ML17227A398

Vol I to St Lucie 2 Annual Environ Operating Rept,1991.

ML17227A398
Person / Time
Site:	Saint Lucie
Issue date:	12/31/1991
From:	APPLIED BIOLOGY, INC.
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ML17227A396	List: ML17227A395 ML17227A398 ML17227A399
References
AB-617, NUDOCS 9204290199
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Text

APPLIED BIOLOGY, IN C. AB-617 I

FLORIDA POWER & LIGHT COMPANY ST. I.UCIE UNIT 2 ANNUAL ENVIRONMENTALOPERATING REPORT I VOLUME I 1991 t

I 2968 A NORTH DECATUR ROAO ~ ATLANTA, GEORGIA 30033 ~ 404-296-3900 t 92042'70199 920423 PDR ADOCK 05000389' PDR

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AB-617 FLORIDA POWER & LIGHT COMPANY ST. LUCIE UNIT 2 ANNUALENVIRONMENTAL OPERATING REPORT 1991 VOLUME 1 APRIL 1992 FLORIDA POWER 8, LIGHT COMPANY JUNO BEACH, FLORIDA APPLIED BIOLOGY, INC.

ATLANTA,GEORGIA

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i ENVIRONMENTALOPERATING REPORT IS II TABLE OF CONTENTS TABLE OF CONVERSION FACTORS FOR METRIC UNITS EXECUTIVE

SUMMARY

Introduction Turtle Nesting Survey Intake Canal Monitoring IV Other Related Activities IV INTRODUCTION

Background

Area Description Plant Description TURTLES Introduction Materials and Methods 10 Nesting Survey 10 Intake Canal Monitoring Studies to Evaluate and/or Mitigate Intake Entrapment 15 Results and Discussion 15 Nesting Survey 15 Distribution of Loggerhead Nests Along Hutchlnson Island 15 Estimates of Total Loggerhead Nesting on Hutchinson Island 19 Temporal Loggerhead Nesting Patterns 20 Predation on Loggerhead Turtle Nests 21 Green and Leatherback Turtle Nesting 22 Intake Canal Monitoring 24 Relative Abundance and Temporal Distribution 24 Size-Class Distributions 27 Sex Ratios 29 Capture Efficiencies . 31 Relative Condition 32 Mortalities 34 Recapture Incidents Summary 37 LITERATURE CITED 41 FIGURES 49 TABLES 71

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TABLE OF CONVERSION FACTORS FOR METRIC UNITS To convert Multi I b To obtain centigrade (degrees) ( Cx1.8) + 32 fahrenheit (degrees) centigrade (degrees) C + 273.18 kelvin (degrees) centimeters (cm) 3.937 x 10 inches centimeters (cm) 3.281 x 10 feet centimeters/second (cm/sec) 3.281 x 10 feet per second cubic centimeters (cm ) 1.0 x 10 liters grams (g) 2.205 x 10 pounds grams (g) 3.527 x 10 ounces (avoirdupois) hectares (ha) 2.471 acres kilograms (kg) 1.0 x 10 grams kilograms (kg) 2.2046 pounds kilograms (kg) 3.5274 x 10 ounces (avoirdupois) kilometers (km) 6.214 x 10 miles (statute) kilometers (km) 1.0 x 10 millimeters liters (I) 1.0 x10 cubic centimeters (cm )

liters (I) 2.642 x 10 gallons (US liquid) meters (m) 3.281 feet meters (m) 3.937 x 10 inches meters (m) 1.094 yards milligrams (mg) 1.0 x10 grams milligrams/liters (mg/I) 1.0 parts per million milliliters (ml) 1.0 x 10 . liters (US liquid) millimeters (mm) 3.937 x-10 inches millimeters (mm) 3.281 x 10 feet square centimeters (cm ) 1.550 x 10 square inches square meters (m ) 1.076 x 10 square feet square millimeters (mm ) 1.55 x 10 square inches

EXECUTlVE

SUMMARY

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

Lucie County, Florida. The plant consists of two nuclear-fueled 850-MW units; Unit 1 was placed on-line in March 1976 and Unit 2 in May 1983. This document has been prepared to satisfy the requirements contained in the United States Nuclear Regulatory Commission's Appendix B Environmental Protection Plan (EPP) to St. Lucie Unit 2 Facility Operating License No. NPF-16. This report discusses environmental protection activities related to sea turtles as required by Subsection 4.2 of the EPP. Other routine annual reporting requirements are addressed in Volume 2, also entitled "St. Lucie Unit 2 Annual Environmental Operating Report".

TURTLE NESTING SURVEY Since monitoring began in 1971, there have been considerable year-to-year fluc-tuations in sea turtle nesting activity on Hutchinson Island. However, data collected through 1991 have shown no long-term reductions in total nesting, total emergences or nesting success on the island. Relatively high nesting during recent years may ac-tually reflect an increase in the number of nesting females in the study area. On a smaller scale, power plant operation has had no significant effect on nesting near the plant.

Low nesting activity in 1975 and again in 1981 - 1983 in the vicinity of the plant was at-tributed to nighttime construction activities associated with installation of plant intake and discharge structures. Nesting returned to normal or above normal levels following

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both periods of construction. During 1991, daytime cons:truction activities associated with velocity cap repairs had no apparent effect on nesting. Formal requirements to conduct nesting surveys expired in 1986 but this program was voluntarily continued through 1991 with agreement from federal and state agencies.

INTAKE CANAL MONITORING Since plant operation began in 1976, 2,314 sea turtles (including 108 recaptures) representing five different species have been removed from the intake canal. Eighty-five percent of these were loggerheads. Differences in the numbers of turtles found during different months and years have been attributed primarily to natural variation in the occurrences of turtles in the vicinity of the plant, rather than to operational influen-ces of the plant itself. The majority of turtles removed from the intake canal (about 93 percent) were captured alive and released back into the ocean. Ongoing evaluations and improvements to the canal capture program have substantially reduced mortalities of entrapped sea turtles during recent years. Turtles confined between the A1A barrier net and intake headwalls typically reside in the canal for a relatively short period prior to capture, and most are in good to excellent condition when caught.

OTHER RELATED ACTIVITIES Studies to evaluate various intake deterrent systems, as required by the NRC's Unit 2 Environmental Protection Plan, were conducted during 1982 and 1983. Results and evaluations of those studies were presented to regulatory agencies during 1984, and the requirement is now considered completed.

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INTRODUCTION BACKGROUND This document has been prepared to satisfy the requirements contained 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 8 Light Company (FPL) was issued Permit No. CPPR-74 by the United States Atomic Energy Commission, now the Nuclear Regulatory Com-mission, that allowed construction of Unit 1 of the St. Lucie Plant, an 850-MW nuclear-powered electric generating station on Hutchinson Island in St. Lucie County, Florida.

St Lucie Plant Unit 1 was placed on-line in March 1976. In May 1977, FPL was issued Permit No. CPPR-144 by the NRC for the construction of a second 850-MW nuclear-powered unit. Unit 2 was placed on-line in May 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 for 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; Gal-lagher and Hollinger, 1977; Worth and Hollinger, 1977; Moffler and Van Breedveld,

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1979; Tester and Steidinger, 1979; Walker, 1979; Walker et al., 1979; Walker and Steidinger, 1979; Lyons, 1989). The results of Unit 1 operational and Unit 2 preopera-tional biotic monitoring at the St. Lucie Plant were presented in six annual reports (ABI, 1977, 1978, 1979, 1980a, 1981b, 1982). In January1982, a National Pollutant Discharge Elimination System (NPDES) permit was issued to FPL by the US Environmental Protec-tion Agency (EPA). The EPA guidelines for the St. Lucie site biological studies were based on the document entitled "Proposed St. Lucie Plant Preoperational and Opera-tional Biological Monitoring Program - August 1981" (ABI, 1981c). Findings from these studies were reported in three annual reports (ABI, 1983, 1984a, 1985a). The EPA biotic monitoring requirements were deleted from the NPDES permit in 1985.

Jurisdiction for sea turtle studies is with the NRC, which is considered to be the lead federal agency relative to consultation under the Endangered Species Act.

Previous results dealing exclusively with sea turtle studies are contained in eight an-nual environmental operating reports covering the period from 1983 through 1990 (ABI 1984b, 1985b, 1986, 1987, 1988, 1989, 1990, 1991). This report describes the 1991 environmental protection activities related to sea turtles, as required by Subsection 4.2 of the St. Lucie 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 1 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.

g Hutchinson Island is a barrier island that extends 36 km between inlets and ob-tains its maximum width of 2 km at the plant site. Elevations approach 5 m atop dunes bordering the beach and decrease to sea level in the mangrove swamps that are com-mon 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 at the higher elevations, and mangroves abound at the lower eleva-tions. Large stands of black mangroves, including some on the plant site, have been killed by flooding for mosquito control over past decades.

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 immediately 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 water 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-MW nuclear-fueled electric generating units that use nearshore ocean waters for the plant's once-through condenser cooling

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water system. Water for the plant 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 entrainment. 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 diameter) under the beach and dunes that lead to a 1,500-m long intake canal. This canal transports the water to the plant. After passing through the plant, the heated water is discharged into a 670-m 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, result-ing 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 diffuser). 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 sur-face of the ocean under the influence of wind and currents and the heat dissipates to

'he atmosphel'B.

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 [NRC, 1982] and in the Endangered Species Biological As-sessment (March 1982) [Bellmund et al ~, 1982] will be addressed by programs as follows:

Beach nesting surveys for all species of sea turtles will be conducted on a yearly basis for the period of 1982 through 1986. These sur-veys will be conducted during the nesting season from ap-proximately 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 purposes. Survey areas will be marked with numbered wooden pla-ques 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 obliterated 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 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.

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The study shall be implemented no later than after the final removal from the ocean of equipment and structures associated with con-struction of the third intake structure and the experiments shall ter-minate 18 months later. Four months after the conclusion of the experimental period, a report on the results of the study will be sub-mitted to NRC, EPA, National Marine Fisheries Service (NMFS), and the US 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 concurrence 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 cannot be projected to all three intake structures, then an interagency task force com-posed of NRC, EPA, NMFS, USFWS, and FPL shall convene 18 months after completion of the third intake and determine if other courses of action to mitigate and/or reduce turtle entrapment are warranted (such as physical barrier, emergence of new technology or methods to deter turtles).

4.2.3 Alternative methods or procedures for the capture of sea turtles entrapped in the intake canal will be evaluated. If a method or pro-cedure is considered feasible and cost effective and may reduce capture mortality rates, it will be field tested in the intake canal.

4.2.5 Ca ture and Release Pro ram Sea turtle removal from the intake canal will be conducted on a con-tinuing basis. The turtles will be captured with large mesh nets, or other suitable nondestructive device(s), if deemed appropriate. A formalized daily inspection, from the shoreline, of the capture device(s) will be made by a qualified individual when the device(s) are deployed. The turtles will 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/physiologi-cal data, such as blood analyses and parasite loads, from captured

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sea turtles will be pursued. Dead sea turtles will be subjected to a gross necropsy, if found in fresh condition.

INTRODUCTION Hutchinson Island, Florida, is an important rookery for the loggerhead turtle, Caret-ta ~carett and also supports some nesting of the green turtle, ~Ch ionia ~mdas and 5 9 tt ~ I .~Dh I 9 imatd Id II 1.,1959;9 t,1999;91-lagher et al., 1972; Worth and Smith, 1976; Williams-Walls et al., 1983). Allthree species are protected by state and federal statutes. The federal government classified the log-gerhead 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 5

Hutchinson Island rookery is important.

It has been a prime concern of FPL that the construction and subsequent opera-tion 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 ac-tivity 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 nest-ing surveys, nine 1.25-km-long survey areas were monitored five days per week (Figure 3). The St. Lucie Plant began operation in 1976; therefore, the first three survey years (1971, 1973 and 1975) were preoperational Though the power plant was not operat-

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ing during 1975, St. Lucie Plant Unit No. 1 ocean intake and discharge structures were

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installed during that year. Installation of these structures included nighttime construc-tion activities conducted offshore from and perpendicular to the beach. Construction had been completed and the plant was in full operation during the 1977 and 1979 sur-veys.

A modified daytime nesting sur vey 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 1991, 36 1-km-long survey areas comprising the entire island were monitored seven days a week during the nesting season (Figure 3).

The St. Lucie Plant Unit 2 discharge structure was installed during the 1981 nesting season. Offshore and beach construction of the Unit 2 intake structure 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.

During 1991, another major offshore construction project was undertaken to replace damaged velocity caps on the three intake structures. A large elevated plat-form, from which repair activities were conducted, was erected around the three struc-tures. Construction occurred throughout the nesting season. However, in contrast to

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previous offshore projects, work was restricted almost entirely to daylight hours, nighttime lighting of the work area was minimal, and no equipment or materials were used on the beach. A sea turtle protection plan implemented in support of the project included caging of nests along a 1,500 m section of beach west of the platform and release of hatchlings to unaffected areas to the north and south. This plan was intended to mitigate any negative effects potentially resulting from required safety and naviga-tional lighting on and near the platform.

Requirement 4.2.1 of the NRC's St. Lucie Unit 2 Appendix B Environmental Protec-tion Plan was completed with submission of the 1986 nesting survey data (ABI, 1987).

The nesting survey was continued voluntarily through 1991 with agreement from federal and state agencies. Results are presented in this report and discussed in relation to previous findings.

In addition to monitoring sea turtle nesting activities and relocating nests away from plant construction areas, removal of turtles from the intake canal has been an in-tegral part of the St. Lucie Plant environmental monitoring program. Turtles entering the ocean intake structures are entrained with cooling water and rapidly transported through the intake pipes into an enclosed canal system where they must be manually captured and returned to the ocean. Since the plant became operational in 1976, turtles entrapped in the intake canal have been systematically captured, measured, weighed, tagged and released.

Previous publications and technical reports have presented findings of the nest-ing surveys, nest relocation activities and canal capture program (Gallagher et al., 1972;

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Worth and Smith, 1976; ABI, 1978, 1980a, 1981 a, 1982, 1983, 1984b, 1985b, 1986, 1987, 1988, 1989, 1990, 1991; Williams-Walls et al., 1983; Proffitt et al., 1986; Ernest et al., 1988, 1989; Martin et al., 1989a, 1989b). Results of studies to assess the effects of thermal discharges on hatchling swimming speed have also been reported (ABI, 1978; O'ara, 1980). The purpose of this report is to 1) present 1991 sea turtle nesting sur-vey data and summarize observed spatial and temporal nesting patterns since 1971,

2) document and summarize predation on turtle nests since 1971, and 3) present 1991 canal capture data and summarize comparable data collected since 1976.

MATERIALSAND METHODS Nestin Surve Methodologies used during previous turtle nesting surveys on Hutchinson Island were described by Gallagher et al. (1972), Worth and Smith (1976) and ABI (1978, 1981a, 1982, 1987, 1988, 1989). Methods used during the 1991 survey were designed to allow comparisons with these previous studies.

On 10 and 12 April 1991, preliminary nest surveys were conducted along Hutchin-son Island from the Ft. Pierce Inlet south to the St. Lucie Inlet. From 15 April through 6 September, nest surveys were conducted on a daily basis. To confirm that nesting had ceased, a final survey was conducted on 9 September. Biologists used small off-road motorcycles to survey the island each morning. New nests, non-nesting emer-gences (false crawls), and nests destroyed by predators were recorded for each of the 36 1-km-long survey areas comprising the entire island (Figure 3). The nine 1.25-km-10

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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, any major changes in topography that may have affected the beach's suitability for nesting were recorded. In,addition, each of the 36 1-km-long survey areas has been 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 vertical relief) and miscellaneous characteristics (packed sand, scattered rock, vegetation on the beach, exposed roots on the primary dune, etc.).

In a cooperative effort, data from stranded turtles found during beach surveys were routinely provided to the National Marine Fisheries Service (NMFS) through the Sea Turtle Stranding and Salvage Network.

Intake Canal Monitorin Most turtles entrapped in the St. Lucie Plant intake canal were removed by means of large-mesh tangle nets fished between the intake headwalls and a barrier net located at the Highway A1 A bridge (Figure 2). Nets used during 1991 were from 30 to 40 m in length, 3 to 4 m deep and composed of 40 cm stretch mesh nylon twine. Large floats were attached to the surface, and unweighted lines used along the bottom. Turtles en-tangled in the nets generally remained at the water's surface until removed.

Since its inception in 1976, ABI's canal capture program has been under continual review and refinement in an attempt to minimize both entrapment times and in-11

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juries/mortalities to entrapped sea turtles. Prior to April 1990, turtle nets were usually deployed on Monday mornings and retrieved on Friday afternoons. During periods of deployment, the nets were inspected for captures by ABI personnel at least twice each day (mornings and afternoons). Additionally, St. Lucie Plant personnel checked the nets periodically, and ABI was notified immediately if a capture was observed. ABI's sea turtle specialists 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 the plant.

Beginning April 1990, after consultation with NMFS, net deployment was scaled back to daylight hours only. Concurrently, surveillance of the intake canal was in-creased and ABI personnel remained on site for the duration of each day's netting ac-tivities. This measure decreased response time for removal of entangled turtles from nets and provided an opportunity to improve daily assessments of turtle levels within the canal. Records of daily canal observations were compared with capture data to as-sess capture efficiencies.

The A1A barrier net is used to confine turtles to the easternmost section of the in-take canal, where capture techniques have been most effective. This net is constructed of large diameter polypropylene rope and has a mesh size of 30.5 cm x 30.5 cm. A cable and series of large floats are used to keep the top of the net above the water' surface, and the bottom is anchored by a series of heavy blocks. The net is inclined at a slope of 3:1, with the bottom positioned upstream of the surface cable. This reduces bowing in the center and minimizes the risk of a weak or injured turtle being pinned un-derwater by strong currents.

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In the past, the integrity of the barrier net was occasionally compromised, and turtles were able to move west of A1A. These turtles were further constrained downstream by an underwater intrusion detection system (UIDS) consisting, in part, of a large barrier positioned perpendicular to the north-south arm of the canal (Figure 2). The UIDS security barrier also consists of 30.5 cm x 30.5 cm mesh.

Prior to completion of the UIDS in December 1986, turtles uncontained by the A1A barrier net were usually removed from the canal at the intake wells of Units 1 and 2 (Figure 2) There they were retrieved by means of large mechanical rakes or specially

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designed nets. Following construction of the UIDS barrier, individuals with carapace widths larger than 30.5 cm were unable to reach the intake wells. Thus, as required, tangle nets were also deployed west of A1A. Improvements made to the A1A barrier net during 1990 have effectively confined all turtles larger than 30.5 cm to the eastern end of the canal.

Formal daily inspections of the intake canal were made to determine the numbers, locations and species of turtles present. Surface observations were augmented with periodic underwater inspections using SCUBA, particularly in and around the A1A bar-rier net. Because of the reduction in total netting hours since April 1990, increased ef-fort has been directed toward hand capture of turtles. This effort, accomplished by diving and use of dip nets, has proved very effective during periods of good water clarity.

Regardless of capture method, all turtles removed from the canal were identified to species, measured, weighed, tagged, and examined for overall condition (wounds, 13

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abnormalities, parasites, etc.). Healthy turtles were released into the ocean the same day of capture. Sick or injured turtles were treated and occasionally held for observa-tion prior to release. When treatment was warranted, injections of antibiotics and vitamins were administered by permitted veterinarians. 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; no necropsies were performed during 1991.

Since 1982, blood samples have been collected and analyzed 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). The samples were maintained on ice and later centrifuged for 15 minutes to separate cells and serum.

Sex determinations were subsequently made by researchers at Texas A 8 M Univer-sity using radioimmunoassay for serum testosterone (Owens et al., 1978).

Florida Power 8 Light Company and Applied Biology, Inc. continued to assist other sea turtle researchers in 1991. Since the programbegan, data, specimens and/or assistance have been given to the Florida Department of Natural Resources, National Marine Fisheries Service, US Fish and Wildlife Service, US Army Corps of Engineers, Smithsonian Institution, South Carolina Wildlife and Marine Resources Division, Center for Sea Turtle Research (University of Florida), Florida Atlantic University, University of Central Florida, Texas A 8 M University, University of Rhode Island, University of South Carolina, University of Illinois, University of Georgia, Virginia Institute of Marine Science and the Western Atlantic Turtle Symposium.

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Studies to Evaluate and or Miti ate Intake Entra ment A program that asses'sed the feasibility of using light and/or sound to deter turtles from entering the St. Lucie Plant intake structures was conducted in 1982 and 1983 and completed in January 1984. As required, test 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. Lucie Unit 2 Appendix B Environmental Protection Plan is considered completed with submission of deterrent study findings.

RESULTS AND DISCUSSION Nestin Surve Distribution of Lo erhead Nests Alon Hutchinson Island When sea turtle nesting surveys began on Hutchinson Island, nine 1.25-km-long survey areas were used to estimate loggerhead nesting activity for the entire island.

From 1971 through 1988, the distribution of nests among these nine areas indicated a gradient of increased nesting from north to south (ABI, 1989). The gradient has be-come less pronounced during the last three years and during 1991 no gradient was apparent (Figure 4). This change in the spatial distribution of nests was apparently due to a disproportionate increase in nesting in northern versus southern survey areas.

Since 1981, all 36 1-km-long segments comprising the island's coastline have been surveyed. The distribution of nests among these 36 survey areas has shown an increase in nesting from north to south only along the northern half of the island (Figure 15

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5). Along the southern half of the island there has been a gradient of decreasing nest-ing from north to south. As with the nine areas, there has been a disproportionate in-crease in nesting in northern versus southern survey areas during the last three years.

In the past, the pronounced gradient observed on the northern end of the island was occasionally influenced by physical processes occurring there; periods of heavy accretion reduced the gradient, while periods of erosion accentuated it (Worth and Smith, 1976; Williams-Walls et al., 1983). However, during recent years no consistent relationship was apparent when field observations of beach widths were compared to the spatial distribution of nests along the island (ABI, 1987). Thus, even though beach dynamics may sometimes affect the selection of nesting sites by loggerhead turtles, other factors must also contribute to the selection process. Offshore bottom contours, spatial distribution of nearshore reefs, type and extent of dune vegetation, and degree of human activity on the beach at night have been identified as some of the factors af-fecting nesting (Caldwell, 1962; Hendrickson and Balasingam, 1966; Bustard, 1968; Bustard and Greenham, 1968; Hughes, 1974; Davis and Whiting, 1977; Mortimer, 1982). Relationships between spatial nesting patterns and specific environmental con-ditions are often difficult to establish because of the interrelationship of the factors in-volved.

Not all ventures onto the beach by a female turtle culminate in successful nests.

These "false crawls" (non-nesting emergences) may occur for many reasons and are commonly encountered at other rookeries (Baldwin 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 disturban-16

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ces or unsatisfactory nesting beach characteristics. Therefore, certain factors may af-fect a turtle's preference to emerge on a beach, while other factors may affect a turtle' tendency to nest after it has emerged. An index which relates the number of nests to the number of false crawls in an area is useful in estimating the post-emergence suitability of a beach for nesting. In the present study this index is termed "nesting suc-cess" and is defined as the percentage of total emergences that result in nests.

Historically, the pattern of loggerhead emergences on the island has generally paralleled the distribution of nests (ABI, 1987, 1988), and this same trend was apparent in 1991 (Figure 6). In contrast, nesting success by loggerheads along the island has typically lacked gradients (Figure 7). Thus, the relatively high numbers of loggerhead nests observed in certain areas are usually a result of more turtles coming ashore in those areas rather than of more preferable nesting conditions being encountered by the turtles after they emerged.

Loggerhead nesting densities during 1991 were generally high when compared with previously recorded values (Figures 4 and 5). Record high nesting was recorded in 12 of the 36 one-kilometer-long survey areas and was most notable on the northern half of the island. There were no apparent changes in the physical characteristics of the beach that would account for this increase in nesting. In general, record high nest-ing was due to record high emergence rates, and this may reflect an increase in the number of nesting females in the Hutchinson Island area'.

Nesting surveys on Hutchinson Island were initiated in response to concerns that the operation of the St. Lucie Plant might negatively impact the local sea turtle rookery.

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Previous analysis, using log-likelihood tests of independence (G-test; Sokal and Rohlf, 1981) demonstrated that the construction of the plant's offshore intake and discharge structures significantly reduced nesting at the plant site during construction years 1975, 1981, 1982 and 1983 (Proffitt et al., 1986; ABI, 1987). However, nesting at the plant consistently returned to levels similar to or greater than those at a control site in years following construction (Figure 8). Power plant operation exclusive of intake/dis-charge construction has had no apparent effect on nesting.

During 1991, nesting at the power plant site remained higher than at the control site despite construction activities (velocity cap repairs) on the intake structures.

Though these construction activities proceeded throughout the summer, included the construction of a large offshore platform, and involved the use of heavy equipment, there was no apparent effect on sea turtle nesting in the vicinity of the construction.

Several aspects of the construction project minimized potential effects on nesting sea turtles. Construction activities took place almost exclusively during the day, thus mini-mizing interference with the nocturnal nesting behavior of turtles. Also, safety and navigational lighting on the platform and support vessels was designed to minimize ef-fects to sea turtles. Furthermore, no structures or materials were placed on the beach, thereby avoiding interference with the nesting behavior of emergent turtles.

Data collected through 1991 have shown no long-term reduction in loggerhead nest densities, total emergences or nesting success in either the nine 1.25-km-long survey areas or the 36 1-km-long survey areas (Table 1; Figure 9). To the contrary, data collected from both sets of survey areas indicate a long-term increase in logger-18

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Estimat s of Total L rhe Nestin n Hut hinson Island Various methods w'ere used during surveys prior to 1981 to estimate the total number of loggerhead nests on Hutchinson Island 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). Each of these methods were subsequently found to consistently overes-I timate island totals (ABI, 1987). Since whole-island surveys began in 1981, it has been possible to determine the actual proportion of total nests deposited in the nine areas.

This has then allowed extrapolation from the nine survey areas to the entire island for years prior to 1981.

From 1981 through 1991 the total number of nests in the nine areas varied from 32.5 to 35.6 percent of the total number of nests on the island (Table 1). This is slight-ly higher than the 31.3 percent which would be expected based strictly on the propor-tion of linear coastline comprised by the nine areas. Using the eleven-year mean of 33.97 percent, estimates of the total number of nests on Hutchinson Island can be cal-culated by multiplying the number of nests in the nine areas by 2.944. This technique, when applied to the nine survey areas during the eleven years in which the entire is-land was surveyed, produced whole-island estimates within 5.0 percent of the actual number of nests counted. Because the proportion of nests recorded in the nine sur-vey areas remained relatively constant over the last eleven years, this extrapolation procedure should provide a fairly accurate estimate of total loggerhead nesting for years prior to 1981 ~

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It is clear that loggerhead nesting activity on Hutchinson Island fluctuates con-siderably from year to year (Table 1). Annual variations in nest densities also are com-mon at other rookeries (Hughes, 1976; Davis and Whiting, 1977; Ehrhart, 1980) and may result from non-annual reproductive behavior (Frazer, 1989). Nonetheless, data collected through 1991 suggest an overall increase in nesting on Hutchinson Island since surveys began in 1971. Total nesting activity was greatest during 1991 when 6,812 loggerhead nests were recorded. No relationships between total nesting activity and power plant operation or intake/discharge construction were indicated by year-to-year variations in total nesting on Hutchinson Island.

Tem oral Lo erhead Nestin Patterns The loggerhead turtle nesting season usually begins between mid-April and early May, attains a maximum during June or July, and ends by late August or early Sep-tember (ABI, 1987). Nesting activity during 1991 followed this same pattern (Figure 10).

Cool water intrusions frequently occur over the continental shelf of southeast Florida 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, 1987, 1988, 1989, 1990, 1991) suggested that these intrusions may have been responsible for the temporary declines in loggerhead turtle nesting activity previously observed on Hutchinson Island. Similarly, an intrusion of cool water during late July 1991 may have contributed to the substantial decrease in nesting between late July and early August (Figure 10).

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Though natural fluctuations in temperature have been shown to affect temporal nesting patterns on Hutchinson Island, there has been no indication that power plant operation has affected these temporal patterns (ABI, 1988).

Predation n Lo erhead Turtle Nests Since nest surveys began in 1971, raccoon predation has been a 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 Whit-ing, 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. Overall predation rates for survey years 1971 through 1977 were between 21 and 44 percent, with a high of 44 percent recorded in 1973. A pronounced decrease in raccoon predation occurred after 1977, and overall predation rates for the nine areas have not exceeded 10 percent since 1979. A decline in predation rates on Hutchinson Island has been variously attributed to trapping programs, construction activities, habitat loss and disease (Williams-Walls et al., 1983; ABI, 1987) ~

During 1991, four percent (301) of the loggerhead nests (n =6,812) on the island were depredated by raccoons. As in previous years (ABI, 1991), predation of turtle nests was primarily restricted to the most undeveloped portion of the island (i.e., Areas E through S; Figure 11). However, predation rates in Areas 0 and P during 1991 were considerably lower than during previous years. This reduction is attributed to the fact that most of the nests in these two areas were covered with wire cages. These cages, 21

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originally installed to retain hatchlings during velocity cap repairs, were also effective in excluding raccoons.

Ghost crabs have been reported by numerous researchers as important predators of sea turtle nests (Baldwin and Lofton, 1959; Schulz, 1975; Diamond, 1976; Fowler, 1979; Hopkins et al., 1979; Stancyk, 1982). Though turtle nests on Hutchinson Island probably have been depredated by ghost crabs since nesting surveys began in 1971, this source of nest destruction did not become apparent until 1983. Quantification of ghost crab predation was initiated the same year.

Overall predation rates by ghost crabs have varied from 0.1 to 2.1 percent from 1983 - 1990 (ABI, 1991). During 1991, 0.5 percent (31) of the loggerhead nests (n =6,812) on the island were depredated by ghost crabs (Figure 11). Nests destroyed by a combination of raccoon and ghost crab predation have been included as raccoon predations in previous discussions. When these combination predations are included as crab predations, the overall predation rates by ghost crabs range from OA to 3.2 percent. During 1991, 1.3 percent (90 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 num-bers than loggerhead turtles. Prior to 1981, both survey (nine 1.25-km-long sections) and inter-survey areas were monitored for the presence of green and leatherback nests. Thirty-one kilometers of beach from Area 1 south to the St. Lucie Inlet were in-cluded in that effort. During whole-island surveys from 1981 through 1991, only six of 22

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226 leatherback nests and only eight of 648 green nests were recorded on the five kilometers of beach north of Area 1. Therefore, previous counts of green and leather-back nests within the 31 kilometers surveyed were probably not appreciably different from total densities for the entire island. Based on this assumption, green and leather-back nest densities may be compared among all survey years, except 1980, when less than 15 kilometers of beach were surveyed.

Prior to 1991, the number of nests observed on the island ranged from 5 to 132 for green turtles and from 1 to 36 for leatherbacks (Figure 12). During the 1991 survey, 47 green turtle and 44 leatherback turtle nests were recorded on Hutchinson Island.

Temporal nesting patterns for these species differ from the pattern for loggerhead turtles. Green turtles typically nest on Hutchinson Island from mid-June through the first or second week of September. During 1991, green turtles nested from 2 June through 1 September. Leatherback turtles usually nest on the island from mid-April through early to mid-July. During 1991 this species nested from 5 April through 18 July.

Considerable fluctuations in green turtle nesting on the island have occurred among survey years (Figure 12). 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, data collected through 1991 suggest an overall increase in nesting since 1971 and may reflect an increase in the number of nesting females in the Hutchinson Island area. During 1991, green turtles nested most frequently along the southern half of the island. This is consistent with results of pre-vious surveys.

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Leatherback turtle nest densities have remained low on Hutchinson Island; however, increased nesting during recent years (Figure 12) may reflect an overall in-crease in the number of nesting females in the Hutchinson Island area. During 1991, leatherback turtles primarily nested on the southern half of the island.

Intake Canal Monitorin Entrainment of sea turtles at the St. Lucie Plant has been attributed to the presumed physical attractiveness of the offshore structures housing the intake pipes rather than to plant operating characteristics (ABI, 1980b and 1986). The velocity caps supported above the openings to each intake pipe eliminate vertical water entrainment and substantially reduce current velocities near the structures by spreading horizontal draw over an arc of 360 . Thus, even when both units are operating at full capacity, turtles must actively swim into the mouth of one of the intake pipes before they en-counter current velocities sufficiently strong to effect entrainment. Consequently, a turtle's entrapment relates primarily to the probability that it will detect and subsequently enter one of the intake structures. Assuming that detection distances do not vary ap-preciably over time and that all turtles (or a constant proportion) are equally attracted to the structures, capture rates will vary proportionally to the number of turtles occur-ring in the vicinity of the structures.

Relative Abundance and Tem oral Distribution During 1991, 121 sea turtle captures took place in the intake canal of the St. Lucie Plant: 107 loggerheads, 12 green turtles, 1 hawksbill and 1 Kemp's ridley (Table 2). All but one of the five species of sea turtles inhabiting coastal waters of the southeastern 24

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United States were present. Since intake canal monitoring began in May 1976, 1,960 loggerhead (including 107 recaptures), 318 green (including 1 recapture), 9 leather-back, 9 hawksbill and 18 Kemp's ridley captures have taken place at the St. Lucie Plant.

Annual catches of loggerheads increased steadily from a low of 33 in 1976 (par-tial year of plant operation and monitoring) to 172 in 1979 (Figure 13). After declining between 1979 and 1981, yearly catches of loggerheads again rose steadily, reaching a high of 195 during 1986. Captures have been in decline since 1986, decreasing about 45 percent over the last five years.

Two offshore intake structures were in place prior to Unit 1 start-up in 1976; the third and largest structure was installed during 1982-1983. Even though all three struc-tures are in relatively close proximity, the addition of another pipe may have 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. Ad-ditionally, the influence of the construction itself on sea turtle entrainment during 1982 and 1983 is unknown. Similarly, damage to the center portions of two of the three velocity caps was observed in 1989. This damage added a strong vertical component to water entrainment. Following a thorough evaluation of the extent and cause(s) of the damage, a major repair operation was undertaken during 1991. The degree to which a shift in entrainment characteristics and subsequent repair operations affected sea turtle entrapment is also unknown. With these considerations in mind, neither a long-term increase nor decrease in the number of loggerheads captured at the St. Lucie Plant can be inferred from the data.

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During 1991, the monthly catch of loggerheads ranged from 1 (November and December) to 20 (March), with a monthly mean of 8.9 (+7.0; Table 3). The number of captures during March, April and May were considerably above average, while cap-tures throughout the remainder of the year were slightly to considerably lower than average (Figure 14). Over the entire monitoring period, monthly catches have ranged from 0 to 39; the greatest number of captures occurred during January 1983.

When data from all full years of monitoring (1977-1991) were combined, the highest number of loggerhead captures occurred in January; fewest captures were recorded in November and December (Table 3). However, monthly catches have shown considerable annual variability. Months having relatively low catches one year often have had relatively high catches in another.

Catches of green turtles also have varied widely among years, ranging from 0 in 1976 (partial year of sampling) to 69 in 1984 (Figure 13; Table 4). During 1991, 12 in-dividuals were captured. The average annual catch of green turtles, excluding 1976, was 21.2 (+17.5). As for loggerheads, no long-term trends can be inferred from the data.

Green turtles have been caught during every month of the year, with average monthly catches for all years combined ranging from 0.4 in September to 6.7 in January (Table 4). Seasonal abundance patterns of green turtles were much more pronounced than for loggerheads, nearly 60 percent of all captures occurring during the three month period between January and March. During 1991, the largest number of green turtles 26

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(4) were captured in February. The most ever caught in one month was 37 in January 1984.

Catches of leatherbacks, hawksbills and Kemp's ridleys have been infrequent and scattered throughout the 16 year study period (Table 2). Each species has shown rather pronounced seasonal occurrences; all but two of the nine leatherbacks were collected between February and May, seven of the nine hawksbills were collected be-tween June and September, and all but two of the 18 Kemp's ridleys were caught be-tween November and April.

Size-Class Distributions Although several straight-line and curved measurements were recorded for turtles removed from the intake canal, only one straight-line measurement has been used in analyses presented here. 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). To date, loggerheads removed from the intake canal have ranged in length (SLCL) from 40.2 to 112.0 cm (x = 66.8 + 13.7 cm) and in weight from 10.7 kg to 169.6 kg (x = 49.3 + 31.1 kg; Figures 15 and 16).

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 (i.e., relative tail length) after attaining a somewhat larger size. In earlier annual reports, 80.0 cm was used as the lower limit for adult turtles. However, recent data suggest that some males may not mature, and thus might not-be distinguishable from females, until they are about 85.0 27

cm long. Based on these divisions, data were segregated into three groups: Juveniles

((70 cm), adults () 85 cm) and transitional (71-85 cm) The latter group probably in-

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cludes both mature and immature individuals.

Of the 1,848 loggerhead captures between 1977 and 1991 for which length data were recorded, 69.3 percent were juveniles, the majority of these measuring between 50 and 70 cm SLCL (Table 5). The remaining individuals were nearly equally divided between adults and animals in the transitional size class. Similar size-frequency dis-tributions, indicating a preponderance of juveniles, have been reported for loggerheads inhabiting the Mosquito/Indian River Lagoon (Mendonca and Ehrhart, 1982), the Canaveral ship channel (Henwood, 1987), and Georgia and South Carolina (Hillestad et al., 1982). These data suggest that coastal waters of the southeastern United States constitute an important developmental habitat for loggerhead sea turtles.

Seasonal patterns of abundance for various size classes indicated that juvenile loggerheads were slightly more abundant during the winter than at other times of the year (Table 5). About 47 percent of the juveniles wer'e captured between January and April. Abundances decreased in spring and remained relatively constant during the summer and early fall before decreasing again to lowest levels in November and December. The seasonal distribution of adult loggerheads was much more pronounced, 76 percent of all captures occurring between May and August. This rep-resents the major portion of the nesting season on Hutchinson Island.

Green turtles removed from the intake canal over the entire study period ranged in size from 20.0 to 108.0 cm SLCL(x = 35.8 + 14.0 cm) and 0.9 kg to 177.8 kg (x =

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9.3 + 19.9 kg; Figures 17 and 18). Nearly all (98 percent) were juveniles. About 80 per-cent were 40 cm or less in length, and 65 percent weighed 5 kilograms or less. Al-though these immature turtles exhibited distinct winter pulses, some small individuals were captured throughout the year (Table 4). To date, only eight adult green turtles (SLCL ) 83 cm; Witherington and Ehrhart, 1989) have been removed from the canal; all were captured during or shortly after the nesting season.

The nine hawksbills removed from the canal ranged in size from 34.0 to 83.4 cm SLCL (x = 50.3 + 17.3 cm) and in weight from 6.4 to 86.6 kg (x = 25.0 + 27.8 kg).

All but two were juveniles (SLCL < 63 cm; Witzell, 1983). Similarly, all but one of the 18 Kemp's ridleys captured at the St. Lucie Plant were juveniles (SLCL <60.0 cm; Hirth, 1980). Carapace lengths for the ridleys ranged from 27.0 to 62.0 cm SLCL (x = 37.0

+ 10.1 cm) and weights from 3.1 to 31.8 kg (x = 8.6 + 8.2 kg). The nine leather-backs removed from the canal ranged in length from 112.5 to 150.0 cm, and at least seven were adults (SLCL ) 121 cm; Hirth, 1980). The largest leatherback for which an accurate weight was obtained, a female with a curved carapace length of 158.5 cm,'eighed 334.8 kg.

Sex Ratios Since intake canal monitoring began in 1976, 282 adult loggerheads (SLCL > 85.0 cm) have been sexed. Females predominated males by a ratio of 5.3:1.0, which sig-nificantly departs from a 1:1 ratio (X, P < 0.05). Consequently, temporal patterns in the number of adult loggerhead captures were heavily influenced by the numbers of females present. When sexes were separated, it was evident that males were relative-29

ly evenly distributed among months, whereas almost 90 percent of the females were taken during the nesting season (May through September; Figure 19).

The number of adult female loggerheads captured at the St. Lucie Plant has in-creased noticeably since 1983. From 1977 (first full year of plant operation) through 1983, an average of 4.4 adult females (+ 3.2; range = 1-10) were entrapped each year, whereas since then, an average of 25.3 females per year were captured (+ 6.9; range = 16-35). This increase corresponds to a general rise in loggerhead nesting ac-tivity near the plant (Figure 20). Increased nearshore movement associated with nest-ing increases the probability of a turtle detecting one of the intake structures and hence the probability of entrainment. The sharp decline in captures during 1991 is probably related to the velocity cap repair project. Construction of the offshore platform and sub-sequent daytime repair activities may have reduced the attractiveness of the intake structures as a resting or staging area for adult females between successive nesting forays. Reduced association with the structures would decrease the likelihood of entrainment. Despite the recent decline in captures, the overall trend since 1983 sug-gests a genuine increase in the number of female loggerheads occurring in the vicinity of the plant.

Between September 1982 and December 1986, 267 individual juvenile and sub-adult loggerhead turtles captured in the canal were sexed by Texas A 8 M University researchers using a bioimmunoassay technique for blood serum testosterone. As pre-viously reported, females outnumbered males by a ratio of 2.3:1.0 (ABI, 1989). These findings are consistent with those reported for samples taken from the Cape Canaveral ship channel (1.7:1.0) and the Indian River Lagoon (1.4:1.0), where sex ratios are also 30

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significantly skewed in favor of females (WibbeIs et al., 1984). Blood samples collected since 1986 are currently being analyzed and these results will provide a valuable tool for assessing temporal variability in the sex ratios of the local loggerhead population.

Of the eight adult green turtles captured since monitoring began, six were males and two were females. Six immature green turtles have been sexed through blood work; all have been females. Of the six adult leatherback turtles for which sex was recorded, three were females and three were males. The two adult hawksbills and one Kemp's ridley were all females. No sex information exists for juveniles of any of these species.

Ca ture Efficiencies Capture methodologies have been under continual review and refinement as net materials, configurations and placement were varied in an effort to minimize sea turtle entrapment times. Concurrently, alternative capture techniques were evaluated and potential deterrent systems tested in the laboratory. During this period, capture efficien-cies varied in relation to netting effort and the effectiveness of the systems deployed:

A capture/recapture study conducted in the intake canal between October 1980 and January 1981 indicated that most turtles confined between the A1A bridge and the intake headwalls were captured within two weeks of their entrainment (ABI, 1983).

Based on more recent formal daily inspections, it appears that capture efficiencies have further improved. Nearly 50 percent of the turtles entering the canal are now caught within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of first sighting, and 90 percent are captured during their first week of entrapment (Figure 21). Average capture efficiency, expressed as elapsed days be-tween first sighting and capture, during the period from April 1990 through December

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1991 was 3.8 days (+ 5.9 days; range = 1-50 days). Better utilization of currents and eddies, adjustments to tethering lines, multi-net deployments and increased efforts to hand capture turtles have contributed to reduced entrapment times.

Entrapment times may be extended for turtles swimming past the A1A barrier net (ABI, 1987). Prior to barrier net repairs in 1990, the top of the net was occasionally sub-merged or the anchor cable pulled free from the bottom, allowing turtles wider than 30.5 cm to pass. Because capture efforts west of the A1A bridge were generally less effective than those near the intake headwalls, most turtles breaching the barrier net were not caught until they entered the intake wells of Units 1 and 2. Prior to installation of the UIDS barrier in 1986, about 15 percent of all turtles entrapped in the canal were removed from the intake wells. Because of their relatively small sizes, a much larger proportion of greens (51.6 percent) reached the plant than loggerheads (10.1 percent).

Since 1986, the percentage of greens caught at the intake wells has decreased to 33.3 percent, while all loggerheads have been prevented from reaching the plant. During 1991, only two of the 12 green turtle captures occurred at the intake wells.

During 1991, 98 percent of all turtles entrapped in the canal were captured east of the A1A bridge, 71 by netting and 48 by hand. The effective confinement of turtles east of A1A has been a major contributor to the high capture efficiency achieved during recent years.

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, 32

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wounds, injuries and any other abnormalities which might have affected overall vitality.

During 1991, 88.8 percent (95) of all loggerheads found in the canal were alive and in good to excellent condition. Only 10.3 percent (11) of loggerhead captures involved individuals in fair or poor condition; one loggerhead was dead when removed from the canal. Of the 12 green turtles removed from the intake canal during 1991, all but two were in good to excellent condition (one in fair condition and one in poor condition).

Over the entire monitoring period, about 77 and 78 percent, respectively, of all loggerhead and green captures have involved turtles in good to excellent condition (Table 6). Captures of individuals in fair to poor condition have occurred about 15 per-cent of the time for loggerheads and 14 percent of the time for greens. All of the hawksbills'and leatherbacks have been removed from the canal in good to excellent condition, while half of the Kemp's ridleys have fallen into these categories.

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 entrap-ment in the canal, at least as evidenced by physical appearance. Although ratings of fair or poor imply reduced vitality, the extent to which entrainment/entrapment is responsible is often indeterminable. In some instances, conditions responsible for lower ratings, such as injuries, obviously were sustained prior to entrainment.

During 1991, only four of the 107 loggerhead captures (3.7 percent) involved in-dividuals with noticeable injuries, such as missing appendages, broken or missing pieces of carapace and deep lacerations. Most of these were old, well-healed wounds, 33

and none were serious enough to require medical attention. None of the green turtles captured during 1991 had major injuries.

The majority of loggerheads rated as fair or poor during 1991 did not suffer from physical disabilities but rather appeared lethargic. Most were underweight and heavi-ly infested with barnacles and leeches. This condition, referred to as "diseased turtle syndrome" (Ehrhart, 1987) has been reported from several other locales and is unre-lated to a turtle's entrapment in the canal In two cases, the infirmity was so extreme

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that the animals were transferred to Sea World of Florida for treatment and rehabilita-tion. One was subsequently released, the other died in captivity.

Mortalities Sea turtle mortalities have been closely monitored throughout the life of the canal capture program in an attempt to assign probable causes and take appropriate remedial action to minimize future occurrences. Previous analyses of capture data iden-tified drowning in nets (A1A barrier net, UIDS barrier, and tangle nets), drowning in the intake pipes during periods of reduced intake flow, injuries sustained from dredging operations and injuries sustained from the mechanical rakes used in the intake wells as probable mortality factors (ABI, 1987). Although difficultto quantify, the entrapment and subsequent demise of injured or sick turtles has probably accounted for a portion of observed mortalities.

Over the entire 16 year monitoring period, 128 (6.5 percent) of the 1,960 logger-heads and 21 (6.6 percent) of the 318 green turtles entrapped in the canal were found dead (Table 6). Mortalities spanned the range of size classes for loggerheads (SLCL 34

= 47.5-103 cm), while all green turtle mortalities involved juveniles less than 42 cm in length. The four Kemp's ridley mortalities documented at the plant during 1987 and 1988 were the only deaths for this species to date; no leatherback or hawksbill mor-talities have occurred at the St. Lucie Plant.

Modifications to capture procedures, improvements to the A1A barrier net and virtual elimination of low flow conditions within the canal have resulted in a substantial reduction in sea turtle mortalities over the life of the canal capture program. Mortality rate, expressed as the percentage of total captures involving dead animals, declined nearly 50 percent between the first (1976-1983) and second (1984-1991) halves of the program (Table 2). During 1991, only one mortality, a loggerhead, was documented.

This represents the lowest annual mortality rate (<1.0 percent of total captures) since the canal capture program began and continues the declining trend referenced above.

The dead loggerhead removed from the canal in 1991 was found floating at the A1A barrier net. No apparent physical injuries were noted. Because of its advanced stage of decomposition, no necropsy was performed, and cause of death could not be determined.

Reca ture Incidents Since the St. Lucie Plant capture program began, most turtles removed from the intake canal have been tagged and released into the ocean at various locations along Hutchinson Island. Consequently, individual turtles can be identified as long as they retain their tags. Over the 16 year history of turtle entrapment at the St. Lucie Plant, 64 individuals (63 loggerheads and 1 green) have been removed from the canal more than 35

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once. Several other turtles with tag scars have also been recovered, indicating that the actual number of recaptures may be higher.

Of the 63 individual loggerheads known to have been caught more than once, 43 were caught twice, 10 were caught three times, 4 were caught four times, 2 were cap-tured five times, 2 were captured six times, 1 was caught seven times and 1 was caught on nine separate occasions, yielding a total of 107 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 returned. 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). As for overall captures, the majority of recapture incidents in-volved juveniles (SLCL <70 cm).

Recapture intervals for loggerheads ranged from four to 858 days, with a mean of 149 days (+ 169.4 days). The only green turtle caught more than once was captured I

on two occasions, returning to the canal 59 days after first being released into the ocean. About 57 percent of all loggerhead recapture incidents occurred within 90 days of previous capture and 90 percent within one year (Figure 22). The average interval between first and last capture was 257 days (+325.2 days). The longest period be-tween first and last capture was 5.3 years. These data suggest that residency times of loggerheads within the nearshore habitat adjacent to the St. Lucie Plant are relatively short. Similar findings have been reported for loggerheads inhabiting the Mosquito/In-dian River Lagoons of east-central Florida (Mendonca and Ehrhart, 1982).

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SUMMARY

A gradient of increasing loggerhead turtle nest densities from north to south along the northern half of Hutchinson Island has been shown during most survey years. This gradient may result from variations in beach topography, offshore depth contours, dis-tribution 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 nighttime construction activities associated with installation of power plant intake and discharge structures. Nesting returned to normal or above normal levels following both periods of construction. During 1991, daytime construction activities associated with velocity cap repairs had no apparent effect on nesting. Statistical analyses indicate that power plant operation, exclusive of nighttime construction, has had no significant effect on nest densities near the plant.

There have been considerable year-to-year fluctuations in loggerhead nesting ac-tivity on Hutchinson Island from 1971 through 1991. Fluctuations are common at other rookeries and may result from non-annual re'productive behavior. Despite these fluc-tuations, loggerhead nesting activity has remained high during recent years and may reflect an overall increase in the number of nesting females in the Hutchinson Island area. No relationship between total nesting on the island and power plant operation or intake/discharge construction was indicated.

Temporary declines in loggerhead nesting activity have been attributed to cool water intrusions that frequently occur over the continental shelf of southeast Florida.

Though temporal nesting patterns of the Hutchinson Island population may be in-37

fluenced by natural fluctuations in water temperature, no significant effects due to power plant operation have been indicated.

Since nesting 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 over-all predation rates in the nine survey areas have not exceeded ten percent since 1979.

Decreased predation by raccoons probably reflects a decline in the raccoon popula-tion.

During 1991, 47 green turtle and 44 leatherback turtle nests were recorded on Hutchinson Island. Nesting activity by these two species exhibited considerable annual fluctuations, as has been recorded at other rookeries, but has remained relatively high during recent years. This may reflect an overall increase in the number of nesting green and leatherback turtles in the Hutchinson Island area.

During 1991, 107 loggerheads, 12 green turtles, 1 hawksbill and 1 Kemp's ridley were removed from the St. Lucie Plant intake canal. Since monitoring began in May 1976, 1,960 loggerhead, 318 green, 9 leatherback, 9 hawksbill and 18 Kemp's ridley turtles 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 monitoring) to a high of 195 in 1986. Yearly catches of green turtles have ranged from 0 in 1976 to 69 in 1984. Differences in the number of turtles entrapped during different years and months are attributed primarily to natural variation in the occurrence of turtles 38

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in the vicinity of the offshore intake structures, rather than to plant operating charac-teristics.

Size-class distributions of loggerhead turtles removed each year from the canal have consistently been predominated by juveniles between 50 and 70 cm in straight line carapace length. Most green turtles entrapped in the canal (about 80 percent) were juveniles 40 cm or less in length. For both species, the largest number of captures for all years combined occurred during the winter, but these seasonal peaks were much more pronounced for green turtles. Sex ratios of both adult and immature loggerheads caught in the canal continued to be biased towards females.

During 1991, about 93 and 80 percent, respectively, of all loggerheads and green turtles removed from the canal were categorized by physical appearance as being in good to excellent condition. Over the entire 16 year monitoring period, 77 and 78 per-cent, respectively, of all loggerhead and green turtle captures have involved individuals in these categories; 15 percent of the loggerheads and 14 percent of the green turtles removed from the canal have been in fair or poor condition.

Only four percent of the turtles removed from the intake canal during 1991 had substantial injuries, and most of those were apparently sustained prior to entrapment.

Once in the canal, turtles confined east of A1A typically had very brief residency times.

Thus the relative condition of most turtles was not affected by their entrapment.

During 1991, one loggerhead mortality occurred in the intake canal. Cause of death could not be determined. Program modifications, including continual surveillance of tangle nets during periods of deployment, improvements to the integrity of the A1A 39

barrier net and greater effort to hand capture turtles have contributed to a substantial decline in sea turtle mortalities during recent years.

40

C I

I I

I

LITERATURE CITED ABI (Applied Biology, Inc). 1977. Ecological monitoring at the Florida Power & Light Co. St.

Lucie Plant, annual report1976. Volumes I and II. AB-44. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

. 1978. Ecological monitoring at the Florida Power & Light Co. 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. Lucie Plant annual non-radiologi-cal environmental monitoring report 1978. Volumes II and III, Biotic monitoring. AB-177. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Miami.

~ 1980a. Florida Power & Light Company, St. Lucie Plant annual non-radiologi-cal environmental monitoring report 1979. Volumes II and III, Biotic monitoring. AB-244. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

. 1980b. Turtle entrainment deterrent study. AB-290. Prepared by Applied Biology, Inc. for Florida Power & Light CoMiami.

. 1981a. Successful relocation of sea turtle nests near the St. Lucie Plant, Hutchinson Island, Florida. AB-317. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Miami.

. 1981 b. Florida Power & Light Company, St. Lucie Plant annual non-radiologi-cal environmental monitoring report 1980. Volumes II and III, Biotic monitoring. AB-324. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

. 1981c. Proposed St. Lucie Plant preoperational and operational biological monitoring program - August 1981. AB-358. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

. 1982. Florida Power & Light Company, St. Lucie Plant annual non-radiologi-cal environmental monitoring report 1981. Volumes II and III, Biotic monitoring. AB-379. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

. 1983. Florida Power & Light Company, St. Lucie Plant annual non-radiologi-cal aquatic monitoring report 1982. Volumes I and II. AB-442. Prepared by Applied Biol-

)e ogy, Inc. for Florida Power & Light Co., Miami.

I I

I I

~)

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 Unit 2 annual environ-mental operating report 1983. AB-533. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

. 1985a. Florida Power & Light Company, St. Lucie Plant annual non-radiologi-cal environmental monitoring report 1984. AB-553. Prepared by Applied Biology, Inc.

for Florida Power & Light Co., Juno Beach.

. 1985b. Florida Power & Light Company, St. Lucie Unit 2 annual environ-mental operating report 1984. AB-555. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Juno Beach.

. 1986. Florida Power & Light Company, St. Lucie Unit 2 annual environmen-tal operating report 1985. AB-563. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

i . 1987. Florida Power & Light Company, St. Lucie Unit 2 annual environmen-tal operating report 1986. AB-579. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

. 1988. Florida Power & Light Company, St. Lucie Unit 2 annual environmen-tal operating report 1987. AB-595. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

. 1989. Florida Power & Light Company, St. Lucie Unit 2 annual environmen-tal operating report 1988. AB-596. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

. 1990. Florida Power & Light Company, St. Lucie Unit 2 annual environmen-tal operating report 1989. AB-603. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

. 1991. Florida Power & Light Company, St. Lucie Unit 2 annual environmen-tal operating report 1990. AB-610. Prepared by Applied Biology, Inc. for Florida Power

& Light Co., Juno Beach.

g 42 I

I I

I I

Baldwin, W.P., Jr. and J.P. Lofton, Jr. 1959. The loggerhead turtles of Cape Romain, South Carolina. Previously unpublished manuscript abridged and annotated by D.K. Caldwell, without the authors. In D.K. Caldwell and A. Carr, coordinators, The Atlantic logger-head sea turtle, Caretta caretta caretta (L.), in America. Bulletin of the Florida State Museum, Biological Sciences, 4(10):319-348.

Bellmund, S., M.T. Masnik and G. LaRoche. 1982. Assessment of the impacts of the St. Lucie 2 Nuclear Station on threatened or endangered species. US Nuclear Regulatory Com-mission, 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 chemical factors affecting hatching in the green sea turtle, Chelonia ~mdas (L.). Ecology 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 Scien-ces 25(4):287-302.

C aldwell, D.K., A. Carr and L.H. Ogren. 1959. Nesting and migration of the Atlantic logger-head turtle. In D.K. Caldwell and A. Carr, coordinators, The Atlantic loggerhead sea turtle Caretta caretta ~carett (L.), in America. Bulletin of the Florida State'useum, Biological Sciences, 4(10):295-308.

Camp, D.K., N.W. Whiting and R.E. Martin. 1977. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. V. Arthropods. Florida Marine Research Publications 25:

1-63.

Carr, A., A. Meylan, J. Mortimer, K. Bjorndal and T. Carr. 1982. Surveys of sea turtle popula-tions and habitats in the Western Atlantic. NOAATechnical Memorandum NMFS-SEFC-91:1-82.

Davis, G.E., and M.C. Whiting. 1977. Loggerhead sea turtle nesting in Everglades National Park, Florida, U.S.A. Herpetologica 33:18-28.

gi 9 A.yy idyg 6 di gti i gy d iti Atoll It,~g t imbricata L., on Cousin Island, Seychelles. Biological Conservation 9:199-215.

t g

43 L

Ehrhart, L.M. 1979. Reproductive characteristics and management potential of the sea turtle rookery at Canaveral National Seashore, Florida. Pages 397-399 in Linn, R.M., ed.

Proceedings of the First Conference on Scientific Research in the National Parks, 9-1 2 November, 1976, New Orleans, La. NPS Trans. and Proc. Ser. No. 5.

. 1980. Threatened and endangered species of the Kennedy Space Center: marine turtle studies. In A continuation of baseline studies for environmentally monitoring space transportation systems (STS) at John F. Kennedy Space Center. Contract No.

NAS-10-8986. Vol. IV, NASA Report 163122. September 1980.

. 1987. Marine turtle mortality in the vicinity of Port Canaveral, Florida, 1977-84. In W.N.

Witzell, editor, Ecology of East Florida Sea Turtles, pages 1-20. NOAATechnical Report NMFS 53.

Ernest, R.G., R.E. Martin, B.D. Peery, D.G. Strom, J.R. Wilcox and N.W. Walls. 1988. Sea turtle entrapment at a coastal power plant. Pages 270-301 in Mahadevan, K., R.K. Evans, P.

Behrens, T. Biffar and L. Olsen, eds. Proceedings, Southeastern Workshop on Aquatic Ecological Effects of Power Generation. Report No. 124, Mote Marine Laboratory, Sarasota, Florida.

Ernest, R.G., R.E. Martin, N.W. Walls and J.R. Wilcox. 1989. Population dynamics of sea turtles E ~ ~ ~

~

utilizing shallow coastal waters off Hutchinson Island, Florida. Pages 57-59 in Eckert,

~

L S.A., K.L. Eckert and T.H. Richardson, compilers. Proceedings of the Ninth Annual

~

Workshop on Sea Turtle Conservation and Biology. NOAA Technical Memorandum

~

NMFS-SEFC-232.

Fowler, L.E. 1979. Hatching success and nest predation in the green sea turtle, Chelonia

~mdas at Tortuguaro, Costa Rica. Ecology 60(5):945-955.

Frazer, N.B. 1989. Nesting cycles in sea turtles: typical, but not cycles. Pages 61-64 in Eck-ert, S.A., K.L. Eckert and T.H. Richardson, compilers. Proceedings of the Ninth Annual Workshop on Sea Turtle Conservation and Biology. NOAA Technical Memorandum NMFS-SEFC-232.

i Futch, C.R. and S.E. Dwinell. 1977. Nearshore marine ecology 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, Florida: 1971-1974.

II. Sediments. Florida Marine Research Publications 23: 6-24.

i Gallagher, R.M. and M.L. Hollinger. 1977. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. I. Introduction and rationale. Florida Marine Research Publications

) 23: 1-5.

44 I

I I

I

Gallagher, R.M., M.L. Hollinger, R.M. Ingle and C.R. Futch. 1972. Marine turtle nesting on Hutchinson Island, Florida in 1971. Florida Department of Natural Resources, 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.

Henwood, T.A. 1987. Movements and seasonal changes in loggerhead turtle, Caretta caret-ta aggregations in the vicinity of Cape Canaveral, Florida (1978-84). Biological Con-servation 40:191-202.

Hillestad, H.O., J.l. Richardson, C. McVea, Jr. and J.M. Watson, Jr. 1982. Worldwide inciden-tal capture of sea turtles. Pages 489-496 in Bjorndal, K.A., ed. Biology and conserva-tion of sea turtles. Smithsonian Institution Press, Washington, D.C.

Hirth, H.F. 1980. Some aspects of the nesting behavior and reproductive biology of sea turtles.

American Zoologist 20:507-523.

Hopkins, S.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 i Conference of Southeastern Fish and Wildlife Agencies 32:213-223.

Hughes, G.R. 1974. The sea turtles of southeast Africa, 1 Status, morphology and distribu-

~

tions. South African Association for Marine Biological Research, Oceanographic Research Institute, Investigational Report No. 35:1-144.

. 1976. Irregular reproductive cycles in the Tongaland loggerhead sea turtle, Caretta caretta (L.) (Cryptodira:Chelonidae). Zoologica Africana 11(2):285-291.

Lyons, W.G. 1989. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. Part XI. Mollusks. Florida Marine Research Publication 47:1-131.

Martin, R.E., R.G. Ernest, N.W. Walls and J.R. Wilcox. 1989a. Size distribution and seasonal abundance of loggerhead and green turtles in nearshore waters off Hutchinson Island, Florida. Pages 334-335 in Ogren, L., F. Berry, K. Bjorndal, H. Kumpf, R. Mast, G.

Medina, H. Reichart and R. Witham, editors. Proceedings of the Second Western At-lantic Turtle Symposium. Mayaguez, Puerto Rico, 12-16 October 1987. NOAA Techni-i cal Memorandum NMFS-SEFC-226.

. 1989b. Long-term trends in sea turtle nesting on Hutchin-son Island, Florida. Pages 111-113 in Eckert, S.A., K.L. Eckert and T.H. Richardson, t compilers. Proceedings of the Ninth Annual Workshop on Sea Turtle Conservation and

)0 Biology. NOAA Technical Memorandum NMFS-SEFC-232.

45 t

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I

Mendonca, M.T. and L.M. Ehrhart. 1982. Activity, population size and structure of the imma-ture ~h~lni ~m~d.q and ~Cretta garetta in Mosquito Lagoon, Florida. Cope is 1982:(1) 161-167.

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 Conservation of Sea Turtles. Smithsonian Institution Press. Washington, D.C.

NMFS (National Marine Fisheries Service). 1978. Final EIS listing and protecting the green sea I I ~li d <<h E d g dSp al Marine Fisheries Service, Dept. of Commerce, Washington, D.C.

i A t1973 N.

turtle (Chelonia ~mdas, loggerhead sea turtle (Caretta ~caretta and the Pacific Ridley

~Li NRC (US Nuclear Regulatory Commission). 1982. Final environmental statement related to the operation of St. Lucie Plant Unit 2. Docket No. 50-389.

O'ara, J. 1980. Thermal influences on the swimming speed of loggerhead turtle hatchlings.

~ ~

Copeia 1980(4):779-780. ~

Owens, D.W., J.R. Hendrickson, V. Lance and I.P. Callard. 1978. A technique for determin-ing sex of immature Chelonia ~mdas using a radioimmunoassay. Herpetologica 34:270-273.

Owens, D.W. and G.J. Ruiz. 1980. New methods of obtaining blood and cerebrospinal fluid from marine turtles. Herpetologica 36:17-20.

Pritchard, P.C., P.R. Bacon, F.H. Berry, A.F. Carr, J. Fletemeyer, R.M. Gallagher, S.R. Hop-kins, R.R. Lankford, R. Marques M., L.H. Ogren, W.G. Pringle, Jr., H.A. Reichart and R. Witham. 1983. IVlanuai of sea turtle research and conservation techniques. Prepared for the Western Atlantic Turtle Symposium, San Jose, Costa Rica, July 1983. 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 opera-tion on the nesting of the loggerhead sea turtle (Caretta ~caretta:1971-1984. Copeia 1986(3): 813-816.

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

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Routa, R.A. 1968. Sea turtle nest survey of Hutchinson Island, Florida. Quarterly Journal Florida Academy of Sciences 30(4):287-294.

Schulz, J.P. 1975. Sea turtles nesting in Surinam. Zoologische Verhandelingen, 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 practice of statistics in biologi-cal research. W.H. Freeman and Company, San Francisco. 859 pp.

Stancyk, S.E. 1982. Non-human predators of sea turtles and their control. Pages 139-152 in Bjorndal, K.A., ed. Biology and Conservation of Sea Turtles. Smithsonian Institution Press. Washington, D.C.

Talbert, O.R., S.E. Stancyk, J.M. Dean and J.M. Will. 1980. Nesting activity of the loggerhead turtle (Caretta~caretta in South Carolina. I: A rookery in transition. Copeia 1 980:(4)709-718.

Taylor, C.B., and H.B. Stewart. 1958. Summer upwelling along the east coast of Florida. Jour-nal of Geophysical Research 64(1):33-40.

Tester, L.A. and K.A. Steidinger. 1979. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. Vll. Phytoplankton, 1971-1973. Florida Marine Research Publica-tions 34: 16-61.

Walker, L.M. 1979. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. IX.

Diel plankton, 1973-1974. Florida Marine Research Publications 34: 99-117.

Walker, L.M., B.M. Glass and B.S. Roberts. 1979. Nearshore marine ecology at Hutchinson Island, Florida: 1971-1974. Vill. Zooplankton, 1971-1973. Florida Marine Research Publications 34: 62-98.

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

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

47

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Williams-Walls, N., J. O'ara, R.M. Gallagher, D.F. Worth, B.D. Peery and J.R. Wilcox. 1983.

Spatial and temporal trends of sea turtle nesting on Hutchinson Island, Florida, 1971-1979. Bulletin of Marine Science 33(1):55-66.

Witherington, B.E. and L.M. Ehrhart. 1989. Status and reproductive characteristics of green turtles (Qhel~oni ~mdas nesting in Florida. Pages 35t-352 in Ogren, L., F. Berry, K.

Bjorndal, H. Kumpf, R. Mast, G. Medina, H. Reichart and R. Witham, editors. Proceed-ings of the Second Western Atlantic Turtle Symposium. Mayaguez, Puerto Rico, 12-16 October 1987. NOAA Technical Memorandum NMFS-SEFC-226.

Wit II WN 199393 9 I it i I pi Id tk 3 3 till I ~Eh I (Linnaeus, 1766). FAO Fisheries Synopsis, 137:1-78.

Worth, D.F. and M.L. Hollinger. 1977. Nearshore marine ecology at Hutchinson Island, Florida:

1971-1974. III. Physical and chemical environment. Florida Marine Research Publica-tions 23: 25-85.

Worth, D.F., and J.B. Smith. 1976. Marine turtle nesting on Hutchinson Island, Florida, in 1973.

Florida Marine Research Publications 18:1-17.

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48

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10 10 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH OF CAPTURE Figure 14. Mean number of loggerheads captured each month, St. Lucie Plant intake canal, 1977-1990, compared with number of monthly captures during 1991. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1%I values.

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No data collected for 82 individuals.

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No data collected for 10 individuals.

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No data collected for 14 individuals.

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20 20 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH OF CAPTURE Figure 19. Numbers of adult loggerheads (SLCL>85.0 cm), including recaptures, removed each month from the intake canal, St.

Lucie Plant, 1976-1991 (N=278; sex not recorded for 4 individuals >85.0 cm).

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10 zz 100 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 Figure 20. Comparison of captures of adult female loggerheads (SLCL>85.0 cm) in the intake canal, St. Lucie Plant, 19774991, and numbers of loggerhead emergences in area 4 adjacent to the plant. Nesting activity was not monitored in 1978.

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1OO 100 ILJ K

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(0 80 80 9

0 Z

60 60 0

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Uj 40 40 I-O 20 20 10 20 30 40 50 DAYS BETWEEN FIRST SIGHTING AND CAPTURE Figure 21. Capture efficiency, expressed as days between first sighting and capture, for loggerhead turtles entrapped in the intake canal, St. Lucie Plant, April, 1990-December, 1991. (N=119).

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vr' tu 80 80 (9

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~ 60 / 60 9

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I I 0 -0 Interval between successive captures 20 I 20 I Interval between first and last capture 250 500 750 1000 1250 1500 1750 RECAPTURE INTERVAL(days)

Figure 22. Cumulative percentage of all loggerhead recaptures occurring within various time intervals between successive captures (N=105) and first and last capture (N=61), St. Lucie Plant intake canal 1976-1991.

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TABLE 1 ESTIMATES OF THE NUMBERS OF LOGGERHEAD TURTLE NESTS ON HUTCHINSON ISLAND BASED ON SURVEYS OF NINE 1.25-KM-LONG SURVEY AREAS, 1971 - 1991, COMPARED TO THE ACTUALNUMBER OF NESTS ON THE ISLAND, 1981 - 1991 Extrapolation from the Actual number Number of nests in the nine nine survey areas to the of nests on the 1971 1420 4180 1973 1260 3709 1975 1493 4395 1977 932 2744 1979 1449 4266 1981 1031 3035 3115 1982 1634 4810 1983 1592 4687 4743 1984 1439 4236 4277 1985 1623 4778 4877 1986 1839 5414 5483 1987 1645 4843 4623 1988 1701 5008 4990 1989 1774 5223 5193 2177 6409 6700 1991 2409 7092 6812

TABLE 2 TOTAL NUMBER OF SEA TURTLE CAPTURES AND (NUMBER OF DEAD) TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976-1991 1976 33(4) 33(4) 1977 80(5) 5(2) 86(7) 1978 138(19) 6(1) 148(20) 1979 172(13) 3(1) 175(14) 1980 116(5) 10(3) 126(8) 1981 62(5) 32(2) 97(7) 1982 101(16) 8 110(16) 1983 119(4) 23(4) 142(8) 1984 148(3) 69(2) 220(5) 1985 157(4) 14 172(4) 1986 195(27) 22(1) 1 220(28) 1987 175(11) 35 6(2) 218(13) 1988 134(6) 42(2) 5(2) 181(10) 1989 111(4) 17(1) 2 133(5) 1990 112(1) 20(2) 132(3) 1991 107(1) 12 1 1 121(1)

Total 1960(128) 318(21) 9(0) 9(0) 18(4) 2314(1 53)

Annual Mean~ 128.5 21.2 0.6 0.6 1.2 152.1 Excludes 1976 (partial year of plant operation).

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TABLE 3 TOTAL NUMBER OF (AND NUMBER OF DEAD) LOGGERHEAD TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976-1991 1976 7(1) 2 1 7 5(3) 9 33(4) 1977 13 8(1) 7 5(2) 1 3 15(1) 9(1) 5 5 80(5) 1978 19 11(2) 27(2) 19(5) 3(1) 10 12 1 17(2) 15(7) 4 138(19) 1979 24(3) 29(1) 11 17 0 3(1) 27(2) 16(2) 8(1) 15(3) 12 10 172(13) 1980 16 21(2) - 14 8(3) 12 19 116(5) 1981 11(1) 11(3) 6 10 6 1 6 2(1) 0 0 62(5) 1982 6(2) 14 14 17(4) 7 7 2(1) 9(1) 9(5) 4(2) 101(16) 1983 39 13(1) 1 0 4 7(1) 7 6 8(2) 17 5 12 119(4) 1984 13 11 6 2(1) 7 28(1) 12(1) 26 16 10 9 148(3) 1985 11 15 20 13 16 17 20(3) 19(1) 14 7 3 157(4) 1986 15(2) 16(4) 14(4) 20(2) 12 20(1) 26(2) 34(6) 9(4) 11(2) 8 10 195(27) 1987 26(3) 11 8(1) 24(3) 23(1) 26(1) 19(1) 17(1) 4 3 5 175(11) 1988 10(3) 11 13(2) 28 30 5 3 11(1) 2 5 134(6) 1989 13 4(2) 11 13 16 21(1) 15 2 3 5(1) 111(4) 1990 9 9 23 25 16 .

7(1) 112(1) 1991 13 12 20 19 15 11 6 3 2(1) 4 107(1)

Total 232(11) 190(17) 172(9) 176(15) 177(6) 219(8) 178(11) 180(11) 128(13) 125(13) 87(13) 96(1) 1960(128)

Monthly Mean 15.5 12.7 11.5 11.7 11.1 13.7 11.1 11.3 8.0 7.8 5.4 6.0

%Total Catch 12.0 9.9 8.9 9.1 9.1 11.4 8.9 9.2 6.6 ~

6.1 4.3 4.5 Excludes 1976 (partial year of plant operation).

TABLE 4 TOTAL NUMBER OF (AND NUMBER OF DEAD) GREEN TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976-1991 1976 1977 2 2(1) 5(2) 1978 1 2 6(1) 1979 0 1 3(1) 1980 0 5(1) 4(1) 10(3) 1981 20(1) 7 2(1) 32(2) 1982 1 0 1983 8(1) 4 3(2) 4(1) 23(4) 1984 37(1) 10 4(1) 69(2) 1985 1986 6(1) 22(1) 1987 4 1 3 3 3 1 5 11 35 1988 12 11 4 2 3 6(2) 0 2 42(2) 1989 3(1) 0 6 3 1 1 0 0 2 17(1) 6(1) 3(1) 3 1 1 1 0 2 1 20(2) 1991 1 4 2 1 0 0 0 1 1 12 Total 100(5) 52(3) 35(4) 20(2) 9(1) 18(3) 8 9(1) 15 21(2) 25 318(21)

Monthly Mean 6.7 3.3 2.3 1.3 0.6 1.1 0.5 0.6 04 0.9 1.3 1.6

% Total Catch 31.4 16.4 11.0 6.3 2.8 5.7 2.5 2.8 1.9 4.7 6.6 7.9

TABLE 5 NUMBER OF MONTHLYCAPTURES BY SIZE CLASS FOR LOGGERHEAD TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT, 1977-1991 Size classes (SLCL in cm)

January 16 14.8 26 9.2 10 3.5 February 12 152 11.9 21 7.4 2 2 1.4 March 8 74 53 135 10.5 20 7.0 1 6 3.2 April 15 53 57 125 9.8 30 10.6 2 6 2.8 May 12 58 40 110 8.6 17 6.0 15 28 15.6 June 12 50 106 8.3 29 10.2 44 27 74 26.2 July 35 6.5 29 10.2 23 30 57 20.2 August 7 48 98 7.6 36 12.7 19 19 39 13.8 September 4 50 38 92 7.2 16 5.6 5 8 15 5.3 October 35 35 78 6.1 28 9.9 5 1 2.5 November 4 21 24 49 3.8 19 67 10 3.2 December 4 34 26 5.0 13 46 2.1 Total 106 540 1282 129 138 15 282

% of Total 69.3 15.4 15.3 Excludes 1976 (partial year of data).

No data were collected for 79 individuals.

W W W W TABLE 6 RELATIVE CONDITION OF SEA TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PIANT, 1976- 1991 Relative 431 22.0 134 42.1 1 11.1 3 16.7 7 77.8 576 24.9 549 28.0 61 19.2 1 11.1 3 16.7 2 22.2 616 26.6 522 26.6 53 16.7 7 77.8 3 16.7 585 25.3 231 11.8 36 11.3 3 16.7 270 11.7 72 3.7 8 2.5 2 11.1 82 3.5 128 6.5 21 6.6 4 22.2 153 6.6 27 1.4 5 1.6 32 1.4 Total 318 18 2314 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, debilitating wounds or missing appendages.

6 Dead 7 Alive but othenvise condition not recorded.