ML17223B174

St.Lucie Unit 2 Annual Environ Operating Rept,Vo1 1 for 1990.

ML17223B174
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Site:	Saint Lucie
Issue date:	12/31/1990
From:	APPLIED BIOLOGY, INC.
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AP P L I E D B I 0 L'0 6 Y, I N C. AB-610 I'LORIDA POWER & LIGHT COMPANY ST. LUCIE UNIT 2 ANNUAL ENVIRONMENTALOPERATING REPORT VOLUME I 1990 I 2968 A NORTH DECATUR ROAD ~ ATLANTA, GEORGIA 30033 ~ 404-296-3900 9105070294 910025 PDR ADOCK 05000389 R PDR

AB-610 FLORIDA POWER & LIGHT COMPANY ST. LUCIE UNIT 2 ANNUALENVIRONMENTAL OPERATING REPORT 1990 VOLUME 1 APRIL 1991 FLORIDA POWER & LIGHT COMPANY JUNO BEACH, FLORIDA APPLIED BIOLOGY, INC.

ATLANTA,GEORGIA

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ENVIRONMENTALOPERATING REPORT 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 14 Results and Discussion 15 Nesting Survey 15 Distribution of Loggerhead Nests Along Hutchinson Island 15 Estimates of Total Loggerhead Nesting on Hutchinson Island 18 Temporal Loggerhead Nesting Patterns 19 Predation on Loggerhead Turtle Nests 20 Green and Leatherback Turtle Nesting 21 Intake Canal Monitoring 23 Relative Abundance and Temporal Distribution 23 Size-Class Distributions 26 Sex Ratios . 28 Capture Efficiencies . 30 Relative Condition 31 Mortalities 33 Recapture Incidents 34 Summary 36 LITERATURE CITED 40 FIGURES 48 TABLES 70

TABLE OF CONVERSION FACTORS FOR METRIC UNITS To convert Multi I b To obtain centigrade (degrees) ( C x 1.8) + 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 x10 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 millimetc rs liters (I) 1.0 x 10 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 JJards 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

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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 There have been considerable year-to-year fluctuations in sea turtle nesting activity on Hutchinson Island since monitoring began in 1971. Low nesting activity in 1975 and 1981 -1983 in the vicinity of the power plant was attributed to construction of plant in-take and discharge structures. Nesting returned to normal or above normal levels fol-lowing both periods of construction. Power plant operation exclusive of construction has had no significant effect on nesting near the plant. Data collected through 1990 have shown no long-term reductions in total nesting, total emergences or nesting suc-cess on the island. Formal requirements to conduct this program expired in 1986 but were voluntarily continued in 1990 with agreement from federal and state agencies.

INTAKE CANAL MONITORING Since plant operation began in 1976, 2,193 sea turtles (including 100 recaptures) representing five different species have been removed from the intake canal. Eighty-four percent of these were loggerheads. Differences in the numbers of turtles found during different months and years were attributed to natural variation in the occurren-ces of turtles in the vicinity of the plant, rather than to any influence 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. Turtles confined between the A1A barrier net and intake headwalls usually resided in the canal for a relatively short period of time, and most were 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.

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 Commis-sion, 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,

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 January 1982, 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, 1981 c). 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 seven environmen-tal operating reports (ABI, 1984b, 1985b, 1986, 1987, 1988, 1989, 1990). This report describes the 1990 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.

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Hutchinson Island is a barrier island that extends 36 km between inlets and obtains its maximum width of 2 km at the plant site. Elevations approach 5 m atop dunes bor-dering the beach and decrease to sea level in the marigrove swamps that are common on much of the western side. Island vegetation is typical of southeastern Florida coas-tal areas; dense stands of Australian pine, palmetto, sea grape and Spanish bayonet are present at the higher elevations, and mangroves abound at the lower elevations.

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 con-sists primarily of sand and shell sediments. The unstable substrate limits the estab-lishment 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 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 the atmosphere.

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

4.2 Terrestrial A uatic Issues Issues on endangered or threatened sea turtles raised in the Unit 2 FES-OL [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. AII 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.

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 captul'B 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 caretta and also supports some nesting of the green turtle, Chelonia ~mdas and th I th 5 kt tl .~OI I I 19 15 II t 1.,1959;5 t,1995;9 I-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 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-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 construction activities conducted offshore from and perpendicular to the beach. Construction had been com-pleted and the plant was in full operation during the 1977 and 1979 surveys.

A modified daytime nesting survey was conducted in 1980 during the preliminary construction of the ocean discharge structure for St. Lucie Plant Unit 2. During this study, four of the previously established 1.25-km-long survey areas were monitored.

Additionally, eggs from turtle nests potentially endangered by construction activities were relocated.

Every year from 1981 through 1990, 36 1-km-long survey areas comprising the en-tire 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 l

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.

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 1990 with agreement from federal and state agencies. Results are presented in this report and discussed in relation to previous findings.

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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 integral 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 nesting surveys, nest relocation activities and canal capture program (Gallagher et al., 1972; Worth and Smith, 1976; ABI, 1978, 1980a, 1981a, 1982, 1983, 1984b, 1985b, 1986, 1987, 1988, 1989, 1990; 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 ther-mal discharges on hatchling swimming speed have also been reported (ABI, 1978; O'ara, 1980). The purpose of this report is to 1) present 1990 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 1990 canal capture data and summarize comparable data collected since 1976.

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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, 1981 a, 1982, 1987, 1988, 1989). Methods used during the 1990 survey were designed to allow comparisons with these previous studies.

On 11 and 13 April 1990, preliminary nest surveys were conducted along Hutchin-son Island from the Ft. Pierce Inlet south to the St. Lucie Inlet. From 16 April through 7 September, nest surveys were conducted on a daily basis. After 7 September, several additional surveys were conducted to confirm that nesting had ceased, the last survey being conducted on 14 September. Biologists used small off-road motorcycles to sur-vey the island each morning. New nests, non-nesting emergences (false crawls), and nests destroyed by predators were recorded for each of the 361-km-long survey areas comprising the entire island (Figure 3). The nine 1.25-km-long survey areas established by Gallagher et al. (1972) also were monitored so comparisons 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 10

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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 Maiine 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 1990 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-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.

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I 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.

In the past, the integrity of the barrier net was occassionally 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, but the net is constructed of heavy chain links rather than rope.

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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 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 should prove effective in confining 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 A1 A bar-rier net and UIDS barrier. Because of the reduction in total netting hours during 1990, increased effort was directed toward hand capture of turtles. This was accomplished by diving and use of dip nets, and it proved very effective when good water clarity con-ditions prevailed.

Regardless of capture method, all turtles removed from the canal were identified to species, measured, weighed, tagged, and examined for overall condition (wounds, 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 a local veterinarian. Resuscitation techniques were used if a turtle was found that appeared to have died recently. Beginning in 1982, necrop-13

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sies were conducted on dead turtles found in fresh condition; one necropsy was per-formed during 1990.

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 sub-ject 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 1990. 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), Texas A & M University, University of Rhode Island, University of South Carolina, University of Illinois, University of Central Florida, University of Geor-gia, Virginia Institute of Marine Science and the Western Atlantic Turtle Symposium.

Studies to Evaluate and or Miti ate Intake Entra ment A program that assessed 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

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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.

Since 1981, all 36 1-km-long segments comprising the island's coastline have been surveyed. Regardless of technique, loggerhead nest densities have shown con-siderable annual variation within individual survey areas (Figures 4 and 5). Yet, the annual spatial distribution of those nests among survey areas has produced a rather uniform gradient, nest densities consistently increasing from north to south (ABI, 1987).

The gradient appears to be linear when only the nine 1.25-km-long survey areas are used (Figure 4), but becomes non-linear when all 36 1-km-long survey areas are in-cluded in the analysis (Figure 5). During 1990 the distribution of loggerhead nests along the island was characterized by record high nesting along the northern and central por-tions of the island (Figure 5).

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

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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-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.

lo Historically, the pattern of loggerhead emergences on the island has generally paral-leled the distribution of nests (ABI, 1987, 1988), and this same trend was apparent in 1990 (Figure 6). In contrast, nesting success by loggerheads along the island has typi-P cally 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 1990 were generally high when compared with previously recorded values (Figures 4 and 5). Record high nesting was recorded in 21 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 nesting was due to record high emergence rates, and this may reflect an increase in the num-ber 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.

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. This trend continued during 1990 (Figure 8). Thus, power

plant operation exclusive of intake/discharge construction has had no apparent effect on nesting.

Data collected through 1990 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).

EstimatesofTotaILo erheadNestin onHutchinsonlsland Various methods were used during surveys prior to 1981 to estimate the total num-ber 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-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 1990 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 ten-year mean of 33.8 percent, estimates of the total number of nests on Hutchinson Island can be calculated by multiplying the number of nests in the nine areas by 2.96. This technique, when ap-plied to the nine survey areas during the ten years in which the entire island was sur-veyed, produced whole-island estimates within 5.3 percent of the actual number of 18

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nests counted. Because the proportion of nests recorded in the nine survey areas remained relatively constant over the last ten years, this extrapolation procedure should provide a fairly accurate estimate of total loggerhead nesting for years prior to 1981.

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 the overlapping of non-annual breeding populations. Nonetheless, data collected through 1990 suggest an overall increase in nesting on Hutchinson Is-land since surveys began in 1971. Total nesting activity was greatest during 1990 when 6,700 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 1990 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) suggested that these intrusions may have been responsible for the temporary declines in loggerhead turtle nesting activity previously observed on Hutchinson Is-19

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land. Similarly, a substantial decrease in nesting during mid-July 1990 was apparently due to an intrusion of cool water (Figure 10).

Though natural fluctuations in temperature have been shown to affect temporal nest-ing patterns on Hutchinson Island, there has been no indication that power plant opera-tion has affected these temporal patterns (ABI, 1988) ~

Predation on Lo erhead Turtle Nests Since nest surveys began in 1971, raccoon predation probably has been the major cause of turtle nest destruction on Hutchinson Island. Researchers at other locations have reported raccoon predation levels as high as 70 to nearly 100 percent (Davis and Whiting, 1977; Ehrhart, 1979; Hopkins et al., 1979; Talbert et al., 1980). Raccoon preda-tion 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 1990, six percent (406) of the loggerhead nests (n =6,700) on the island were depredated by raccoons. As in previous years (ABI, 1989), predation of turtle nests was primarily restricted to the most undeveloped portion of the island (i.e., Areas E through S; Figure 11).

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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 - 1989 (ABI, 1990). During 1990, 0.4 percent (27) of the loggerhead nests (n =6,700) on the island were destroyed 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 0.4 to 3.2 percent. During 1990, 1.4 percent (96 nests) were destroyed by either ghost crabs or a combination of ghost crabs and raccoons.

Green and Leatherback Turtle Nestin Gl'een and leatherback turtles also nest on Hutchinson Island, but in fewer numbers than loggerhead turtles. Prior to 1981, both survey (nine 1.25-km-long sections) and inter-survey areas were monitored for the presence of green and leatherback nests.

Thirty-one kilometers of beach from Area 1 south to the St. Lucie Inlet were included in that effort. During whole-island surveys from 1981 through 1990, only two of 182 Ieatherback nests and only seven of 601 green nests were recorded on the five kilometers of beach north of Area 1. Therefore, previous counts of green and leather-21

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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 1990, the number of nests observed on the island ranged from 5 to 74 for green turtles and from 1 to 36 for leatherbacks (Figure 12). During the 1990 survey, 132 green turtle and 12 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 1990, green turtles nested from 28 May through 11 September. Leatherback'turtles usually nest on the island from mid-April through early to mid-July. During 1990 this species nested from 10 April through 3 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 fluc-tuations in the numbers of green turtles nesting at other breeding grounds (Carr et al.,

1982). Despite these fluctuations, data collected through 1990 suggest an overall in-crease in nesting since 1971 and may reflect an increase in the number of nesting females in the Hutchinson Island area. During 1990, green turtles nestedmost frequent-ly along the southern half of the island. This is consistent with results of previous sur-veys.

Leatherback turtle nest densities have remained low on Hutchinson Island; however, increased nesting during recent years (Figure 12) may reflect an overall increase in the 22

number of nesting females in the Hutchinson Island area. During 1990, 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). Even when both units are operating at full capacity, turtles must actively swim into the mouth of one of the intake pipes before they encounter 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 distan-ces do not vary appreciably 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 occurring in the vicinity of the structures. If this assumption is true, data from the canal capture program should reflect natural variability in the structure of the popula-tion being sampled.

Relative Abundance and Tem oral Distribution During 1990, 132 sea turtle captures took place in the intake canal of the St. Lucie Plant (Table 2). Of the five species of sea turtles inhabiting coastal waters of the southeastern United States, only two were represented in this year's catches: 112 log-gerheads and 20 green turtles. Since intake canal monitoring began in May 1976, 1,853 loggerhead (including 99 recaptures), 306 green (including 1 recapture), 9 leatherback, 8 hawksbill and 17 Kemp's ridley captures have taken place at the St. Lucie Plant.

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Annual catches of loggerheads increased steadily from a low of 33 in 1976 (partial year of plant operation and monitoring) to 172 in 1979 (Figure 13). After declining be-tween 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 more than 40 percent over the last four 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 structures 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. Addition-ally, the influence of the construction itself on sea turtle entrainment during 1982 and 1983 is 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.

During 1990, the monthly catch of loggerheads ranged from 1 (November) to 25 (June), with a monthly mean of 9.3 (+7.0; Table 3). The number of captures during May, June and July were considerably above average, while captures throughout the I

remainder of the year were moderately 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 (1977-1990) were combined, the highest number of loggerhead captures occurred in January (11.8 percent); fewest captures 24

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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 (Table 4). During 1990, 20 individuals were captured. The average annual catch of green turtles, excluding 1976, was 21.9 (+18.0).

Although highly variable, annual capture data for green turtles suggest a long-term in-crease in the number of individuals inhabiting the nearshore coastal area adjacent to the plant (Figure 13). Again, however, the influence of the addition of a third intake pipe during 1982-1983 on these data is not known.

Green turtles have been caught during every month of the year, with average month-ly catches for all years combined ranging from 0.3 in September to 7.1 in January (Table 4). Seasonal abundance patterns of greens are much more pronounced than for log-gerheads, nearly 60 percent of all captures occurring during the three month period between January and March. During 1990, the largest number of greens (6) were cap-tured in January. The most greens 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 15 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 Bight hawksbills were collected between June and September, and all but two of the 17 Kemp's ridleys were caught between November and April.

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Size- lass Distrib tion 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 = 49.2 + 31.0 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 (e.g., relative tail length) after obtaining a length of about 85 cm. Previously, 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 attain a slightly larger size.

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 includes some mature and some immature individuals.

Of the 1,744 captures between 1977 and 1990 for which length data were collected, 69 percent were juveniles, the majority of these measuring between 50 and 70 cm SLCL (Table 5). Adults accounted for about 15 percent of all captures, with the remaining 16 percent comprised of animals in the transitional size class. Similar size-frequency distributions, indicating a preponderance of juveniles, have been reported for the 26

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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 Caretta caretta.

Seasonal patterns of abundance for various size classes indicated that juvenile log-gerheads were slightly more abundant during the winter than at other times of the year (Table 5). About 45 percent of the juveniles were 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 per-cent of all captures occurring between May and August, This represents the major pro-tion 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 + 14.3 cm) and 0.9 kg to 177.8 kg (x =

9.4 + 20.2 kg; Figures 17 and 18) Nearly all (96 percent) were juveniles. About 80 per-

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cent were 40 cm or less in length, and 66 percent weighed 5 kilograms or less. These immature turtles exhibited distinct winter pulses suggesting migratory behavior (Table 4). However, some immature green turtles were present throughout the year. To date, only eight adult green turtles (SLCL >83 cm; Witherington and Ehrhart, 1989) have been removed from the canal; ail were captured during or shortly after the nesting season.

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The eight hawksbills removed from the canal ranged in size from 34.0 to 70.0 cm SLCL (x = 46.2+ 12.9 cm) and in weight from 6.4 to 52.2 kg (x = 17.3 + 16.6 kg).

All but one were juveniles (SLCL <63 cm; Witzell, 1983). Similarly, all but one of the 17 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 = 36.1

+ 9.7 cm) and weights from 3.1 to 31.8 kg (x = 8.0 + 8.1 kg). The nine leatherbacks 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 ac-curate weight was obtained, a female with a curved carapace length of 158.5 cm, weighed 334.8 kg.

~Sx Ratios Since intake canal monitoring began in 1976, 255 adult loggerheads (SLCL > 85.0 cm) have been sexed. Females predominated males by a ratio of 5.4:1.0, 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 is evident that males were relatively evenly distributed among months, whereas 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 steadily over the last seven years. From 1977 through 1983, an average of 4.4 adult females (+ 3.2; range = 1-10) were entrapped each year, whereas since then, an average of 26.3 females per year (+ 6.7; range = 16-35) were captured. This in-28

crease corresponds to a general rise in loggerhead nesting activity near the plant (Figure 20). Increased nearshore movement associated with nesting increases the probability of a turtle detecting one of the intake structures and hence the probability of entrainment. Although the addition of the third offshore intake structure may have accounted for some of the increase in the number of adults entrained since 1983, the continued rise over the last seven years suggests a genuine increase in the number of females 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 re-searchers 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 significantly skewed in favor of females (Wibbels 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 adult hawksbill and Kemp's ridley were both females. No sex information exists for juveniles of these species.

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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 almost 90 percent are captured during their first week of entrapment (Figure 21). Average capture efficiency, expressed as elapsed days between first sighting and capture, during the period from April through Decem-ber 1990 was 3.9 days (+ 6.8 days; range = 1-50 days). Better utilization of currents and eddies, adjustments to tethering lines, multi-net deployments and increased ef-forts 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). Occasionally, the top of the net has been submerged or the anchor cable pulled free from the bottom, allowing larger turtles to pass; turtles with carapace widths less than about 30.5 cm can swim through the large mesh. Because capture efforts west of the A1A bridge have generally been less effective than those near the intake 30

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. Be-cause of their relatively small sizes, a much larger proportion of greens (51.6 percent) reached the plant than loggerheads (10.1 pel'cent). Since 1986, the percentage of greens caught at the intake wells has decreased slightly (35.1 percent), while all log-gerheads have been prevented from reaching the plant.

Major renovations were made to the A1A barrier net during 1990 to further reduce the potential for turtles larger than 30.5 cm becoming trapped between A1A and the UIDS. Two loggerheads (less than 2 percent of all loggerhead captures) breached the A1A barrier net prior to completion of these modifications. Both were removed from the canal at the UIDS barrier. Additionally, two small green turtles passed through the A1A barrier net and were removed at the plant's intake wells. Thus, nearly 97 percent of all turtles entrapped in the canal during 1990 were captured by netting or by hand east of the A1A bridge. The effective confinement of turtles east of A1A was another major contributor to the high capture efficiency achieved during 1990.

Relative Condition Turtles captured alive in the intake canal of the St. Lucie Plant were assigned a rela-tive condition based on weight, activity, parasite infestation, barnacle coverage, wounds, injuries and any other abnormalities which might have affected overall well-being. During 1990, 92.9 percent (104) of all loggerheads found in the canal were alive and in good to excellent condition. Only 6.3 percent (7) of loggerhead captures in-31

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volved individuals in fair or poor condition; one loggerhead was dead when removed from the canal. Of the 20 green turtles removed from the intake canal during 1990, 16 were in good to excellent condition, two were in fair condition and two were dead.

Over the entire monitoring period, about 76 and 78 percent, respectively, of all log-gerhead and green captures have involved turtles in good to excellent condition (Table 6). Captures of individuals in fair to poor condition have occurred about 16 percent 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 about 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 1990, about nine percent (10) of all loggerhead captures involved individuals with noticeable injuries, such as missing appendages, broken or missing pieces of carapace and deep lacerations. Most of these were old, well-healed wounds, and none were serious enough to require medical attention. None of the green turtles captured during 1990 had major injuries.

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~Mrtalitie Mortalities have been closely monitored throughout the life of the canal capture program in an attempt to assign probable causes and take appropriate remedial ac-tion to minimize future occurrences. Previous analyses of capture data identified drown-ing in nets (A1 A 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 mor-tality factors (ABI, 1987). Although difficultto quantify, the entrapment and subsequent demise of injured or sick turtles has probably accounted for a portion of observed mor-talities.

Over the entire 15 year monitoring period, 127 (6.9 percent) of the 1,853 logger-heads and 21 (6.9 percent) of the 306 green turtles entrapped in the canal were found dead (Table 6). Mortalities spanned the range of size classes for loggerheads (SLCL

= 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 wel'e 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 vir-tual 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 rates, expressed as the percentage of total captures involving dead animals, declined 42 percent between the first (1976-1983) and second (1984-1990) halves of the 33

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program. During 1990, only three mortalities (2.3 percent of total captures) were recorded, one loggerhead and two green turtles. This represents the fewest annual mortalities since the canal capture program began in 1976.

Previous observations suggest that sick or injured turtles may be susceptible to drowning at the UIDS barrier. The loggerhead mortality recorded during 1990 occurred at this location. Even though the carcass was too decomposed to assess its physical condition or determine cause of death, drowning is suspected. Additional improve-ments to the A1A barrier net during the later part of 1990 should prevent future logger-head movements west of A1A and thereby eliminate the UIDS barrier as a potential mortality source.

The two green turtle mortalities during 1990 resulted from drowning in ABI's tangle nets. One of these was resuscitated, but it later succumbed while under observation.

A necropsy was performed to determine if it was in poor health at the time of capture; results of tissue analyses have not yet been completed. To eliminate the potential for future net drownings, ABI has begun continual monitoring of its tangle nets during periods of deployment.

Reca ture Incident Since the St. Lucie Plant capture program began, most turtles removed alive 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 15 year history of turtle entrapment at the St. Lucie Plant, 61 individuals (60 loggerheads and 1 green) have been removed from the canal more 34

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

Of the 60 individual loggerheads known to have been caught more than once, 42 were caught twice, 9 were caught three times, 5 were caught four times, 2 were cap-tured six times, 1 was caught seven times and 1 was caught on nine separate oc-casions, yielding a total of 99 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).

However, the majority of recapture incidents involved juveniles (SLCL < 70 cm).

Recapture intervals for loggerheads ranged from four to 858 days, with a mean of 157 days (+174.0 days). The only green turtle caught more than once was captured on two occasions, returning to the canal 59 days after first being released into the ocean. About 56 percent of all loggerhead recapture incidents occurred within 90 days of previous capture and 89 percent within one year (Figure 22). The average interval between first and last capture was 262 days (+329.7 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 construction of power plant intake and discharge systems. Nesting returned to normal or above normal levels following both periods of construction. Power plant operation, exclusive of intake/discharge construction, has had no significant effect on nest densities.

There have been considerable year-to-year fluctuations in loggerhead nesting ac-tivity on Hutchinson Island from 1971 through 1990. Fluctuations are common at other rookeries and may result from overlapping of non-annual breeding populations.

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

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Since nesting surveys began in 1971, raccoon predation was considered the major cause of turtle nest destruction on Hutchinson Island. From 1971 through 1977, over-all predation rates in the nine survey areas were between 21 and 44 percent. However, a pronounced decrease in raccoon predation occurred after 1977, and overall preda-tion 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 1990, 132 green turtle and 12 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 1990, 112 loggerheads and 20 green turtles were removed from the St. Lucie Plant intake canal. Since monitoring began in May 1976, 1,843 loggerhead, 306 green, 9 leatherback, 8 hawksbill and 17 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 to natural variation in the occurrence of turtles in the vicinity of the offshore intake struc-tures, rather than to any influence of the plant itself.

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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 1990, 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 15 year monitoring period, 76 and 78 per-cent, respectively, of all loggerhead and green turtle captures have involved individuals in these categories; 16 percent of the loggerheads and 14 percent of the green turtles removed from the canal have been in fair or poor condition.

About nine percent of the turtles removed from the intake canal during 1990 had substantial injuries. However, most of these injuries were sustained prior to entrap-ment. Once in the canal, turtles confined east of A1A usually had very brief residency times and thus the relative condition of most turtles was not affected by their entrap-ment.

During 1990, one loggerhead and two green turtle mortalities occurred in the intake canal. These deaths probably resulted from drowning: two in ABI tangle nets, one at the UIDS barrier. Program modifications to permit continual surveillance of tangle nets 38

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during periods of deployment and improvements to the A1A barrier net were initiated to further reduce the potential for similar mortalities in the future.

Since intake canal monitoring began in 1976, 6.9 percent of the loggerheads and a similar percentage of green turtles removed from the canal were dead. The four Kemp's ridley mortalities in 1987 and 1988 were the only deaths recorded for this species since monitoring began. All of the leatherbacks and hawksbills entrapped in the intake canal at the St. Lucie Plant have been captured alive and released into the ocean. Modifica-tions to capture procedures, improvements to the A1A barrier net and virtual elimina-tion of low flow conditions in the canal has resulted in a 42 percent reduction in sea turtle mortality rates over the life of the canal capture program.

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

Lucie Plant, annual report 1976. Volumes I and II. AB-44. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Miami.

. 1978. Ecological monitoring at the Florida Power 8 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 8 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 8 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 8 Light Co., Miami.

. 1980b. Turtle entrainment deterrent study. AB-290. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Miami.

. 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.

. 1981b. Florida Power 8 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 8 Light Co., Miami.

. 1981 c. Proposed St. Lucie Plant preoperational and operational biological monitoring program - August 1981. AB-358. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Miami.

. 1982. Florida Power 8 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 8 Light Co., Miami.

. 1983. Florida Power 8 Light Company, St. Lucie Plant annual non-radiologi-cal aquatic monitoring report 1982. Volumes I and II. AB-442. Prepared by Applied Biol-ogy, Inc. for Florida Power 8 Light Co., Miami.

40

I I

I I

ABI (Applied Biology, Inc.). 1984a. Florida Power 8 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 8 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 8 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 8 Light Co., Juno Beach.

. 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 8 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 8 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.

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 eea turtle, Caretta caretta ~carett (L.), in America. Bulletin of the Florida State Museum, Biological Sciences, 4(10):319-348.

41

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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 aea turtle, Chelonia ~mdaa (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.

Caldwell, 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 caretta (L.), in America. Bulletin of the Florida State Museum, 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.

dt d AW tdtg 9 dt gtt I gt d tt IH tttllt ~ I,~WA I imbricata L., on Cousin Island, Seychelles. Biological Conservation 9:199-215.

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.

Ehrhart, L.M. 1980. Threatened and endangered species of the Kennedy Space Center:

marine turtle studies. In A continuation of baseline studies for environmentally monitor-ing space transportation systems (STS) at John F. Kennedy Space Center. Contract No. NAS-10-8986. Vol. IV, NASA Report 163122. September 1980.

42

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 ofsea turtles utilizing shallow coastal waters off Hutchinson Island, Florida. Pages 57-59 in Eckert, 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 Tortuguero, Costa Rica. Ecology 60(5):945-955.

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.

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.

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.I 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.

43

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I

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 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-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, compilers. Proceedings of the Ninth Annual Workshop on Sea Turtle Conservation and Biology. NOAA Technical Memorandum NMFS-SEFC-232.

Mendonca, M.T. and L.M. Ehrhart. 1982. Activity, population size and structure of the imma-ture Chelonia~mdas and Caretta caretta in Mosquito Lagoon, Florida. Copeia 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 turtle (Chelonia~mdas, loggerhead sea turtle (CGar tta~cretta and the Pacific Ridley tttid ptt ~li 3 d I 3 d 9 dgp I 9 t 11913.3 tt al Marine Fisheries Service, Dept. of Commerce, Washington, D.C.

I I

I I

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):773-780.

Owens, D.W., J.R. Hendrickson, V. Lance and I.P. Callard. 1978. A technique for determin-ing sex of immature Chelonia ~md~a 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. Manual 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:t97t-t984. 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.

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.

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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 1950:(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. Vl. Plankton dynamics, 1971-1973. Florida Marine Research Publications 34: 1-15.

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

Williams-Walls, N., J. O'ara, R.M. Gallagher, D.F. Worth, B.D. Peery and J.R. 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 (Chelonia ~mdas nesting in Florida. Pages 351-352 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.

Wi* II,WN.'l983.98 3 I Idi I pi Id I (Linnaeus, 1766). FAO Fisheries Synopsis, 137:1-78.

8 3 till ~ ~I ~Eh I 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.

46

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

Florida Marine Research Publications 18:1-17.

47

GULF OF MEXICO 0

0 YAROS KILOMETERS

~ ~

r SCALE St Lucia Plant Figure 1. Location of the St. Lucie Plant.

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350 300 250 z

0 200 D

z 150 100 50 1 2 3 4 5 6 7 8 9 NORTH POWER PLANT SOUTH Figure 4. Mean annual number of loggerhead turtle nests in each of the nine1.25-km-long survey areas, Hutchinson Island, 1971-1989, compared with number of nests during 1990. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1990 values (1980 data were excluded because not all areas were surveyed).

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z 100 50 A BCDE FGH I J K L MNOPQRS TUVWXYZABCDEFGH I J ABCDEFGH I J NORTH 1'OWER PLANT SOUTH Figure 5. Mean annual number of loggerhead turtle nests in each of the thirty-six 1-km-long survey areas, Hutchinson Island, 1981-1989, compared with number of nests during 1990. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1990 values.

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300 250 o o Area 4 (Power Plant Site) e ~ Area 5 (Control Site) 200 V)

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I 6000 5000 I-CD (D

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z 2000 1000 12000 CD O 10000 z

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31 30 O 29 28 5 27 26 Q.

25 24 23 22 21 20 120 90 (0

z 0 60 z

30 30 5 15 30 5 15 30 5 15 30 5 15 30 5 15 APR MAY JUN JUL AUG SEP Figure 10. Daily loggerhead turtle nesting activity and water temperature, Hutchinson Island, 1990.

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Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1990 values.

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~40 41-45 46-50 51-55 56-60 61-65 66-70 71-75 76-80 81-85 86-90 91-95 96- 101- 106- >110 STRAIGHT LINE CARAPACE LENGTH (cm) 100 105 110 Figure 15. Length distribution (SLCL) of loggerhead turtles (N=1,673) removed for the first time from the intake canal, St. Lucie Plant, 1976-1990.

No data collected for 81 individuals.

400 400 300 300 (0

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+10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101- 111- 121- 131- 141- i150

'I/EiGHT (kg) 110 120 130 140 150 Figure 1L Weight distribution of live loggerhead turtles (¹1,487) removed for the first time from the intake canal, St. Lucie Plant, 1976-1990.

No data collected for 267 individuals.

120 120 100 100 80 80 CO D

)00 60 60 0

K (9

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-15 16- 21- 26- 31- 36- 41- 46 56 66 76 86- 91- 96- 101- 106- > 110 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 STRAIGHT LINE CARAPACE LENGTH (cm)

Figure 17. Length distribution (SLCL) of green turtles (N=295) removed for the first time from the intake canal, St. Lucie Plant, 1976-1990.

No data collected for 10 individuals.

200 200 180 180 160 160 (D

140 140 D

9 D 120 120 z

0 100 100 80 80 z

60 60 40 40 20 20 1-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51- 101- 151- )200 WEIGHT (kg) 100 150 200 Figure 18. Weight distribution of green turtles (N=291) removed for the first time from the intake canal, St. Lucie Plant, 1976-1990.

No data collected for 14 individuals.

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60 MALES FEMALES 50 50 40 40 V)

D CI 0

30 30 0

K ILJ K

zD 20 20 10 10 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, 1977-1990 (N=255; sex not recorded for six individuals)85.0 cm).

50 ~

o e CANALCAPTURES o EMERGENCES 0 0 500

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/

/ / Z

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

100 100 JLJ CC I-CL O

CIJ 80 80 CJ CI Z

60 60 0

I-Z ILJ O

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ILJ 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-December, 1990 (N=90).

100 100

~ 80 80 (9

z I

f

/

t a- 60 60

/

I- /

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< 40 40 I

I ~ ~ Interval between successive captures I

20 I Interval between first and last capture 20 I

t 250 500 750 1000 1250 1750 RECAPTURE INTERVAL(days)

Figure 22. Cumulative percentage of all loggerhead recaptures occurring within various time intervals between successive captures (¹97j and first and last capture (¹58), St. Lucie Plant intake canal 1976-1990.

W 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 - 1990, COMPARED TO THE ACTUALNUMBER OF NESTS ON THE ISLAND, 1981 - 1990 Extrapolation from the Actual number Number of nests in the nine nine survey areas to the of nests on the i I 1971 1420 4203 1973 1260 3730 1975 1493 4419 1977 932 2759 1979 1449 4289 1981 1031 3052 3115 1982 4837 4690 1983 1592 4712 4743 1984 1439 4259 4277 1985 1623 4804 4877 1986 1839 5483 1987 1645 4869 4623 1988 1701 5035 1989 1774 5251 5193 1990 2177 6700

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TABLE 2 TOTAL NUMBER OF SEA TURTLE CAPTURES AND (NUMBER OF DEAD) TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976-1990 w ill Km'l 1976 ss(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 Mean's(4) 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) 112(1) 20(2) 1s2(s)

Total 1853(1 27) 306(21) 9(0) 8(0) 17(4) 2193(1 52)

Annual 130.0 21.9 0.6 0.6 1.2 154.3 Excludes 1976 (partial year of plant operation).

TABLE 3 TOTAL NUMBER OF (AND NUMBER OF DEAD) LOGGERHEAD TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976-1990 1976 2 0 7(1) 7 5(3) 9 33(4) 1977 13 s(1) 7 5(2) 1 5 15(1) 9(1) 5 5 80(5) 1978 19 11(2) 27(2) 19(5) 3(1) 10 12 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 0 7 8(3) 12 19 7 4 8 116(5) 1981 11(1) 11(3) 6 10 6 6 2(1) 0 0 3 62(5) 1982 6(2) 14 14 17(4) 7 2(1) 9(1) 9(5) 4(2) 1(1) 101(16) 4

& 1983 39 13(1) 0 4 7(1) s(2) 17 5 12 119(4) 1984 13 6 2(1) 7 28(1) 12(1) 26 16 10 9 8 148(3) 1985 15 20 13 16 17 20(3) 19(1) 14 7 3 2 157(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) 8(1) 24(3) 23(1) 26(1) 19(1) 17(1) 3 5 9 175(11) 1988 28 30 - 2 5 9 10(3) 11 13(2) 11(1) 134(6) 1989 4(2) 11 13 16 21(1) 15 3 5(1) 2 111(4) 1990 9 9 23 25 16 7(1) 4 1 3 112(1)

Total 219(11) 178(17) 152(9) 157(15) 162(6) 208(8) 172(11) 177(11) 126(12) 121 (13) 86(13) 95(1) 1853(127)

Monthly Mean 15.6 12.7 10.9 1 1.2 10.8 13.9 11.5 11.8 8.4 8.1 5.7 6.3

%Total Catch 11.8 9.6 8.2 8.5 8.7 11.2 9.3 9.6 6.8 6.5 4.6 5.1 eludes 1976 (partial year of plant operation).

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TABLE 4 TOTAL NUMBER OF (AND NUMBER OF DEAD) GREEN TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PIANT, 1976-1990 1976 0 0 0 0 1977 2 2(1) 0 1(1) 0 0 0 0 0 5(2) 1978 1 2 2 0 1(1) 0 0 0 0 6(1) 1979 0 1 0 1(1) 0 1 0 0 0 3(1) 1980 0, 5(1) 4(1) 0 0 1(1) 0 0 0 10(3) 1981 20(1) 7 1 1 0 2(1) 0 32(2) 1982 1 0 0 1 2 . 0 1983 8(1) 4 3(2) 4(1) 23(4) 1984 37(1) 10 4(1) 69(2) 1985 4 1 1 2 0 2 14 1986 1 1 6(1) 3 1 1 1 22(1) 1987 4 1 3 3 2 3 1 5 11 35 1988 12 11 4 2 3 6(2) 1 0 2 42(2) 1989 3(1) 0 6 3 1 1 0 0 2 17(1) 1990 6(1) 3(1) 3 1 1 1 0 2 1 20(2)

Total 99(5) 48(3) 33(4) 19(2) 9(1) 18(3) 8 9(1) 14 20(2) 24 306(21)

Monthly Mean 7.1 3.4 2.4 1.4 0.6 1.2 0.5 0.6 0.3 0.9 1.3 1.6

% Total Catch 32.4 15.7 10.8 6.2 2.9 5.9 2.6 2.9 1.6 4.6 6.5 7.8

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TABLE 5 NUMBER OF MONTHLYCAPTURES BY SIZE CLASS FOR LOGGERHEAD TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT, 1977-1990 Size classes SLCL in cm)

January 16 76 178 14.7 26 9.5 7 2 0 3.4 February 73 56 11.6 21 7.7 2 2 0 1.5 March 48 120 9.9 18 6.6 0 6 1 2.7 April 13 47 52 112 9.3 27 99 5 0 2.3 May 51 38 100 8.3 17 6.2 13 26 1 40 15.3 June 50 105 8.7 26 9.5 38 26 3 67 25.7

'2 July 35 81 6.7 28 10.3 21 29 4 20.7 August 42 48 97 8.0 35 12.8 19 18 1 38 14.6 September 4 48 38 7.4 16 5.9 5 8 2 15 5.7 October 8 35 32 75 6.2 2? 99 5 1 1 2.7 November 4 20 24 48 4.0 19 7.0 4 4 3.4 December 4 34 26 5.3 13 4.8 1 4 0 1.9 Total 101 592 517 1210 273 116 131 14 261

% of Total 69.4 15.7 15.0 Excludes 1976 (partial year of data).

No data were collected for 76 individuals.

TABLE 6 RELATIVE CONDITION OF SEA TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976- 1990 Relative 393 21.2 128 41.8 1 11.1 2 11.8 75.0 530 24.2 511 27.6 59 19.3 1 11.1 3 176 25.0 576 26.3 503 27.1 51 16.7 7 77.8 3 176 564 25.7 221 11.9 35 11.4 3 176 259 11.8 71 3.8 7 2.3 2 11.8 80 3.6 127 6.9 21 6.9 4 23.5 152 6.9 27 1.5 5 1.6 32 1.5 Total 1853 306 17 2193 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 otherwise condition not recorded.

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