 1981 through 1986 indicate that the average annual nest densities in the nine areas were slightly higher than average nest densities for the entire island. From 1981 through 1986 the total number of nests in the nine areas varied from 33.1 to 34.8 percent (mean = 33.7 percent) of the total number of nests on the entire island. Therefore, estimates of the total number of nests on the island should be calculated by multiplying the number of nests in th' nine areas by 2.97 rather than 3.20. Corrected extrapolation estimates of total annual nesting on the island from 1981 through 1986 remained within four percent of the actual total number of nests recorded each year (Table 4). Because the proportion of nests, deposited in the nine areas remained relatively constant during all six years in which the entire island was surveyed, this method should provide a more accurate estimate of total nesting on the island than that previously obtained by a direct extrapolation

~

based on percentage of shoreline surveyed.

24

Regardless of the method used to estimate total nesting, it is clear that nesting activity on Hutchinson Island fluctuates considerably from year to year (Table 4). Year-to-year variations in nest densities also are common at other rookeries (Hughes, 1976; Davis and Whiting, 1977; Ehrhart, 1980) and may result from the overlapping of non-annual breeding populations. During the last five years, however, annual nest production has remained relatively high. Total nesting activity was greatest during 1986 when 5,483 loggerhead nests were recorded on the island. No rela-tionships between total nesting activity on the island and power plant operation or intake/discharge construction were indicated by year-to-year variations in total nesting on Hutchinson Island.

In order to determine the total number of female loggerhead turtles nesting on Hutchinson Island during a given season, an estimate of the number of nests produced by each female must be determined. A comparison of the number of nests produced by tagged turtles during the 1975, 1977 and 1979 surveys indicated that an average of two nests per female was produced during a nesting season (ABI, 1980a). Thus, estimates of the total numbers of females nesting during previous survey years may be obtained by dividing the calculated total number of nests by two. Based on cor rected extrapolation estimates of total nesting, the number of female loggerhead turtles nesting on Hutchinson Island varied from approximately 1,400 to 2,200 individuals during survey years 1971 through 1979. Based on whole-island nest counts, the estimated total number of nesting females varied from 1,558 to 2,742 individuals during survey 25

Temporal Nestin Patterns The loggerhead turtle nesting season usually begins in early May, when ocean temperatures reach 23 to 24 C, attains a maximum during June or July, and ends by late August or early September. Nesting activity du'ring 1986 followed this pattern (Figure 10). Shifts in the temporal nesting pattern on Hutchinson Island (Figure 11) may be influenced by fluctuations in water temperature. This was observed during 1975 and 1982 when early nesting in April coincided wi th average ocean tem-peratures above 24'C (ABI, 1983; Williams-Walls et al., 1983).

Cool water intrusions frequently occur of f southeastern Fl orida during the summer (Taylor and Stewart, 1958; Smith, 1982). Worth and Smith (1976), Williams-Walls et al. (1983) and ABI (1982, 1983, 1984b, 1985b, 1986) suggested that cool water intrusions may have been respon-sible for short-term reductions in loggerhead turtle nesting activity on Hutchinson Island. Considerable decreases in,ocean temperatures, par-ticularly between late July and mid-August 1986 (Figure 10), may have been due to such cool water intrusions. Though several short-term decli; nes i'n nesting may have been related to sharp decreases in water tem-perature during 1986, the observed decline in nesting from late July through mid-August 1986 is consistent with normal temporal nesting pat-terns on Hutchinson Island and is not necessarily attributable to the decline in water temperature during that period.

To determine if plant operation affected seasonal nesting patterns (nest density on a month-to-month basis), the nesting patterns for Area 4 26

(plant site) and Area 5 (control site) during each study year were com-pared statistically (Kolmogorov-Smirnov test; Sokal and Rohlf, 1981).

There was no significant (P<0.05) difference in temporal nesting patterns between Areas 4 and 5 during any study year, either before or during power plant operation. The results of these analyses indicated that plant operation has not significantly affected temporal nesting patterns.

Predation on Turtle Nests Since nest surveys began in 1971, raccoon predation probably has been the major cause of turtle nest destruction on Hutchinson Island.

Researchers at other locations have reported raccoon predation levels as high as 70 to nearly 100 percent (Davis and Whiting, 1977; Ehrhart, 1979; Hopkins et. al., 1979; Talbert et al., 1980). Raccoon predation of loggerhead turtle nests on Hutchinson Island has not approached this level during any study year, though levels for individual 1.25-km-long areas have been as high as 80 percent (Table 5). Overall predation rates I

for survey years 1971 through 1977 were between 21 an'd 44 percent, with the high of 44 percent recorded in 1973. A pronounced decrease in rac-coon predation occurred after 1977, and overall predation rates for the nine areas have not exceeded 10 percent since 1979 (Figure 12).

Decreased pr edation rates may have been the result of various fac-tors. Decreased predation in Areas 3 and 4 after 1977 may have been par-tially due to trapping programs that resulted in the removal of a number of raccoons from these areas during 1979 and 1980. Also, construction activities associated with installation of intake and discharge struc-27

tures may have deterred raccoons from Area 4 during 1981, 1982 and 1983.

Increased predation in Area 4 during 1985 and 1986 may reflect an increase in the raccoon population in this area. Decreased predation in Areas 8 and 9 probably reflects a decline in the raccoon population which may be due to habitat destruction associated with development of adjacent upland habitat in these areas (Williams-Walls et al., 1983). However, a substantial increase in predation in Area 9 during the last two years suggests that the raccoon population in that area is recovering from pre-vious declines. Diseases also may be responsible for reductions in rac-coon populations. Apparently, raccoon populations in Florida's coastal

~

+

areas are occasionally decimated by canine distemper (Ehrhart, 1979).

This might explain substantial reductions in predation in Areas 1 and 2 which have not undergone development. ~ I ~

Overall predation rates for the entire island have varied from two to eight percent since whole island surveys began in 1981. During 1986, five percent (283) of the loggerhead nests (n=5,483) on the island were 4

depredated by raccoons. Results of whole island surveys'ndicate that predation of turtle nests by raccoons was primarily restricted to the most undeveloped portion of the island (i.e., Areas E through U) and the southernmost areas (Areas II and JJ; ABI, 1982, 1983, 1984b, 1985b, 1986; Figure 13). During 1985 and 1986, predation rates in Areas II and JJ were substantially higher than during the previous four years and pro-bably reflect an increase in the raccoon population on the southern end of the island.

28

' v a ' t '

> ~

Ghost crabs have been reported by numerous researchers as important predators on sea turtle nests (Baldwin and Lofton, 1959; Schulz, 1975; Diamond, 1976; Fowl er, 1979; Hopkins et al ., 1979; Stancyk, 1982).

Though turtle nests on Hutchinson Island may have been depredated by ghost crabs since nesting surveys began in 1971, this source of predation did not become" apparent as a cause of nest destruction until 1983.

guantification of ghost crab predation was initiated in that year.

Overall predation rates by ghost crabs have varied from 0.5 to 2.1 per-cent during the last four years. During 1986, 1.0 percent (53) of the loggerhead nests (n=5,483) on the island were destroyed by ghost crabs (Figure 13). Nests destroyed by a combination of raccoon and ghost crab predation have been included as raccoon predations in previous t

discussions. When these combination predations are included as crab pre-dations, the overall predation rates by ghost crabs range from 2.2 to 3.2 percent. During 1986, 3.2 percent (176 nests) were destroyed by either ghost crabs or a combination of ghost crabs and raccoons.

Green and Leatherback Turtle Nestin Green and leatherback turtles also nest on Hutchinson Island, but in fewer numbers than loggerhead turtles. Prior to 1981, both survey (nine

. 1.25-km-long sections) and inter-survey areas were monitored for the pre-sence of green and leatherback nests. Thirty-one kilometers of beach from Area 1 south to the St. Lucie inlet were included in that effort.

During whole island surveys from 1981 through 1986, only one of 83 leatherback nests and only three of 278 green nests were recorded on the five kilometers of beach north of Area 1. Therefore, previous counts of 29

green and leatherback nests within the 31 kilometers surveyed were pro-bably not appreciably different from total densities for the entire island. Based on this assumption, green and leatherback nest densities may be compared among all survey years, except 1980, when less than 15 kilometers of beach were surveyed.

Prior to 1986, the number of nests observed on the island ranged from 5 to 68 for green turtles and from 1 to 20 for leatherbacks (Figure 14). During the 1986 survey, 45 green turtle and 7 leatherback turtle nests were recorded on Hutchinson Island.

Temporal nesting patterns for these species differ from the pattern for l oggerhead turtl es. Green turtl es typical ly nest on Hutchinson Isl and from mid-June through the first or second week. of September.

During 1986, green turtles nested from 25 Nay through 7 September.

Leatherback turtles usually nest on the island from mid-April through early to mid-July. During 1986 this species nested from 3 tray through 15 June.

Considerable fluctuations in green turtle nesting on the island have occurred among survey years (Figure 14). This is not unusual since there are drastic year-to-year fluctuations in the numbers of green turtles nesting at other breeding grounds (Carr et al., 1982). Despite these fluctuations, green turtle nesting has remained relatively high during the last five years (1982 through 1986) and may reflect an increase in the number of nesting females in the Hutchinson Island area. During 30

1986, green turtles nested most frequently along the southern half of the island (Figure 15). This is consistent with results of previous surveys (ABI, 1983, 1984b, 1985b, 1986; Mi lliams-Mails et al., 1983).

Leatherback turtle nest densities have remained low on Hutchinson Island; however, densities during the last seven survey years have been higher than during the first four survey years. This may reflect an overall increase in the number of nesting females in the Hutchinson Island area. During 1986, leatherback turtles primarily nested on the southern half of the island between Areas U and FF.

Intake Canal Honitorin Entrainment of sea turtles at the St. Lucie Plant has been attri- C ~

I'l buted to the presumed physical attractiveness of the offshore structures housing the intake pipes rather than to plant operating characteristics (ABI, 1980b and 1986). Even when both units are operating at full capa-city, turtles must actively swim into one of the intake pipes before they encounter current velocities sufficiently strong to effect entrainment.

Thus, canal capture rates relate primarily to the probability of arly one of the intake structures being detected by a turtle. This probability varies proportionately to the number of turtles occurring in the vicinity of the sturctures. Assuming that detection distances do not vary appre-ciably over time and that all turtles (or a constant proportion) are equally attracted to the structures, temporal fluctuations in canal cap-tures should reflect natural variability in the structure of the popula-tion being sampled.

31

S ecies Number and Temporal Distribution During 1986, 220 sea turtle captures, including 208 individual ani-mals, took place in the intake canal of the St. Lucie Plant (Table 6).

All five species of sea. turtles occurring in coastal waters of the southeastern United States were represented in the catches, including 183 loggerheads, 22 greens, 1 leatherback, 1 hawksbill and 1 Kemp's ridley.

Since intake canal monitoring began in tlay 1976, 1,322 loggerhead (including 71 recaptures), 192 green (including 1 recapture), 8 leather-back, 4 hawksbill and 4 Kemp's ridley captures have been reported from the St. Lucie Plant.

t 1976 Annual catches (Figure 16).

of loggerheads increased steadily from (partial year of plant operation After declining loggerheads. again rose between steadily, reaching a'nd 1979 and 1981, a

a low of 33 monitoring) to 173 in 1979 yearly catches of high of 195 during 1986.

in The mean annual catch of loggerheads during years of full plant operation was 128.9 ( 41.4).

Two offshore intake structures were in place prior to Unit 1 start-up in 1976; the third and largest structure was installed du< ing 1982-1983. Even though all three structures are in relatively close proximity, the addition of the third structure may have expanded the overall field of detection and thus increased the probability of a turtle being entrained. Because this change cannot be quantified, data collected prior to 1982 may not be comparable with that collected after 1983. Nevertheless, the continued rise in canal captures since 1981, 32

~ ~

even after the third structure was completed, suggests a genuine, long-term increase in the number of turtles occurring near the plant.

When data from all years of monitoring are combined, the majority of loggerhead captures occurred in January (12.6 percent); fewest captures occurred during May, November and December (Table 7). However, monthly catches have shown considerable annual variability. Months having rela-tively low catches one year often have had relatively high catches in another. During 1986, the monthly catch of loggerheads ranged from 8 (November) to 34 (June), with a monthly mean of 16.3 (a7.7). Over the entire monitoring period, monthly catches have ranged from 0 to 39; the greatest number of captures occurred during January 1983.

Catches of green turtles also have varied highly among years, ranging from 0 in 1976 (partial year of sampling) to 69 in 1984 (Table 8). The average annual, catch of green turtles, excluding 1976, was 19.2

(+19.8). No consistent trends in annual catches are evident from the data (Figure 16).

Green turtles have been caught during every month of the year, with average monthly catches for all years combined ranging from 0.2 in May to 7.4 in January. However, seasonal abundance patterns of greens are much more pronounced than for loggerheads, . 64.6 percent of all captures occurring during the first three months of the year. During 1986, the largest number of greens (6) were captured in March. The most greens ever caught in one month was 37 in January 1984.

33

0 Catches of leatherbacks, hawksbills and Kemp's ridleys have been infrequent and scattered throughout the eleven year study period (Table 6). Each species has occurred with greatest frequency during abbreviated portions of the year; all but one of the eight leatherbacks were collected between February and May, three of the four hawksbills were collected in July and August, and all of the Kemp's ridleys were caught between January and March.

Size-Class Distributions To date, live loggerheads removed from the intake canal have ranged in length (SLCL) from 41.5 to 112.0 cm (R = 64.9 ~ 11.9 cm) and in weight from 10.9 kg to 154.7 kg (Figures 17 and 18). A carapace length of 70 cm approximates the smallest size of nesting loggerhead females observed along the Atlantic east coast (Hirth, 1980). However, adults can only be reliably sexed on external morphological characteristics (e.g., relative tail length) after obtaining a length of about 80 cm. Based on these divisions, data were segregated into three groups: juvenile/sub-adults

(<70 cm; the demarcation between these two components is not well established in the literature), adults (>80 cm) and transitional (70-80 cm). The latter group probably includes some mature and some immature individuals. Of the 1,185 captures for which length data were collected, 75 percent were juveniles/sub-adults, the majority of these measuring between 50 and 70 cm SLCL (Table 9). The remaining 25 percent was divided equally between adults and individuals in the transitional size class. Similar size-frequency distributions, indicating a preponderance of juveniles, have been reported for the Mosquito/Indian River Lagoon

McYea, 1982), Georgia and South Carolina (Hillestad et al., 1982) and suggest that coastal waters of the southeastern United States constitute an important developmental habitat for Caretta caretta.

Seasonal patterns of abundance for various size classes indicated that juveniles and sub-adult loggerheads were slightly more abundant during the winter than at other times of the year (Table 9). About 38 percent of juvenile/sub-adult loggerheads were captured between January and March, the remainder being rather evenly distributed among other months. The seasonal distribution of adult loggerheads was much more pronounced, 58 percent of all captures occurring between June and August.

This represents the period of peak nesting dn Hutchinson Island. If other nesting months are included (Hay and September), 74 percent of all adults were. captured during the nesting season.

Green turtles removed alive from the intake canal over the entire study period ranged in size from 20 to 108 cm SLCL (x = 36.9 x 15.1 cm) and 0.9 kg to 177.8 kg (Figures 20 and 21). Nearly all (96 percent) were juveniles or sub-adults and most (74 percent) were less than 40 cm in length. These immature turtles exhibited distinct winter pulses suggesting migratory behavior. However, some immature gr een turtles were present throughout the year. To date, only five adult green turtles (SLCL >88 cm; Ehrhart, 1980) have been removed from the canal; all were captured during or shortly after the nesting season.

35

Three of the four hawksbills and all four Kemp's ridleys removed from the canal were immature, ranging in size from 34 to 46 cm SLCL (6.4-12.7 kg) and 27 to 47 cm SLCL (3.2-15.4 kg), respectively; the adult hawksbill (SLCL >53 cm; Hi rth, 1980) had a SLCL of 70 cm and weighed 52.2 kg. By contrast, at least six of the eight leatherbacks were adults (SLCL >121 cm; Hi rth, 1980) ranging in length from 112.5 to 150 cm. The largest leatherback for which an accurate weight was obtained weighed 233.6 kg and was a male with a SLCL of 134.5 cm.

Sex Ratios Since intake canal monitoring began in 1976, 161 individual logger-heads have been sexed by external morphological or behavioral charac-on Hutchinson Island subsequent to her capture in the canal. Females predominated males by a ratio of 4.37:1.00, which significaltly departs from a 1:1 ratio 2 (X , P<0.05). Consequently, temporal patterns in the number of adult loggerhead captures are heavily influenced by the numbers of females present. When sexes were separated, it was evident that males were relatively evenly distributed among different months, whereas nearly 80 percent of the females were taken during the nesting season (May through September; Figure 19).

The number of adul t loggerheads captured at the St. Lucie Pl ant increased dramatically after 1982. Between 1976 and 1982, an average of seven adult loggerheads were entrapped each year, whereas over- the last four years, an average of 28 adults per year were captured. This 36

increase corresponds to a general rise in loggerhead nesting on Hutchinson Island. The year 1986 represented the highest number of nests ever recorded for the island, and more adults (40) were entrapped in the canal than ever before. This association is not unexpected, since the majority of adults captured were females and most of these were entrained during the nesting season. Increased nearshore movement associated with nesting behavior increases the probability of the intake structures being detected and hence the probability of entrainment. The addition of the third offshore intake structure, the largest of the three structures, in 1982 also may have contributed to increased entrainment of adults.

Since September 1982, 224 juvenile and sub-adult loggerhead turtles captured in the canal have been sexed by Texas A 8 N University researchers using a bioimmunoassay technique for blood serum testosterone. For the purpose of these analyses, Dr. Owens and his asso-ciates used 76 cm as the cutoff length between immature and adult turtles; Bioimmunoassay results indicate that for immature loggerheads

. removed from the St. Lucie Plant intake canal, females outnumbered males by a ratio of 2.67: 1.00. The sex ratios of immature loggerheads captured in the Cape Canaveral ship channel (1.72:1.00) and the Indian River Lagoon (1.40:1.00) are also reported to be significantly skewed in favor of females (X, P<0.05; Wibbels et al., 1984).

Of the five adult green turtles captured since monitoring began, four were males and one was a female. Six immature green turtles have been sexed through blood work; all have been females. Of the five adult 37

I cather back turtl es for which sex was recorded, two were femal es and three were males. The only hawksbill thus far sexed was a female. No sex information exists for Kemp's ridleys.

Ca ture Efficiencies Capture methodologies evolved over the first several years of intake canal monitoring as net materials, configurations and placement were varied in an effort to minimize sea turtle entrapment times.

Concurrently, alternative captur e techniques were evaluated and potential deterrent systems tested in the laboratory. Ouring this period, capture efficiencies varied in relation to fishing effort and the effectiveness {

\

of the systems -deployed.

t Between October 1980 and January 1981 a capture/recapture study was 4~ ~

conducted to determine turtle net capture. efficiency based on length of.

entrapment between successive captures {ABI, 1983). Eleven loggerheads

(( ~

were captured and released back into the canal. Recapture intervals ranged from less than a day to 38 days, with an average recapture inter-

/

val of 10.3 days. Seventy-five percent of all recaptures occurred within 14 days of previous capture. Although the sample size was relatively small, these data suggested that for turtles confined between the A1A barrier net and intake headwalls, entrapment times were relatively short.

This has been supported by more recent formal daily inspections of the canal between the A1A barrier net and the intake headwalls. Turtles entering the canal have generally been captured within one to two weeks of the time they were first observed, and many have been caught the following day.

38

A turtle's entrapment period in the canal may be extended if it swims through, over or under the barrier net at the A1A bridge. Over the years, the net has been ci rcumvented when water levels in the canal were ~ '1 exceptionally high (primarily when flow rates for both units were low) or the bottom of the net pulled free from the substrate (primarily when a large amount of debris accumulated in the net). Because fishing efforts for turtles in the canal west of the barrier net generally have been less C+ ~

effective than those between A1A and the headwalls, the majority of indi-viduals breaching the barrier net usually are not removed from the canal

~ l until they enter -the intake wells of Units 1 and 2.

I r.

1 Over the entire monitoring period, 15.4 percent of turtle captures I

(all species combined) in the, canal system have occurred at the intake

'ells. Because of their small size, many green turtles are able to swim I

through the. large mesh of the barrier'et; 51.6 percent of all green cap- h 'i.

tures have occurred at the intake wells.- Similarly, two of the four hawksbi'mls have been removed from the canal at the intake wells. By contrast, only 10.1 percent of the loggerheads entrapped in the canal have circumvented the barrier net later to be caught in the intake wells.

All leatherbacks and three of the four Kemp's ridleys have been captured in turtle nets set between the A1A bridge and the headwalls.

g ~

C 'I To maximize confinement of larger turtles to the easternmost section of the intake canal, and thereby increase overall capture efficiency, the AlA barrier

~

net has been periodically surveyed and, as required, appropriate .'easur es taken to ensure its integrity. During 39

drag caused by fouling assemblages and the surface c'able to which the float line is attached was raised and tightened to reduce overwash-These measures corresponded with a moderate decline in intake well cap-tures during 1986. Between 1976 and 1985, the percentage of loggerheads and green turtles removed from the canal at the intake wells was 10.6 and 53.5 percent, respectively. During 1986, these percentages declined to 7.2 percent for loggerheads and 36.4 percent for greens.

Relative Condition Turtles captured alive in the intake canal of the St. Lucie Plant were assigned a relative condition based on weight, activity, parasite infestation, barnacle coverage, wounds and injuries and any other abnor-malities which might have affected overall well-being (Table 10). During

~ ~ ~

1986, 76.9 percent (150) of all loggerheads found in the canal were alive and in good to excellent condition. Only 9.2 percent (18) of loggerhead captures involved individuals in fair or poor condition; 13.8 percent (27) of the loggerheads removed from the canal were dead. Of the 22 green turtles removed from the intake canal during 1986, 86.4 percent (19) were in good to excellent condition, 9.1 percent (2) were in fair or poor condition and 4.5 percent (1) were dead. The only hawksbill cap-tured during 1986 was in excellent condition, while the leatherback and Kemp's ridley were in good condition.

Over the entire monitoring period, 67.1 and 77.6 percent, respec-tively, of all loggerhead and green captures have involved turtles in 40

good to excellent condition (Table 10). Captures of individuals in fair to poor condition have occurred 24.2 percent of the time for loggerheads and 12.5 percent of the time for greens. With the exception of one leatherback in fair condition and one Kemp's ridley in poor condition, all other species captured in the intake canal have been in good to excellent condition.

Relative condition ratings can be influenced by a number of factors, some related and others unrelated to entrainment and/or entrapment in the intake canal. Ratings of good to excellent indicate that turtles have not been negatively impacted by their 'entrapment in the canal, at least as evidenced by physical appearance. Although ratings of fair or poor

, ~ imply reduced responsible vitality, the extent to which entrainment/entrapment is often indetermi nable. In some instances, conditions is responsible. for lower ratings, such as injuries, obviously were sustained prior to entrainment. However, in other cases, pre-entrainment con-ditions are less easily recognized.

It appears that once in the canal, an individual's relative con-dition is related to the length of time it remains entrapped. As indi-cated ear lier, entrapment periods are relatively short for turtles remaining between the A1A barrier net and intake headwalls, while resi-dency times increase for those individuals breaching the barrier net.

Since 1976, 134 loggerheads, 99 greens, two hawksbills and one Kemp's ridley have been removed from the intake wells of Units 1 and 2. When

relative condition of loggerheads captured in turtle nets is compared 41

with that of individuals removed from the intake wells, the effect of extended residence in the canal system becomes apparent. For loggerheads caught in the turtle nets, 71.7 percent were in good to excellent con-dition and 20.7 percent were in fair or poor condition (Table 11). By comparison, only 26.1 percent of the loggerheads removed from the intake wells were in good to excellent condition, whereas 56.0 percent were in fair (39.6 percent) or poor (16.4 percent) condition. Many of thos'e in the latter two categories were noticeably underweight and lethargic.

Differences in relative condition between turtles captured by turtle nets and those removed from the intake wells was much less pronounced for green turtles than for loggerheads. About 80 percent of green turtles caught by nets and 76 percent of those removed from the intake wel'ls were in good to excellent condition (Table 11). Although the percentage of greens removed from the intake wells in fair or poor condition was twice that for greens captured by net, the total number of individuals rated as fair or poor was relatively small, constituting only 12.5 percent of the total catch.

Differences in relative condition between loggerheads and greens removed from the intake wells may relate to differences in size and/or behavioral characteristics between the two species. Many greens removed from the canal are small enough to swim through the mesh of the barrier nets. Because of their size, their movements are more likely to be influenced by currents, thus accelerating their arrival times at the intake wells. By comparison loggerheads breaching the barrier net have

,42

been observed to orient against the currents, and because of their larger size, their movements in the canal are less influenced by flow patterns.

Consequently, loggerheads breaching the barrier net probably spend a greater period of time in the canal relative to their Chelonia counter-parts. These findings prompted adjustments to the A1A barrier net during 1985 in an effort to reduce the number of 1'oggerhead breaches.

Several loggerheads removed from the intake wells have had a black discoloration of the plastron and carapace indicating that they may have been buried in the mud at the bottom of the canal. This phenomenon has been observed for loggerheads in other areas of Florida and is thought to be an overwintering mechanism (Carr et al., 1980-1981). Hibernation by loggerheads in the canal would certainly extend an individuals's period of entrapment which could in turn affect its relative condition.

The relative condition assigned to a turtle is a subjective assess-ment prone to some variation among observers and fs based solely on phy-sical appearance. A turtle's physical appearance may or may not relate to its physiological health. Thus, measures of physiological condition are desirable. One such measure involves blood chemistry.

Blood hemoglobin levels have been measured in turtles removed from the intake canal since September 1982. Measurements for 330 loggerheads and three greens ranged from 5.0-14.6 g/100 ml and 4.0-10.5 g/100 ml, respectively. ~ Mean values increased from 7.7 g/100 ml for loggerheads in poor condition to 10.0 ~ g/100 ml for those in excellent condition (Figure

hemoglobin levels. However, there was a great deal of overlap in ranges between groups. Frair (1977) reported that many factors, such as tem-perature, sex, size and activity, can affect an individual turtle's blood chemistry irrespective of general health. Thus, hemoglobin data taken collectively from the entire population over different seasons and environmental conditions probably masks differences which might otherwise be attributable to differences in health among individuals within distinct segments of the population. As the data base continues to grow, hemoglobin values can be partitioned by size classes, sex and season to hopefully reduce vapiability and thus produce a better gauge of relative health within each sub-group.

Mortalities During 1986, 27 (13.8 percent) of the 195 loggerheads removed from the canal were dead. This was the largest number of mortalities and the second highest rate (proportion of total catch) recorded since monitoring began. Two of the dead loggerheads were removed from the intake wells, one drowned in the turtle net and the remainder were found tangled in or floating against the A1A barrier net. There were no apparent external injuries to any, but because of the advanced stage of decomposition, cause of death for most could not be determined. One .green turtle was found dead in the intake canal during 1986; it was removed from the intake wells.

Over the entire eleven year monitoring period, 105 (7.9 percent) of the 1,322 lo'ggerheads and 16 (8.3 percent) of the 192 green turtles removed from the canal were dead (Table 6). Mortalities spanned the range of size classes for loggerheads (SLCL = 47. 5-125 cm), while all green turtle mortalities involved juveniles less than 41 cm in length.

No leatherback, hawksbill or Kemp's ridley mortalities have occurred at the St. Lucie Plant.

Canal mortalities have been closely monitored throughout the life of the monitoring program in an attempt to assign probable causes and take appropriate corrective actions to reduce future occurrences. A thorough analysis of the data collected from turtles captured between 1976 and 1985 identified drowning in nets, drowning in the intake pipes during periods of reduced intake flow, injuries sustained from dredging opera-tions and injuries sustained from the mechanical rakes used in the intake wells as probable mortality factors (ABI, 1986).

To date, 12 of the 105 loggerhead intake canal mortalities apparently resulted from drowning after entanglement in nets (7 in turtle nets, 3 in barrier nets and 2 in gill nets used for fish sampling; Table 12). Because of their small size, a larger percentage of green turtle mortalities (50.0 percent) resulted from drownings, all the result of entanglement in the turtle nets. To reduce mortalities of this nature, nets have been modified (e.g., lead lines removed) and deployment tech-niques altered (e.g., increased scope on securing lines) over the years to allow turtles easier movement after entanglement. Even with this pre-45

~ ~ k

caution, a loggerhead drowned in the turtle net during 1986. It was entang1 ed wi th two other individual s which apparently rest ri cted its movement and ability to surface. The last such incident for a loggerhead was June 1980. The last green turtle to drown in a turtle net was in November 1983.

The deaths of seven loggerheads during a 15 day period in 1982 pro-bably resulted from dredging activities in the canal. All were found during and shortly after dredging of a basin for a new intake headwall.

Four of these 'turtles had external injuries obviously resulting from con-

-tact with the bucket used to excavate bottom sediments. The others had no visible injuries. No dredging has occurred i n the intake canal since 1982, and measures will be taken to minimize injuries to turtles during future construction.

Another possible cause of canal mortalities has been attributed to the operating capacity of the plant. During periods when both units (or Unit 1 prior to Unit 2 operation) are operating at low capacity, current velocities within the intake pipes may be insufficient to ensure a rapid transport of turtles from the intake structures into the intake canal.

Turtles within the pipes for relatively long periods may drown if they become confused and are unable to reach either terminus to surface. To evaluate the effect of reduced intake flow on canal mortalities, periods t

of low flow were identified and compared with unexplained mortalities east of the A1A barrier net. Low flow was arbitrarily established as a total combined flow for Units 1 and 2 of less than 3.8 X 10 -m .day

~ l 0

-1 (100 MGD). During periods of full operation, each unit discharges condensor cooling water at the rate of about 2.8 X 10 .m .day" (738 HGD).

Unit 2 was placed on line in Hay 1983 and, since September of that year, no low flow days have occurred. Prior to September 1983, 39 unexplained mortalities occurred in the canal east of the A1A barrier net. 'eventy-five percent of these were found within 10 days of low flow conditions. This percentage is grossly disproportionate to the percen-tage of days during which low flow conditions existed (15 percent).

Three of the low flow mortalities were confirmed by necropsy to have

~

resulted from drowning as evidenced by water in the lungs. The exact cause of death for the remainder could not be determined because of their advanced stage of decomposition, but the lack of apparent external injuries also suggests drowning. Although attempts to correlate deaths with specific operating conditions are complicated by the lack of infor-mation regarding intervals between time of death and time of recovery, the association between low volume cooling water intake and canal mor-talities seems strong. Now that both units are fully operational and scheduled outages can be staggered, few low flow days are expected.

Low flow conditions cannot be advanced to explain any of the mor-talities recorded since September 1983 nor about 25 percent of the loggerhead mortalities which occurred east of the A1A bridge prior to that date. During the three year period from 1983 through 1985, there were a total of only 11 loggerhead mortalities, representing just 2.6 47

percent of the total catch. Seven of these were unexplained and occurred east of the barrier net. However, in 1986, a dramatic increase in mor-talities was observed, 23 unexplained deaths occurring in the eastern portion of the canal over a ten month period. The only identifiable change in plant operating conditions or canal characteristics between 1985 and 1986 was the adjustment to the barrier net made during the late summer of 1985 (see Capture Efficiencies).

Except for the one loggerhead which drowned in the turtle net, all of the loggerhead mortalities east of the A1A bridge during 1986 were discovered tangled in or floating against the barrier net. Most were in stages of decomposition when first encountered, even though 'dvanced I

daily inspections of the net were made after mortality incidents became .

persistent. Three turtles wer e removed shortly after death, but resusci-tation efforts were unsuccessful. Drowning was suggested by froth around the mouth when these turtles were inverted. The lack of apparent exter-nal injuries suggests drowning to be the probable cause of death for the other turtles as well.

The changes in barrier net characteristics (or other canal features) during 1986 which might have increased the probability of a turtle drowning could not be positively identified. Assuming that the turtles were not dying elsewhere and then being carried by currents into the net, steps were taken to remedy the drowning problem by cutting large holes in the net. This measure, which was implemented in October, was intended to provide escape hatches to turtles which might otherwise be pinned against 48

the net by currents. Yet, the net continued to provide some degree of deterrence to turtles attempting to leave the eastern part of the canal.

The success of this interim corrective. measure cannot be evaluated fully until more time has elapsed, but no additional mortalities occurred

• ~

I during November and. December 1986. A new barrier net, designed to mini-I mize the potential for drowning, is scheduled to be installed at the AlA bridge during 1987.

Injury sustained during passage through the intake pipes does not appear to result in turtle mortalities. Although several sea turtles l

removed from the intake canal 'during 1986 had recent lacerations and/or abrasions, the majority of these injuries were of a superficial nature and appeared to be of little consequence to the turtle's well being-i Only five loggerheads with substantial injuries (deep cuts, broken or m'i ssing appendages, etc. ) were captured.. Four were mi ssing appendages; however, these wounds were well-healed, indicating that they had been sustained prior to entrapment in the canal. The fifth loggerhead had debilitating injuries which appeared to have resulted from contact wi th a boat prop. If so, this injury probably occurred prior to entrainment.

A portion of the unexplained canal mortalities may result when turtles are entrained when already in poor health and later succumb to natural mortality. Based on entra P ment times and relative condition most turtles confined between the A1A barrier net and intake headwall are probably removed before heal th-rel ated mortal ities occur. However, extended periods in the canal and deteriorating health might be a mor-49

0 ality factor for turtles breaching the A1A barrier net. Over the eleven year monitoring period, five loggerheads were found floating dead in the canal west of the barrier net and an additional 17 loggerhead and four green carcasses have been removed from the intake wells (Table 12).

Cause of death for two greens and two loggerheads removed from the wells could be attributed to injuries sustained from the mechanical rakes used to remove debris from the wells. The other two green turtles had numerous fibropapilomas (tumors) which may have compromised their health.

Cause of death for the remaining loggerheads was undetermined. It has already been suggested that relative condition of loggerheads depreciated for individuals breaching the A1A barrier net and this was believed related to an individual's extended period of entrapment. Changes in nvironment and lack of natural food items may further lead to mor-talities, particularly for those individuals which initially entered the canal system in poor health.

Reca ture Incidents Since the St. Lucie Plant capture program began, most turtles removed alive fr om the intake canal have been tagged and released back into the ocean at various locations along Hutchinson Island.

Consequently, individual turtles can be identified as long as they retain their tags. Over the eleven year history of turtle entrapment at the St.

Lucie Plant, 41 individuals (40 loggerheads and 1 green) have been removed from the canal more than once. Several other turtles with tag scars have also been removed, indicating that the actual number -of recap-ures may be higher.

50

Of the 40 individual loggerheads known to have been caught more than once, 26 were caught twice, six were caught three times, four were caught four times, three were captured six 'times and one was caught on seven P

separate occasions, yielding a total of 71 recapture incidents. Release site did not appear to have any effect on a turtle's probability of being recaptured. Turtles released both north and south of the plant retur ned.

Recaptures also did not appear to be related to size, as both juveniles and adults were captured more than once (range of SLCL = 47-89 cm).

However, as with their overall relative abundance in the canal, the majority of recapture incidents (81 percent)'nvolved juveniles and sub-adults (SLCL <70cm). A

'" ~ I ~

I g

Recapture intervals for loggerheads ranged from four to 858 days, I Is 1

7 gl with a mean of 137.3'days (s157.7 days). The only green turtle caught

'I, more than once was captured on two occasions, returning to the canal 59

~ ,e'.'

days after first being released into the ocean. Nearly 63 percent of all II loggerhead recapture incidents occurred within 90 days of previous cap- l ture and 94 percent within one year (Figure 22). The average interval between first and last capture was 249.2 days (+251.1 days). These data suggest that residency times of most loggerheads, particularly juveniles/sub-adults, within the nearshore habitat adjacent to the St.

Lucie Plant are relatively short. Similar findings have been reported for loggerheads inhabiting the Mosquito/Indian River Lagoons of east-central Florida (Mendonca and Ehrhart, 1982).

51

SUMMARY

A gradient of increasing loggerhead turtle nest densities from north to south along Hutchinson'sland has been shown during all survey years.

This gradient may result from variations in beach topography, offshore depth contours, distribution of nearshore reefs, onshore artificial lighting and human activity on the beach at night. Low nesting activity in the vicinity of the power plant during 1975 and from 1981 through 1983 was attributed to construction of power plant intake and discharge systems. Nesting returned to normal or above normal levels following both periods of construction. Power plant operation, exclusive of intake/discharge construction, has had no significant effect on nest den-sities.

There have been considerable year-to-year fluctuations in loggerhead nesting activity on Hutchinson Island from 1971 through 1986.

Fluctuations are common at other rookeries and may result from overlapping of non-annual breeding populations. The greatest nesting activity ever recorded on the island, including a record 5,483 loggerhead

~ nests, occurred during 1986. No relationship between total nesting and power plant operation or intake/discharge construction was indicated.

Results of three years of tagging studies on Hutchinson Island indi-cated that an average of two nests per year were produced by each nesting loggerhead turtle. Based on this average, the nesting population of loggerhead turtles on the island has varied from approximately 1,400 e individuals in 1977 to over 2,700 in 1986. The temporal nesting pattern

~ ~

0 of this popul ation may be influenced by fluctuations in water tem-perature. Though natural temperature fluctuations have apparently affected temporal nesting patterns on Hutchinson Island, no significant effect due to power plant operation was indicated.

Since nest surveys began in 1971, raccoon predation was considered the major cause of turtle nest destruction on Hutchinson Island. From 1971 through 1977, overall predation rates in the nine survey areas were between 21 and 44 percent. However, a pronounced decrease in raccoon predation occurred after 1977, and overall predation rates in the nine survey areas have not exceeded ten percent since 1979. Decreased preda-During 1986, 45 green turtle and 7 leatherback turtle nests were recorded on. Hutchinson Island. Green turtle nesting activity exhibited considerable annual fluctuations, as has been recorded at other rookeries, but has remained relatively high during the last five years.

Annual leatherback nest densities during the last seven survey years were higher than during any of the previous four survey years.

During 1986, 195 loggerheads, 22 green turtles, 1 leatherback, 1 hawksbill and 1 Kemp's ridley were removed from the canal. Since intake canal monitoring began in May 1976, 1,322 loggerhead, 192 green, 8 t ridley turtles leatherback, 4 hawksbill and 4 Kemp's have been captured.

Over the life of the monitoring program, annual catches for loggerhead turtles have ranged from 33 in 1976 (partial year of plant operation and 53

monitoring) to a high of 195 in 1986. Yearly catches of green turtles

'ave ranged from 0 in 1976 to 69 in 1984. Differences in the number of turtles entrapped during different years and months were attributed to

~

natural variation in the occurrence of turtles in the vicinity of the offshore intake structures, rather than to any influence of the plant itsel f.

Size-class distributions of loggerhead turtles removed each year from the canal have consistently been predominated by juveniles and sub-adults between 50 and 70 cm in straight line carapace length. Most green turtles'ntrapped in the canal (74 percent) were juveniles less than 40 cm in length. For both species, the largest number of captures for all years combined occurred during the first three months of the year, but these winter peaks were much more pronounced for green turtles. Sex

~

ratios of both adult and immature loggerheads caught in the canal con-tinued to be biased towards females.

During 1986, about 77 percent of all loggerheads and 86 percent of all green turtles removed from the canal were categorized by physical appearance as being in good to excellent condition. Over the entire ele-ven year monitoring period, 67 and 77 percent, respectively, of all loggerhead and green turtle captures have involved individuals in these categories; 24 percent of the loggerheads and 13 percent of the green turtles removed from the canal have been in fair or poor condition.

Because most turtles confined between the AlA barrier net and the intake headwalls were captured within a relatively short period of time, their physical condition did not appear to be affected by entrapment.

Thus, turtles removed from this area of the canal in fair or poor con-dition probably entered the canal in the same physical state. However, about 10 percent of all loggerheads and 52 percent of all green turtles entering the canal system circumvented the barrier net and were not removed from the canal until they entered the intake, wells of Units 1 and

2. The relative condition of loggerheads breaching the AlA barrier net appeared to be negatively affected as a result of extended periods of entrapment. However, the relative condition of green turtles removed from the intake wells did .not differ appreciably from those caught by turtle nets.

Ouring. 1986, one green and 27 loggerhead mortalities were recorded for the intake canal. This dramatic increase from previous years was attributed to adjustments made to the AlA barrier net late in 1985. The adjustment is presumed to have somehow increased the probability of a turtle drowning in the net. Interim corrective measures .to the barrier net were undertaken concurrently with the evaluation of alternative net designs.

Since intake canal monitoring began in 1976, 7.9 percent of the loggerheads and 8.3 percent of the green turtles removed from the canal were dead. All of the leatherback, hawksbill and Kemp's ridley turtles have been captured alive and released back into the ocean. Although 55

exact causes of death could not be determined for most turtle mor-talities, *a variety of probable causes, including drowning in nets, drowning in the intake pipes during periods of low flow, poor health and minedd, activities exa-injuries from mechanical rakes and dredging have been and where possible, corrective actions taken to prevent future occurrences.

56

(

I LITERATURE CITED ABI (Applied Biology, Inc.) 1977. 'Ecological monitoring at the Florida Power & Light Co. St. Lucie Plant, annual report 1976. Volumes I and II. AB-44. Prepared by Applied Biology, Inc, for Florida Power

& Light Co., Miami.

1978. Ecological monitoring at the Florida Power L~g t o. St. Lucie Plant, annual report 1977. Volumes I and II. AB-101. Prepared by Applied Biology, Inc. for Florida.

Power & Light Co., Miami.

1979. Florida Power & Light Company., St.

uc1e ant annua non-radiological environmental monitoring report 1978. Volumes II and III, Biotic monitoring. AB-177. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami .

C 1980a. Florida Power & Light Company, St.

Lucie P ant annual non-radiological environmental monitoring report 1979. Volumes I I and I II, Biotic monitoring. AB-244. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

1980b. Turtle entrainment deterrent study.

- 9 . repare y plied Biology, Inc. for Florida Power & Light Co., Miami.

1981a. Successful relocation of sea turtle nests near the St. Lucie Plant, Hutchinson Island,Miami Florida. AB-317.

Prepared by Applied Biology, Inc. for Florida Power & Light Co.,

Mi ami.

1981b. Florida Power & Light Company, St.

Luci e P ant annua non-r adiological environment monitoring report 1980. Volumes II a'nd III, Biotic monitoring. AB-324. Prepared by Applied Biology, Inc. Florida Power & Light Co., .

198lc. Proposed St. Lucie plant preopera-iona an opera rona biological monitoring program -August 1981.

AB-358. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

1982. Florida Power & Light Company, St.

Lucre P ant annua non-radiological environmental monitoring report 1981. Volumes II and III, Biotic monitoring. AB-379. Prepared by Applied Biology, Inc. for Florida'PoHer & Light Co., Miami.

1983. Florida Power & Light Company, St.

uc>e ant annua non-radiological aquatic monitoring report 1982.

Volumes I and II. AB-442. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

57

LITERATURE CITED (continued)

ABI (Applied Biology, Inc.). 1984a. Florida Power & Light Company, St.

Lucie Plant annual non-radiological environmental monitoring'report 1983. Volumes I and II. AB-530. Prepared by Applied Biology, Inc.

for Florida Power & Light Co., Miami.

1984b. Florida Power & Light Company, St.

Lucie Plant annua environmental operating report 1983. AB-533.

Prepared by Applied Biology, Inc. for Florida Power & Light Co.,

Ni ami.

1985a.'lorida Power & Light Company, St.

ucse ant annua non-radiological environmental monitoring report 1984. AB-553. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

1985b. Florida Power & Light Company, St.

Lucre P ant annua environmental operating report 1984. AB-555.

Prepared by Applied Biology, Inc. for Florida Power & Light Co.,

Juno Beach.

1986. Florida Power & Light Company, St.

Lucre ant annua env ronmental operating report 1985. AB-563.

0 P.

Prepared by Applied Biology, Inc. for Florida Power & Light Co.,

Juno Beach.

Baldwin, W.P., Jr. and J.P. Lofton, Jr. -1959. The loggerhead turtles of Cape Romain, South Carolina. Previously unpublished manuscr ipt abridged and annotated by D.K. Caldwell, without the authors.

In D.K. Caldwell and A. Carr, coordinators, The Atlantic loggerhead sea turtle, Caretta caretta caretta (L.), in America. Bulletin of the Florida St~ac Fluseum, eelo~og>ca Sciences, 4(10):319-348.

Bellmund, S., N.T. Hasnik and G. LaRoche. 1982. Assessment of the impacts of the St. Lucie 2 Nuclear Station on threatened or endangered species. U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation.

Bustard, H.R. 1968. Protection for a rookery: Bundaberg sea turtles.

Wildlife in Australia 5:43-44.

Bustard, H.R. and P. Greenham. 1968. Physical and chemi cal factors affecting hatching in the green sea turtle, Chelonia mydas (L.).

Ecol ogy 49(2):269-276.

Caldwell, D.K. 1962. Comments on the nesting behavior of Atlantic loggerhead sea turtles, based primarily on tagging returns.

quarterly Journal of the Florida Academy of Sciences 25(4):

287-302.

58

LITERATURE CITED (continued)

Caldwell, D.K., A. Carr and L.H. Ogren. 1959. Nesting and migration of the Atlantic loggerhead turtle. in D.K. Caldwell and A. Carr, coor-dinators, The Atlantic loggerhead sea turtle Caretta caretta caretta (L.), in America. Bulletin of the florida state museum, BIo~ogvca Sci ences, 4(10):295-308.

Camp, D.K., N.W. Whiting and R.E. Martin. 1977. Nearshore marine eco-1 ogy at Hutchinson Isl and, Fl orida: 1971-1974. V. Arthropods.

Florida Marine Research Publications 25, 1-63.

Carr, A., A. Meyl an, J. Mortimer, K. Bjorndal and T. Carr. 1982.

Surveys of sea turtl e popul ati ons and habi tats in the Western Atlantic. NOAA Technical Memorandum NMFS-SEFC-91:1-82.

Carr, A., L. Ogren and C. McVea. 1980-1981. Apparent hibernation by the Atlantic loggerhead turtle Caretta caretta off Cape Canaveral, florida. Biological Conservatvon lg:7-14. Il,l Davis, G.E., and M.C. Whiting. 1977. Loggerhead sea turtle nesting in Everglades National Park, Florida, U.S.A. Herpetologica 33:18<<28.

Di amond, A.W. 1976.~ Breedi ng bi ol ogy and conservat i on of Hawksbi 1 1 turtles, Eretmochelys imbricata L., ~ on Cousin Island, Seychelles.

AASS I'L.I lmll-c5.

~ ~

I

~

r Ehrhart, L.M. 1979.~ Reproductive characteristics and management poten-tial of the sea turtle rookery at Canaveral National Seashore, Florida. Pages 397-399 in Linn, R.M., ed. Proceedings of the First 1",

Conference on Scientifsc Research in the National Parks, 9-12 5~

November, 1976, New Orleans, La. NPS Trans. and Proc. Ser. No. 5..

55<<55555555 1980. Threatened and endangered species studies for environmentally monitoring space transportation systems of the Kennedy (STS) at John F. Kennedy Space Center. Contract No. NAS 10-8986.

Vol. IV NASA Report. 163122. September 1980.

Ernest, R.G., R.E. Martin, B.D. Peery, D.G. Strom, J.R. Wilcox and N.W.

Walls. In Press. Sea turtle entrapment at a coastal power plant.

Proceedings of Southeastern Workshop on Aquatic Ecological Effects of Power Generation, 3-5 December, 1986, Sarasota, Flor'ida.

Fowler, L.E. 1979. Hatching success and nest predation in the green sea turtle, Chelonia mydas at Tortuguero, Costa Rica. Ecology 60(5):945n)55. l ~

Frair, W. )977. Turtl e red blood cel 1 packed volumes, sizes, and numbers. Herpetol ogi ca 33:167-190.

0 59

LITERATURE CITED (continued)

Futch, C.R. and S.E. Dwi nel 1. 1977. Nea rsho re ma rine ecol ogy at Hutchinson Island, Florida: 1971-1974. IV. Lancelets and Fishes.

Florida Marine Research Publications 24, 1-23.

Gallagher, R.M. 1977. Nearshore marine ecology at Hutchinson Island, Fl orida: 1971-1974. I I. Sediments. Fl orida Marine Research Publications 23, 6-24.

Gallagher, R.M. and M.L. Hollinger. 1977. Nearshore marine ecology at Hutchinson Isl and, Fl orida: '971-1974. I. Introduction and rationale. Florida Marine Research Publications 23, 1-5.

Gal lagher, R.M., M.L. Hollinger, R.M. Ingle and C.R. Futch. 1972.

Marine turtl e nesting on Hutchinson Isl and, Fl orida in 1971.

Florida Department of Natural'esources, Special Scientific Report 37:1-11.

Hendrickson, J.R. and E. Balasingam. 1966. Nesting beach preferences of Malayan sea turtles. Bulletin of the National Museum Singapore 33(10):69-76.

Hillestad, H.O., J. I. Richardson,

~ ~ ~ C.~ McVea, Jr. and J.M.~ Watson, Jr.

1982. Worldwide incidental capture of sea turtles. Pages 489-496 in Bjorndal, K.A., ~ ~ ed.~ Biology and conservation of sea turtles.

Smithsonian Institution Press, Washington,~ D.C.~

Hi rth, H.F. 1980. Some aspects of'the nesting behavior and reproductive biology of sea turtles.. American Zoologist 20:507-523.

Hopkins,'.R., T.M. Murphy, Jr., K.B. Stansell and P.M. Wilkinson. 1979.

Biotic and abiotic factors affecting nest mortality in the Atlantic loggerhead turtle. Proceedings Annual Conference of Southeastern Fish and Wildlife Agencies 32:213-223.

Hughes, G.R. 1974. The sea turtles of southeast Africa, 1. Status, distributions.

morphology and South African Association for Marine Biological Research, Oceanogr aphic Research Institute, Investigational Report No. 35:1-144.

1976. Irregular reproductive cycles in the Tongaland

, c Cc.) Cc c c .'cc c Zoologi ca Africana ll(2~8%791.

Mendonca, M.T. and L.M. Ehrhart. 1982. Activity, population size and structure of the immature Chelonia mydas and Caretta caretta in Mosquito Lagoon, Florida. Copepia 19 !2: lll1-167.

60

~ ' ~

Moffler, M.D. and J.F. Van Breedveld. 1979. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. X. Benthic algae species list. Florida Marine Research Publications 34, 118-122.

Mortimer, J.A. 1982. Factors influencing beach selection by nesting sea turtles. Pages 45-51 in Bjorndal, K.A., ed. Biology and conserva-tion of sea turtles. Smithsonian Institution Press. Washington, D.C.

NMFS (National Marine Fisheries Service). 1978. Final EIS listing and protecting the green sea turtle (Chelonia mydas), loggerhead sea turtle (Caretta caretta) and tile pac>ficCBdley sea turtle (Lepidochelyys o iv~acea D.C.

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under the Endangered Species Act of 1973.

hI NRC (U.S. Nuclear Regulatory Commission) statement rel ated to the operation

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Final environmental Luci e Plant Unit 2.

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O'ara, J. 1980. Thermal influences on the swimming speed of loggerhead turtl e hatchl ings. Copei a 1980(4):773-780.

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in North American waters.

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1982. Apparent hibernation'y sea turtles Pages 127-132 in Bjorndal, K.A., ed.

Biology and conservation of sea turtles. Smithsonian Institution Owens, D.W., J.R. Hendrickson, V. Lance and I.P. Gal lard. 1978.

for determining sex of immature Chelonia mydas using a A'echnique radi oimmunoassay. Herpetol ogi ca 34:270-273.

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126 pp.

Proffitt, C.E., R.E. Martin, R.G. Ernest, B.J. Graunke, S.E. LeCroy, K.A. Muldoon, B.D. Peery, J.R. Wilcox and N. Williams-Walls. 1986.

Effects of power plant construction and operation on the nesting of the loggerhead sea turtle (Caretta caretta):1971-1984. Copei a 1986(3): 813-8)6.

e 61 u ' e

LITERATURE CITED (continued)

Raymond, P.W. 1984. The effects of beach restoration on marine turtles nesting in south Brevard County, Florida. N.S. thesis, University of Central Florida.

Routa, R.A. 1968. Sea turtle nest sur vey of Hutchinson Island, Florida.

quarterly Journal Florida Academy of Sciences 30(4):287-294.

Schul z, J.P. 1975. Sea turtl es nesting in Surinam. Zool ogi sche Verhandeli ngen, uitgegeven door het Rijksmuseum van Natuurlijke Historic te Leiden, No. 143:1-144.

Smith, N.P. 1982. Upwelling in Atlantic shelf waters of south Florida.

Florida Scientist 45(2):125-138.

Sokal, R.R. and F.J. Rohlf. 1981. Biometry. The principles and prac-tice of statistics in biological resear'ch. . W.H. Freeman and Company, San Francisco. 859 pp.

Stancyk, S.E. 1982. Non-human predators of sea turtles and their con-trol. Pages 139-152 in Bjorndal, K.A., ed. Biology and conserva-tion of sea turtles. Smithsonian Institution Press. Washington, D.C.

e Tal bert, O.R., S.E. Stancyk, J.M. Dean and J.H. Mill. 1980.

activity of the loggerhead turtle (Caretta caretta) in South Carolina. I: A rookery in transition. Copeia 1980:709-718.

taurine Nesting Taylor, C.B., and H.B. Stewart. 1958. Summer upwelling along the east coast of Florida. Journal of Geophysical Research 64(l):33-40.

Tester, L.A. and K.A. Steidinger. 1979. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. VI I. Phytopl ankton, 1971-1973. Florida Research Publications 34, 16-61.

Walker, L.H. 1979. Nearsho re ma ri ne ecol ogy at Hutchi nson Isl and, Fl orida: 1971-1974. IX. Di el pl ankton, 1973-1974. Fl orida Harine Research Publicati one 34,99-117.

Walker, L.H., B.H. Gl ass and B.S. Roberts. 1979. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. VIII.

Zooplankton, 1971-1973. Florida Marine Research Publications 34, 62-98.

Walker, L.N. and K.A. Steidinger. 1979. Nearshore marine ecology at Hutchinson- Isl and, Florida: 1971-1974. VI. Plankton dynamics, 1971-1973. Florida Marine Research Publications 34, 1-15.

0 62

LITERATURE CITED (continued)

Wibbels, T., D. Owens, Y. Morris and M. Amoss. 1984. Sex ratios of immature loggerhead sea turtles captured along the Atlantic coast of the United States. Final Report to the National Marine Fisheries Service. Contract No. NA81-GA-C-0039. 47 pp.

Williams-Walls, N., J. O'ara, R.M. Gallagher, D.F. Worth, B.D. Peery and J.R. Wi 1 cox. 1983. Spati al and temporal trends of sea turtl e nesting on Hutchinson Isl and, Fl orida, 1971-1979. Bul 1 etin of Marine Sci ence 33(1):55-66.

Worth, D.F. and M.L. Hol linger. 1977. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. III. Physical'nd chemical environment. Florida Marine Research Publications 23, 25-85.

Worth, D.F., and J.B. Smith. 1976. Marine turtle nesting on Hutchinson Island, Florida, in 1973. Florida Maririe Research Publications No; 18:1-17.

63

1 GULF OF MEXICO t YAADS NLO4CTCllS

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St, Lude Plant

~ z Figure 1. Location of the St. Lucie Plant.

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INTAKE STRUCTURES INTAKE BARRIER

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0 250 500 METERS Figure 2. St. Lucie Plant cooling water intake and discharge system.

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1-km segments surveyed for sea turtle nesting, Hutchinson Island, 1971-1986. ~

30 971 1973 1975 200 100 300 1977 1979 1980 200 uj 100 0

K 1981 1982 1983 g 300 D

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'2 100 1 2 3 4 5 6 7 8 9 12 3 4 5 6 7 8 9 3 4 5 6 7 8 9 NORTH A PLANT SITE SOUTH NORTH A PLANT SITE SOUTH NOR. M ~ PLANT SITE SOUTH Figure 4. Number of loggerhead turtle nests in each of the nine 1.25-km-long survey areas, Hutchinson Island, 1971-1986. (Only Areas 3 through 6 were surveyed during 1980.)

45 971 1973 1975 300 False crawls not recorded 150 450 1977 1979 1980

~U 300 49150 1981 1982 1983

~ 450

~ 300 Z

150 450 1984 1985 1986 300 150 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 NORTH A PLANT SITE SOUTH NORTH A PLANT SITE SOUTH NORTH A PLANT SITE SOUTH

'h 1

Figure 5. Number of emergences by loggerhead turtles in each of the nine 1.25-km-long survey areas, Hutchinson Island, 1973-1986. (Only Areas 3 through 6 were surveyed during 1980.)

1971 1973 1975 40 False crawIs not recorded 20 1977 1979 1980 60 g

M 2 CO O

U 1981 1982 1983 M

(g 60 z

co 40 z

20 1984 1985 1986 60 40 20 12 3 4 5 6 7 8 9 12 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 NORTH A PLANT SITE SOUTH NORTH A PLANT SITE SOUTH NORTH A PLANT SITE SOUTH Figure 6. Loggerhead turtles nesting success (percentage of emergences that resulted in nests) for each of the .

nine 1.25-km-long survey areas, Hutchinson Island, 1973-1986. (Only Areas 3 through 6 were .surveyed in 1980.)

1981 1982 20 150 100 4

I, fc

'50 250 1983 1984

~200

~

z u 150 0

uj 100 X

g. 50 1985 1986 250 200 150 100 k

50 ABCDEFG HI JKLMNO P Q R S T U VWXYZABCDEFG A ABC 0 E FG Hl J HI J w

ABCD EFG Hl J KL'MNOPQRSTU VWXYZABC DE FGH A ABCDEFGHI J I J NORTH PLANT SITE SOUTH NORTH PLANT SITE SOUTH Figure 7. Number of loggerhead turtle nests in each of the thirty-six 1-km-long survey areas, Hutchinson Island, 1981-1986.

1981 1982 300 200 100

.pXq O

400 1983 1984 g

300 200 0

100 5pp 1985 1986 400 300 200 100 ABCDEFGHI JKLMNOPQRSTUVWXYZABCDEFGHIJ ABCDEFGHI JKLMNOPQRSTUVWXYZABCDEFGHIJ A ABCDEFGHI J A ABCDEFGHI J NORTH PLANT SITE SOUTH NORTH PLANT SITE SOUTH Figure 8. Nuqber of emergences by loggerhead turtles in each of the thirty-six 1-km-long survey areas, Ilutchinson Island, 1981-1986.

1981 1982 80 4 60 5

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t$

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1 g 1983 1984 80.

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20-L ABCDE FGHI JKLMNOPQRSTUVWXYZABCDEFGHIJ ABCDEFGH IJK LMNOPQRSTUVWXYZABCDEFGHIJ A ABCDEFGHIJ A ABCDEFGHI J NORTH PLANT SITE SOUTH NORTH PLANT SITE SOUTH Figure 9. Loggerhead turtle nesting success (percentage of emergences that resulted in nests-) for each of the thirty-six l-km-long survey areas, Hutchinson Island, 198l-1986.

30 28 26 24 I-22 120 V) g 90 60 30 15 30 5 15 30 5 15 30 5 15 30 5 15 30 5 15 APR MAY JUN JUL AUG SEP Figure 10. Daily loggerhead turtle nesting activity and water temperature, Hutchinson Island, 1986.

1971 19?3 1975 30 15 45 19?7 1979 1981 30 15 0

45 1982 1983 1984 G.

30 15 45 '985 '. 1986 30 15

~ -.I APR MAY JUN JUL AUG SEP APR MAY JUN, JUL AUG SEP APR MAY JUN JUL AUG SEP Figure 11. Percentage of the total number of loggerhead turtle nests ovserved in the nine 1.25-km-long survey areas during each month, 1971-1986, Hutchinson Island.

ALLAREAS 50 AREA 1 50 AREA 2 50 AREA 3 50 0-0K AREA 4 O

o) 50 I-Z AREA 5 50 R

AREA 6 50 AREA 7 50 AREA 8 50 AREA 9 50 1971 1973 1975 1977 1979 1980 1981 1982 1983 19841985 1986 Figure 12. Percentage of loggerhead nests destroyed by raccoons in the nine 1.25-km-long survey areas, Hutchinson Island, 1971-1986.

100 O Destroyed by ghost crabs H Destroyed by raccoons and ghost crabs L~J Destroyed by raccoons O 49m 80 V) 60 31 z

0 K

40 Z

15%

20 4% 31, 1'%el% 1% 2/e A 8 C D E F G H I J K L MN 0 PQ R S T U VW X Y Z A B CD E F G H I J l ABCDEFGHI J NORTH PLANT SITE SOUTH Figure 13. Number of loggerhead turtle nests destroyed by raccoons and ghost crabs and destroyed nests as a percentage of the total number of nests for each 1-km-long survey area, Hutchinson Island, 1986.

~ o---o 8 8 Green Turtle Nests Leetherbpck Turtle Nests Ii 60 /

I /

I /

I s /

h 45

/ h I

I I

m I 30 I Z I I

I I

15 I 1971 1973 1975 1977 1979 1981 1982 1983 1984 1985 1986 Figure 14. Number of green turtle and leatherback turtle nests, Hutchinson Island, 1971-1986.

15 10 Z

0 K

uj 5

D Z

ABC DEFG Hl J KLMNOPQRSTUVWXYZABCDE FG HI J ABCDEFGHI J NORTH PLANT SITE SOUTH Figure 15. Number of green turtle nests in each 1-km-long survey area, Hutchinson Island, 1986.

~

O- --0 G LOGGERHEAD (Caretta GREEN (Chelccla m~das) caratta) 80 200 175 70 I) 150 60 5

/

O 125 I 50

/

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0 100 / 40 I

I 75 I 30 mm

/ /

0 20 Z

50

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/ 10 25

-0 Or 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 Figure 16. Number of loggerhead and green turtles removed each year from the intake canal, St. Lucie Plant, 1976-1986.

300 300 V) 200 200 O

z0 0

K 6) 100 100 z

c40 41-45 46-50 51-55 56-60 61-65 66-70 71-75 76-80 81-85 86.90 91-95 96- 101- 106- 111- 116-100 105 110 115 120 STRAIGHT LINE CARAPACE LENGTH (cm)

/

Figure 17. Length distribution (SLCL) of live loggerhead sea turtles (N=1,122) removed for the first time from the intake canal, St. Lucie Plant, 1976-1986.

180 180 160 160 140 140 D

D 120 120 O

z 100 100 K

m 80 80 D

2'.

60 60 40 40 20 20 20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 H 101- 151- 201- 251- 301- <<350 150 200 250 300 350 WElGHT (Ibs)

Figure 18. Weight distribution of live loggerhead sea turtles (N=984) removed for the first time from the intake canal, St. Lucie Plant, 1976-1986.

MALES 30 0 FEMALES 30 M

20 20 O

D 2'

K lU Gl 10 10 z

A xkc JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH OF CAPTURE Figure 19. Numbers of adult loggerheads (N=164), including recaptures, removed each month from the intake canal, St. Lucie Plant, 1976-1986.

0 60 50 50 CO 0

40 40 O

Z 30 30 IQ X

D 20 -20 10 10

~1 5 16- 21- 26- 31- 36 46- 51- 56 66- 71 81- 86- 91- 96- 101- 106- 111 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 STRAIGHT LINE CARAPACE LENGTH (cm)

Figure 20. Length distribution (SLCL) of live green turtles (N=174) removed for the first time from the intake canal, St. Lucie Plant, 1976-1986.

0 80 -80 M

D D

60 -60 D

z

'0 K

uj 40 40 D

z 20 20

<10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81.90 91-100 101- 151- 201- 251 - ~300 150 200 250 300 WEIGHT (Ibs)

Figure 21. I<eight distribution of live green sea turtles (H=170) removed for the first time from the intake canal, St. Lucie Plant, 1976-1986.

o. 0<<

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>r

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9 Interval between successive captures P

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0 I

I O

P 20 100 200 300 400 500 600 700 800 SOO 1000 RECAPTURE INTERVAL(days)

Figure 22. Cumulative percentage of all loggerhead recaptures occurring within various time intervals between successive captures and first and last capture, St. Lucie Plant intake canal, 1976-1986.

(103)

(83) 14 (56)

(86) 10 E

C)

O CO z

8 0

C9 0

POOR FAIR GOOD VERY EXCELLENT GOOD RELATIVE CONDITION Figure 23. Hemoglobin values for loggerhead turtles of different relative conditions taken from the intake canal, St. Lucie Plant, September 1982 - December 1986. Horizontal lines are means, boxes enclose one standard deviation and vertical lines are ranges. Numbers of individuals used in analyses are shown in parentheses.

E 1 NUMBER OF LOGGERHEAD TURTLE NESTS IN EACH OF THE 1.25-KH-LONG SURVEY AREAS HUTCHINSON ISLAND 1971 - 1986 Preo erational 0 erational Area 1971 1973 -

1975 1977 1979 1980 1981 1982 1983 1984 1985 1986 110 96 48 47 66 98 80 120 71 112 92 132 108 55 80 101 139 107, 154 134 127 3 113 156 90 93 109 83 140 112 130 140 208 4b 152 134 73 100 123 133 67 91 110 144 184 261 171 126 158 106 144 104 169 186 133 174 187 218 141 250 109 233 175 139 278 199 177 220 220 136 127 155 76 204 126 84 202 150 213 225 238 164 281 161 237 181 265 302 177 256 . 235 215 182 216 187 288 164 270 294 254 231 264 TOTAL 1420 1260 1493 932 1449 528 1031 1634 1592 1439 1623 1839 I

a Only Areas 3-6 were surveyed during 1980.

b St. Lucie Plant Site.

NUMBER OF EHERGENCES BY LOGGERHEAD TURTLES IN EACH OF THE 1.25-Kfl-LONG SURVEY AREAS HUTCHINSON ISLAND 1973-1986a Preo erational 0 erational Area 1973 1975 1977 1979 1980 1981 1982 1983 1984 1985 1986

.164. 161 102 126 165 143 176 137 180 173 182 79 149 182 220 180 253 297 323 210 301 138 176 220 177 203 218 222 310 363 4c 172 139 187 292 159 161 227 271 406 242'50 168 288 212 271 229 292 346 259 347 433 227 433 224 438 401 309 410 399 337 495 391 200 283 164 377 239 283 349 258 327 369 230 420 333 459 324 375 494 289 422 383 9 259 354 333 476 314 434 471 403 392 389 TOTAL 1803 2561 1747 2769 1184 - 2059 2543 2827 2468 3133 3290 a

False crawls (non-nesting emergences) were not recorded during 1971.

b Only Areas 3-6 were surveyed during 1980.

St. Lucie Plant Site.

'e LOGGERHEAD TURTLE NESTING SUCCESS IN EACH OF THE 1.25-KH-LONG SURVEY AREAS HUTCHINSON ISLAND 1973  ; 1986b 0 erational Area 1973 1975 1977 1979 1980 1981 1982 1983 1984 1985 1986 1 67 60 62 46 59 56 68 52 62 76 59 70 54 56 63 59 61 39 69 52 65 53 50 69 51 59 45 57 4d 78 53 54 51 42 49 53 57 I 5 75 55 50 41 45 58 54 51 50 43 CO 6 62 49 53 68 50 53 56 7 55 46 54 53 65 58 58 65'1 61 y ~

71 67 48 52 56 71 61 61 I

70 61 56 61 52 62 62 63 59 68 Mean 70.2 57.8 55. 6 51.7 49.8 63.6 55.6 58.6 51.8 56.0 Standard 5.4 4.7 8.4 5.6 5.1 5.1 4.8 5.5 8.0 9.3 deviation Nesting success is the percentage of emergences that result in nests.

b False crawls (non-nesting emergences) were not recorded during 1971.

c Only Areas 3-6 were surveyed during 1980.

d St. Lucie Plant Site.

ESTIMATES OF THE NUMBERS OF LOGGERHEAD TURTLE NESTS BASED ON SURVEYS OF NINE 1.25-KH-LONG SURVEY AREAS IN 1971-1986 AND THE ACTUAL NUMBER OF NESTS FOUND 1981-1986 HUTCHINSON IS)AND Estimates of the number of nests on the entire island Actual number Linear regression orrected . of nests on the Year e uation Y=a+bx r Re ression Extra olation extra olation entire island 1971 Y = 65.87 + 4.7lx 0.73 1420 5423 4544 4217 1973 Y ~ 108.34 + 1.62x 0.60 1260 4950 4032 3742 1975 Y = 61.31 + 5.36x 0.61 1493 5680 4778 4434

,1977 Y = 29.26 + 3.81x 0.74 932 3522 2982 2768 1979 Y = 7.53 + 7.87x 0.96 1449 537-1 4637 4304 1981 Y = 44.24 t 3.6lx 0.82 1031 3932 3299 3062 3115 1982 Y = 62.35 + 6.1lx 0.74 1634 6204 5229 4853 4690 1983 Y = 27.35 + 7.67x 0.93 1592 5955 5094 4728 4743 1984 Y = 63.21 + 4.60x 0.70 1439 5256 4605 4274 4277 1985 Y = 80.21 + 5.13x 0.84 1623 6218 5194 4820 4877 1986 Y = 128.38 + 3.90x 0.55 1839 7149 5885 5462 5483 a

Y = The number of nests; a = The Y intercept; b = The slope of the regression line; x = The distance (km) south of Ft. Pierce Inlet.

~ ~ = ~ ~ S, a W ~ +i= r ~- a i ~~ - < S V- - v

NUt<BER AND PERCENTAGE OF LOGGERHEAD TURTLE NESTS DESTROYED BY RACCOONS IN EACH OF THE NINE 1.25-KH-LONG SURVEY AREAS HUTCH INSON ISLAND 1971-1986 Preo erational 0 erational 1971 1973 1975 1977 1979 1980a Area Number Percent Number Percent Number Percent Number Percent Number Percent Number Percent 28 33 79 72 40 42 36 75 2 30 33 71 54 27 25 18 33 3 66 58 115 80 101 65 63 70 10 4b 32 21 33 9 12 47 44(

60 35 69 55 16 10 25 33 35 32 30 14 13 9 0 0 0 0 0 0 0 0 5 4 2 2 1 1 13 17 10 5 63 26 66 40 24 9 <1 37 90 49 92 43 146 78 49 17 TOTAL 393 28 310 21 351 38 126 50 10 Only Areas 3-6 were surveyed during 4980.

b St. Lucie Plant Site..

TABL (continued) .

NUMBER AND PERCENTAGE OF LOGGERHEAD TURTLE NESTS DESTROYED BY RACCOONS IN EACH OF THE NINE 1.25-KH-LONG SURVEY AREAS HUTCHINSON ISLAND 1971-1986 0 erational 1981 1982 1983 1984 1985 1986 Area Number Percent Number Percent Number Percent Number Percent Number Percent Number Percent 1 9 14 0 0 1 1 17 14 8 11 1 1 2 14 14 3 12 ll 20 13 13 10 30 24 3 7 8 2 24 21 7, 5 1 <1 4b 2 3 1 6 5 39 21 27 10 5 9 9 47 28 47 25 18 10 25 13 1 0 0 1 1 0 0 0 0 0 0 0 0 0 1 <1 0 0 0 0 0 0 0 0 0 0 1 <1 0 0 0 0 0 9 10 25 9 12 60 26 101 38 TOTAL 52 54 3 118 7 66 145 185 10 a

Only Areas 3-6 perh surveyed during 1980.

b St. Lucie Plant Site.

TABLE 6 TOTAL NUMBER OF SEA TURTLE CAPTURES ANO (NUMBER OF DEAO)

TURTLES REMOVED FROM THE INTAKE CANAL

. ST. LUG IE PLANT 1976 - 1986 Annual S ecies 1976 ~

1977 1978 1979 1980 1981 1982 1983'984 1985 1986 Total Meana loggerhead 33(4) 80(5) 138(19) 173(13) 116(5) 62(5) 101(16) 119(4) 148(3) 157(4) 195(27) 1322(105) 128.9 green 5(2) 6(1) 3(1) 10(3) 32(2) 8 23(4)= 69(2) 14 22(1) 192(16) 19.2 leatherback 1 3 2'. 1 1 8(0) 0 8 hawksbill 1 "

4(0) ~

0.4 Kemp's ridley 4(0) 0.4 Total 33(4) 86(7) 148(20) 176(14) .126(8) 97(7) 110(16) 142(8) 220(5) 172(4) 220(28) 1530(121) 153.0 Excludes 1976 (partial year of plant operation).

TABLE 7 TOTAL I NfKR AND (NUHBER OF DEAD) L'OGGERHEAD TURTLES REHOVED EAGI HONTH FROH THE It(TAKE CANAL ST. LUCIE PLANT 1976 - 1986 Honthly Percent of Honth 1976 1977 197S 1979 1980 19S1 1982 19S3 1984 19S5 1986 Total Hean Total Catch 6(2), 15(2) 167(8) 16.7 12.6 3anuary February 13

-8(1) 19 11(2) 24( 3) 29(1) 16 21(2) 11(1) 11(3) '1 13(1) 13 11 11 15 16(4) 146(14) 14.6 I I.O Harch 7 27(2) 11 '14 6 6 20 14(4) 120(6) 12.0 9.1 April 5(2) 19(5) 17 0 10 14 0 2( 1) 13 20(2) 100( 10) 10.0 7.6 .

Hay 2 1 3(1) 0 7 6 I 7(4) 7 16 12 75(5) 6.8 5.7 3une 0 5 -

10 3(1) 8(3) 6 7 7(1) 28(1) 17 20('I) 111(7) 10. 1 S.4 3U I y 7(1) 4 0 27(2) 0 1 7 12(1) 20(3) 26(2) 111(9) 10. 1 8.4 August 2 3 12- 17(2) 12 6 2(1) 26 19(1) 34(6) 139( 10) 12.6 10.5 September 1 15(1) 1 8(1) 19 2(1) 9(1) 8(2) 16 14 9(4) 102( 10) 9. 3 7.7 October 7 9(1) 17(2) 15(3) 7 0 9(5) 17 10 11(2) 109( 13) 9.9 8.2 November 5( 3) 5 15(7) 12 4 0 4(2) 70(12) 6.4 5.3 December 9 5 4 10 8 3 1(1) 12 10 72(1) 6. 5 5,4 Total 33(4) 80(5) 138(19) 173(13) 116(5) 62(5) 101(16) 119(4) 148(3) 157(4). 195(27) 1322(105)

TOTAL tlNBER AND (NUHSER OF DEAD) GREEN TIJRTLES REHOVED EAI3I HONTH FROH THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1986 Honthly Percent of Honth 1976 1977 1978 1979 1980 19S'I 19S2 1983 1984 19S5 1986 Total Hean Total Catch 3anuary 2 1 0 0 20(1) 1 8(1) 37(1) 4 1 74(3) 7.4 38 '

February 2(1) 2 1 5(1) 7 0 4 10 1 I 33(2) 3.3 17.2 Hatch 0 2 0 4(1) 'I 0 3(2) 0 1 6(1) 17(4) 1.'7 8.9 April 1(1) 0 1(1) 0 1 1 0 I 2 3 10(2) I.O 5.2 Hay 0 0 1(1) 0 0 0 0 0 0 0 2( I) 0.2 1.0 3une 0 0 0 1 1(1) 0 0 1 3 0 1 7(1) 0.6 3.6 3uly 0 0 0 0 0 0 0 1 2 2 0.5 August 0 0 0 0 0 2(1) 2 0 2 1 1 8(1) 0.7 4.2 September 0 0 0 0 0 0 0 1 1 0 2 0.4 2.1 October 0 0 0 0 0 0 0 6 1 2 10 0.9 5.2 November 0 0 0 0 0 0 3 4(1) 4(1) 1 1 13(2) 1.2 6.8 December 0 0 0 0 0 1 1 0 3 1 2 0.7 4.2 Total 0 5(2) 6(1) 3(1) 10(3) 32(2) 8 23(4) 69(2) 14 22(1) 192(16)

NUMBER OF MONTHLY CAPTURES BY SIZE CLASS FOR LIVE LOGGERHEAD TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT 1976-1986a Size classes SLCL in cm Juveniles Sub-Adults Transition Adults Month 41-50 51-60 61-70 Total Percenta e 71-80 Percenta e 81-90 91-100 )100 Total Percenta e January 10 63 54 127 14. 3 21 14.2 2 0 8 5.4 February 6 59 49 . 114 12.8 ll 7.4 0 0 2 1.4 March 6 48 42 96 10.8 14 . 9. 5 3 0 3 2.0 April 5 26 34 65 7.3 13 8.8 1 0 6 4.1 Ul May 6 25 18 49 5.5 7 4.7 3 0 10 6.8 June 4 32 30 66 7.4 19 6.8 16 7 1 24 16. 3 July 4 29 27 60 6. 7 10 6.8 16 11 2 29 19.7 August 5 39 34 78 8.8 18 12. 2 19 12 1 32 21.8 September 2 37 29 68 7.6 9 6.1 6 2 14 9.5 October 7 33'1 71 8.0 15 10. 1 1 1 10 6.8 November 3 18 19 40 4.5 13 8.8 3 0 5 3.4 December 2 33 21 56 6.3 7 4.7 2 2 0 4 2.7 Total 60 442 388 890 75.1 148 12. 5 89 51 7 147 12.4 No data were collected for 32 individuals.

"'4; ' V l

' ~

TP0 RELATIVE. CONDITION OF SEA TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT 1976-1986 Relative condition

~h W X ~NX Leatherbacks Number Kem 's ridleys Number Hawksbills Number Number 197 14.9 47 24.5 1 12.5 2 50.0 247 16.1 287 21.7 30 15.6 1 25.0 1 25.0 319 20.8 403 30.5 72 37.5 6 75.0 2 50.0 1 25. 0 484 31. 6 249 18.8 18 9.4 1 12.5 268 17.5 72 5.4 6 3.1 1 25.0 79 5.2 6 105 7.9 16 8.3 121 7.9 9 0.7 3 1.6 12 0.8 TOTAL 1322 192 1530 1 Excellent - normal or above normal weight, active, very few or no barnacles or leeches, no wounds.

2 Very good - intermediate good to excellent.

3 Good - normal weight, active, light to medium coverage of barnacles and/or leeches, wounds absent, heal,ed or do not appear to debilitate the animal.

4 Fair - intermediate poor to good.

5 Poor - emaciated, slow or inactive, heavy barnacle coverage and/or leech infestation, debilitating wounds or missing appendages.

6 Dead 7 Alive but condition otherwise unknown.

COMPARISON OF RELATIVE CONDITIONS FOR'OGGERHEAD AND GREEN TURTLES CAUGHT IN THE TURTLE NETS AND THOSE REMOVED FROM THE INTAKE HELLS OF UNITS 1 AND 2 ST. LUCIE PLANT 1976-1986 Lo erheads Greens Relative condition Turtle nets  % Intake wells X Turtle nets 5 Intake wells 190 16.0 5.2 33 35.5 14 14.1 278 23.4 6.7. 14 15.1 16 16.2 384 32. 3 19 14.2 27 29.0 45 45.4 196 16. 5 53 39. 6 7.5 50 4.2 22 16.4 5.1 86 7.2 19 14.2 11. 8 5.1 0.3 3.7. ,0 3.0 Total 1188 89. 9 134 10.1 93 48.4 99 51. 6 1 Excellent - normal or above normal weight, active, very few or no barnacles or leeches, no wounds.

2 Very good - intermediate good to excellent.

3 Good - normal weight, active, light to medium coverage of barnacles and/or leeches, wounds absent, healed or do not appear to debilitate the animal.

4 Fair - intermediate poor to good.

5 Poor - emaciated, slow or inactive, heavy barnacle coverage and/or leech infestation, debili-tating wounds or missing appendages.

6 Dead 7 Alive but condition otherwise unknown.

~ ~

' 12 LOCATION AND PROBABLE CAUSES OF DEATH FOR SEA TURTLES FOUND DEAD IN THE INTAKE CANAL ST. LUCIE PLANT 1976-1986 Pro a e cause of eat

~OI Ii Dredging tlechanical k

Unknown Low fl ow Unknown hi gh fl ow Unknown No data Location Cc* Cm** Cc Cm Cc Cm Cc Cm Cc Cm Cc Cm East of barrier net:

Tangled in turtle net 7 Tangled in barrier net 3 Floating in canal at 20 3 29 headwall, turtle nets, barrier net or washed up on shore Subtotal 20 3 29 Hest of barrier net:

Tangled in gill net Floating in canal at 1 3 gill nets, near intake wells or washed up on shore Intake wells 14 2 1 Subtotal 1 17 2 1 Unknown TOTAL 16 2. 30 4 48 2 2

• Cc = Caretta caretta (loggerhead turtle)

• • Cm = Chelonia mydas (green turtle)