ML17221A746

Annual Environ Rept (FPL-87) for 1987.

ML17221A746
Person / Time
Site:	Saint Lucie
Issue date:	12/31/1987
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17221A747	List: L-88-193, Forwards Annual Environ Rept for Apr 1988 & Annual Environ Operating Rept for 1987 ML17221A746 ML17221A749
References
NUDOCS 8805030185
Download: ML17221A746 (144)

Text

FLORIDA POWER 8 LIGHT COMPANY ST. LUCIE UNIT NO. 2 ANNUAL ENVIRONMENTAL REPORT (FPL-87)

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Page 1 of 4 ANNUAL ENVIRONMENTAL REPORT Introduction The St. Lucie Plant Unit 2 Environmental Protection Plan (EPP) requires the submittal of an annual report for various activities at the plant site including the reporting on sea turtle monitoring programs, and other matters related to Federal and State environmental permits and certifications. This report fulfills these reporting requirements.

II. Sea Turtle Monitoring and Associated Activities Aquatic and terrestrial sea turtle monitoring programs to satisfy Sections 4.2.1 (Beach Nesting Surveys), 4.2.3 (Studies to Evaluate and/or Mitigate Intake Canal Mortality) and 4.2.5 (Capture and Release Program) is concurrently submitted in a separate report (AB-595) prepared by Applied Biology, Inc.

Studies to evaluate and/or mitigate intake entrapment required by Section 4.2.2 of the EPP have been previously performed. A final report was submitted to the Office of Nuclear Reactor Regulation on April 18, 1985. With submittal of that report, the EPP requirement was fulfilled and will not be readdressed in this or future reports.

III Page 2 of 4 FPL will request modification of certain sections of the Environmental Protection Plan related to sea turtle programs, to reflect implementation and satisfaction of those requirements which have been completed as described above.

Requirements for reporting on the status of a light screen to minimize turtle disorientation as required by Section 4.2.4 of the EPP is ongoing. The Australian Pine light screen, located on the beach dune between the power plant and the ocean, is routinely surveyed to determine its overall vitality. The tree line is surveyed for any gaps occurring from tree mortality which would result in unacceptable light levels on the beach. Trees are replaced as necessary to maintain the integrity of the overall light screen.

III. Other Routine Reports The following items for which reporting is required are listed by section number from the Environmental Protection Plan (EPP):

5.4,.1(a) EPP NONCOMPLIANCES AND CORRECTIVE ACTIONS TAKEN No noncompliances under EPP Section 5.4.1(a) were determined to have occurred during 1987.

Page 3 of 4 5 4 1 (b ) STATION DESIGN AND OPERATION CHANGES g TESTS g AND EXPERIMENTS AFFECTING THE ENVIRONMENT No plant site activities were determined to be reportable under Section 5.4.1(b) during 1987.

5.4.1(c) NONROUTINE REPORTS SUBMITTED TO THE NRC FOR THE YEAR 1987 IN ACCORDANCE WITH EPP SUBSECTION 5.4.2:

1. Report concerning an overflow from the St. Lucie Unit 1 Sewage Treatment Plant reported to EPA on February 24, 1987 and the NRC on March 18, 1987.

2. Report concerning receipt of the final NPDES Permit for the St. Lucie Plant. (The State of Florida 401 Certification and the State of Florida Site Certification for St. Lucie Unit 2 are attachments to the NPDES Permit.) Permit effective date September 30, 1987.

The following reports were submitted to the NRC for informational purposes although not required under provisions of 5.4.2:

1. Report concerning an exceedance of the maximum temperature difference (dT) for the St. Lucie Units

Cl Page 4 of 4 1 and 2 once through cooling water system which was reported to the EPA on February 25, 1987 and to the NRC on March 18, 1987.

2. Sea turtle activities quarterly report dated April 2, 1987 for the first quarter 1987.

3. Sea turtle activities quarterly report dated July 8, 1987 for the second quarter 1987.

4. Sea turtle activities quarterly report dated October 6, 1987 for the third quarter 1987.

5. Sea turtle activities report dated January 5, 1988 for the fourth quarter 1987.

APPLIED BIOLOGY, INC. AB-595 FLORIDA POWER 8 LIGHT COMPANY ST. LUCIE UNIT 2 ANNUAL ENVIRONMENTALOPERATING REPORT 1987 0 2968 A NORTH DECATUR ROAD ~ ATLANTA, GEORGIA 30033 ~ 404-296-3900

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0 AB-595 FLORIDA POWER 5 LIGHT COMPANY ST. LUCIE UNIT 2 ANNUAL ENVIRONMENTAL OPERATING REPORT 1987 APRIL 1988 FLORIDA POWER 5 LIGHT COMPANY JUNO BEACH, FLORIDA APPLIED BIOLOGY, INC.

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ENVIRONMENTAL OPERATING REPORT TABLE OF CONTENTS

~Pa e TABLE OF CONVERSION FACTORS FOR METRIC UNITS EXECUTIVE

SUMMARY

1v Introduction 1v Turtle Nesting Survey 1V Intake Canal Monitoring- v Other Related Activities v INTRODUCTION-

Background

Area Description--

Plant Description TURTLES Introduction I Materials and Methods- 11 Nesting Survey ll Intake Canal Monitoring 13 Studies to Evaluate and/or Mitigate Intake Entrapment --- 16 Light Screen to Minimize Turtle Disorientation ---------- 16 Results and Discussion 16 Nesting Survey 16 Distribution of Loggerhead Nests Along Hutchinson Island 16 Number of Nests and Loggerhead Population Estimates - - 23 Temporal Loggerhead Nesting Patterns 25 Predation on Loggerhead Turtle Nests 26 Green and Leatherback Turtle Nesting 27 Intake Canal Monitoring 29 Species Number and Temporal Distribution- 30 Size-Class Distributions- 32 Sex Ratios- 34 Capture Efficiencies 36 Relative Condition 38 Mortal i ti es 42 Recapture Inci dents 46 Summary- 47 LITERATURE CITED 52 FIGURES 59 TABLES- 81 11

TABLE OF CONVERSION FACTORS FOR METRIC UNITS To convert Multiply by To obtain

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centigrade (degrees) (Cx 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 x 10 feet per second cubic centimeters (cm3) 1.0 x 10 liters grams (g) 2.205 x 10 pounds grams (g) 3.527 x 10" ounces (avoi rdupois) hectares (ha) 2.471 acres kilograms (kg) 1.0 x 103 grams kilograms (kg) 2.2046 pounds kilograms (kg) 3.5274 x 101 ounces (avoirdupois) kilometers (km) 6.214 x 10-1 miles (statute) kilometers (km) 1.0 x 106 mi 1 1 imeters liters (1) 1.0 x 10 cubic centimeters (cm3) liters (1) 2.642 x 10 gallons (U.S. liquid) meters (m) 3.281 feet meters (m) 3.937 x 10 inches meters (m) l. 094 yards microns (9) 1.0 x 10 6 meters milligrams (mg) 1.0 x 10"3 grams mi lligrams/liter (mg/1) 1.0 parts per mi1 1 i on milliliters (ml) 1.0 x 10 liters (U.S. liquid) millimeters (mm) 3.937 x 10"2 inches millimeters (mm) 3.281 x 10 feet square centimeters (cm2) 1.550 x 10 square inches square meters (m2) 1.076 x 10 square feet square mil limeters (mm2) 1.55 x 10 square inches

EXECUTIVE

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 8 Envi ronmental Protect ion Plan (EPP) to St. Luc i e Unit 2 Faci l i ty Operating License No. NPF-16. This report discusses environmental pr o-tection activities related to sea turtles as required by Subsection 4.2 of the EPP.

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

Low nesting activity in 1975 and 1981 - 1983 in the vicinity of the power plant was attributed to construction of plant intake and discharge struc-tures. Nesting returned to normal or above normal levels following both periods of construction. Power plant operation exclusive of construction has had no significant effect on nesting near the plant. Data collected through 1987 have shown no long-term reductions in total nesting, total emergences or nesting success on the island. Formal requirements to con-duct this program expired in 1986 but were voluntarily continued in 1987 with agreement from federal and state agencies.

0 INTAKE CANAL MONITORING Since plant operation began in 1976, 1,748 sea turtles (including 79 recaptures) representing five different species have been removed from the intake canal . Eighty-six percent of these were l oggerheads.

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

Turtles confined between the A1A barrier net and intake headwalls usually resided in the canal for a relatively short period of time, and most were in good to excellent condition when caught. Drowning was thought to be responsible for most recent canal mortalities and appropriate measures, including the installation of a new barrier net, were taken to mi nimize future mortal i ti es.

OTHER RELATED ACTIVITIES The integrity of a vegetative light screen along the dune line at the St. Lucie Plant is assessed on a continuing basis. During 1987, routine inspections of the screen were made and replantings conducted as needed.

Studies to evaluate various intake deter rent 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 con-tained in the United States Nuclear Regulatory Commission's (NRC)

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

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

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

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

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

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

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

The results of Unit 1 operational and Unit 2 preoperational biotic moni-toring at the St. ~Lucie Plant were presented in six annual reports (ABI, 1977, 1978, 1979, 1980a, 1981b, 1982) . In January 1982, a National Pollutant Discharge Elimination System (NPDES) permit was issued to FPL by the U.S. Environmental Protection Agency (EPA). The EPA guidelines for the St. Lucie site biological studies were based on the document entitled "Proposed St. Lucie Plant Preoperational and Operational Biological Monitoring Program - August 1981" (ABI, 198lc). Findings from these studies were reported in three annual reports (ABI, 1983, 1984a, 1985a). The EPA biotic monitoring requirements were deleted from the NPDES permit in 1985.

Jurisdiction for sea turtle studies is with the NRC, which is con-sidered to be the lead federal agency relative to consultation under the Endangered Species Act. Previous results dealing exclusively with sea turtl e studi es are contained in four envi ronmental operating reports (ABI, 1984b, 1985b, 1986, 1987). This report describes the 1987 environ-mental protection act ivi ties related to sea turtl es, as requi red 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 I and 2). The plant is approximately midway between the Ft. Pierce and St. Lucie Inlets. It is bounded on its east side by the Atlantic Ocean and on its west side by the Indian River Lagoon.

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

Island vegetation is typical of southeastern Florida coastal areas; dense stands of Australian pine, palmetto, sea grape and Spanish bayonet are present at the higher elevations, and mangroves abound at the lower ele-vations. Large stands of black mangroves, including some on the plant s i te, have been ki 1 1 ed by fl oodi ng for mos qui to control ove r past decades.

The Atlantic shoreline of Hutchinson Island is composed of sand and shell hash with intermittent rocky promontories protruding through the beach face along the southern end of the island. Submerged coquinoid rock formations parallel much of the island off the ocean beaches. The ocean bottom immediately offshore from the plant site consists primarily of sand and shel 1 sediments. The unstable substrate limi ts the establi shment 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-HW 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 mi nimize fish entrainment. Horizontal intake velocities are less than 30 cm/sec. From the intake structures, tlie 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 1500-m long intake canal. This canal transports the water to the plant. After passing through the plant, the heated water is discharged into a 670-m long canal that leads to two buried discharge pipeli nes. These pass underneath the dunes and beach and along the ocean floor to the submerged discharges, the first of which is approximately 365 m offshore and 730 m north of the intake.

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

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

TURTLES The NRC's St. Luci e Unit 2 Appendix B Envi ronmental 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, 1982j and in the Endangered Species Biological Assessment (March 1982) [Bellmund et al., 1982] will be addressed by programs as follows:

4.2. 1 Beach Nestin Surve s Beach nesting surveys for all species of sea turtles will be conducted on a yearly basis for the period of 1982 through 1986. These surveys will be con-ducted during the nesting season from approximately mid-April through August.

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

The entire beach will be surveyed seven days a week.

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

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

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

The study will determine with laboratory and field experiments if sound and/or light will result in a

'reduction of total turtle entrapment rate.

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

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

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

If an 80 percent reduction of turtle entrapment can-not be projected to all three intake structures, then an interagency task force composed of HRC, 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 bar rier, emergence of new technology or methods to deter turtles).

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

4.2.4 Li ht Screen to Minimize Turtle Disorienta-tion [N  : 1s 1s a so Section 4.2 o the NRC St.

Luci e Unit 1 Appendix B Technical Specifications issued May 1982]

Australian pine " or other suitable plants (i.e.,

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

4.2.5 Ca ture and Release Pro ram Sea turtle removal from the intake canal will be conducted on a continuing basis. The turtles wi 11 be captured with large mesh nets, or other suitable nondestructive device(s), if deemed appropriate. A formalized daily inspection, from the shoreline, of the capture device(s) will be made by a qualified individual when the device(s) are deployed. The turtles will be identified to species, measured, weighed (if appropriate), tagged and released back into the ocean. Records of wounds, fresh or old, and a subjective judgement on the condition of the turtle (e.g., barnacle coverage, underweight) wi 11 be maintained. Methods of obtaining additional biological/physiological data, such as blood analy-ses and parasite loads, from captured sea turtles will be pursued. Dead sea turtles will be subjected to a gross necropsy, if found in fresh condition.

INTRODUCTION Hutchinson Island, Florida, is an important rookery for the loggerhead turtle, Caretta caretta, and also supports some nesting of the Ch1 l ~, d h 1 h k coriacea (Caldwell et al., 1959; Routa, 1968; Gallagher et al., 1972; Worth and Smith, 1976; Williams-Walls et al., 1983). All three species are protected by state and federal statutes. The feder al government classifies the loggerhead turtle as a threatened species. The leather-back 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.

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

Daytime surveys to quantify nesting, as well as nighttime turtle tagging programs, were conducted in odd numbered years from 1971 through 1979. During daytime nesting surveys, nine 1.25-km-long survey areas were monitored five days per week (Figure 3). The St. Luci e Plant began operation in 1976; therefore, the first three survey years (1971, 1973 and 1975) were preoperational. Though the power plant was not operating during 1975, St. Lucie Plant Unit No. 1 ocean intake and discharge struc-tures were installed during that year. Installation of these structures included construction activities conducted offshore from and perpen-dicular to the beach. Construction had been completed and the plant was in full operation during the 1977 and 1979 surveys.

A modified daytime nesting survey was conducted in 1980 during the preliminary construction of the ocean discharge structure for St. Lucie Plant Unit 2. During this study, four of the previ ously 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 1987, thirty-six 1-km-long survey areas comprising the entire island were monitored seven days a week during the nesting season (Figure 3). The St. Lucie Plant Unit 2 discharge struc-

ture was installed during the 1981 nesting season. Offshore and beach construction of the Unit 2 intake structure proceeded throughout the 1982 nesting season and was completed near the end of the 1983 season.

Construction activi ties associated with installation of both structures were similar to those conducted when Unit 1 i ntake and discharge struc-tures 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 Protection Plan was completed with submission of the 1986 nesting survey data (ABI, 1987). The nesting survey was continued volun-tarily in 1987 with agreement from federal and state agencies. Results are presented in this report and discussed in relation to previous fin-dings.

In addition to monitoring sea turtle nesting activities and relo-cating nests away from plant construction areas, monitoring of turtles in the intake canal has been an integral part of the St. Lucie Plant envi ronmental moni to ri ng program. Turtl es enteri ng the ocean intake structures are rapidly transported with cooling water through the intake pipes and into the enclosed canal system where they are entrapped. Since the plant became operational in 1976, turtles entrapped in the intake canal have been captured, measured, tagged and returned alive to the ocean.

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Previous publications and technical reports have presented findings of the nesting surveys, nest relocation activi ties and canal capture program (Gallagher et al., 1972; Worth and Smith, 1976; ABI, 1978, 1980a, 1981a, 1982, 1983, 1984b, 1985b, 1986, 1987; Williams-Walls et al., 1983; Proffitt et al., 1986; Ernest et al., in press; Martin et al., in press).

Results of studi es to assess the ef fects of thermal di scharges on hatchling swimming speed have also been reported (ABI, 1978; O'ara, 1980). The purpose of this report is to 1) present 1987 sea turtle nesting survey data and summarize observed spatial and temporal nesting patterns since 1971, 2) document and summarize predation on turtle nests since 1971, and 3) present 1987 canal capture data and summarize related data collected since 1976.

MATERIALS AND 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, 198la, 1982, 1987). Methods .used during the 1987 survey were designed to allow comparisons with these previous stu-dies.

From 16 April through 29 April 1987, eight preliminary nest surveys were conducted along Hutchinson Island from the Ft. Pierce Inlet south to the St. Luci e Inl et. After 29 April, surveys were conducted daily through 11 September. Several additional surveys were conducted after 11 September to confirm that nesting had ceased, the last survey being con-

ducted on 18 September. Biologists used small off-road motorcycles to survey the island each morning. New nests, non-nesting emergences (false crawls), and nests destroyed by predators were recorded for each of the thirty-six 1-km-long survey areas comprising the entire island (Figure 3). The nine 1.25-km-long survey areas established by Gallagher et al.

( 1972) also were monitored so 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 thi rty-six 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 charac-teristics (packed sand, scattered rock, vegetation on the beach, exposed roots on the primary dune, etc.).

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

Additionally, data from stranded turtles found during beach surveys were routinely provided to the National Marine Fisheries Service through the Sea Turtle Stranding and Salvage Network.

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Intake Canal Monitorin Routine capture of sea turtles from the St. Luci e Plant intake canal continued during 1987. Turtles were removed from the canal with large-mesh tangle nets fished between the intake headwalls and a barrier net located at the Highway A1A bridge (Figure 2). These nets were usually deployed on Monday morning and retrieved on Friday afternoon. To detect captures, formal daily inspections of the nets (mornings and afternoons) were made each day of deployment.

Various sizes, numbers and locations of tangle nets have been used to date as capture techniques have been refined. Nets in recent use were from 32 to 61 m in length, 2.7 to 3.7 m in depth and 30 to 40 cm in stretch mesh. Large floats kept the nets at the surface, and because nets were not weighted with lead lines, turtles which became entangled remained at the water's surface until removed.

The barrier net at the A1A bridge is intended to confine turtles to the easternmost section of the intake canal, where capture techniques have been most effective. However, the integrity of the barrier net occasionally has been compromised, and turtles have been able to swim over or under it. Prior to December 1986, most turtles circumventing the barrier net eventually emerged in the intake wells of Units 1 and 2 (Figure 2), where they were retrieved by means of large mechanical rakes or specially designed nets. However, during 1986, a security intrusion barrier was constructed across the north-south arm of the intake canal.

After its emplacement, turtles larger than 30.5 cm in carapace width were 13

impeded from reaching the intake wells by a large-mesh chain net. Tangle nets were set west of the A1A barrier net to capture these turtles.

Turtles smaller than 30.5 cm can pass through the mesh of both the barrier net and the intrusion barrier.

Personnel of Applied Biology, Inc. were on call 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day to retrieve captured turtles from both the intake wells and turtle nets.

The utmost care was taken in handling captured turtles to prevent injury or trauma.

After removal from the canal, turtles were identified to species, measured, weighed, tagged, examined for overall condition (wounds, abnor-mali ties, parasites, etc. ) and released back into the ocean. Although both straight-li ne and curved carapace lengths were measured, only straight-line measurements were used in analyses presented in this report. Straight-line carapace length (SLCL) was measured from the pre-central scute to the notch between the postcentral scutes (mi nimum cara-pace length of Pritchard et al., 1983).

Since 1982, blood samples have been collected and analyzed to i nvestigate the potential occurrence and significance of anemia in cap-tured animals and to determine the sex of immature turtles. Blood was removed from the paired dorsal cervical sinuses of subject turtles using the technique described by Owens and Ruiz (1980). A small subsample of whole blood was hemolyzed and hemoglobin measured in grams per 100 ml by colorimetry using an A.O.

~ ~ 10100 hemoglobinometer. The remainder of the

l li

blood sample was centrifuged for 15 minutes to separate cells and serum.

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

1978). During 1984 and 1985, blood cell samples were also provided to the National Marine Fisheries Service for the purpose of developing and refining methods for use in conducting turtle stock analysis.

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

Resuscitation techniques were used if a turtle was found that appeared to have died recently. Beginning in 1982, necropsies were conducted on dead turtles found in fresh condition; two individuals, one Kemp's ridley and one loggerhead, were found suitable for necropsy in 1987.

Florida Power 5 Light Company and Applied Biology, Inc. continued to assist other sea turtle researchers in 1987. In addition to the Florida DNR's Headstart Program, data, specimens and/or assistance have been given to the National Marine Fisheries Services, U.S. Army Corps of Engineers, Smithsonian Institution, South Carolina Wildlife and Marine Resources Di vi si on, Center for Sea Turtl e Research (Uni vers i ty of Florida), Texas A & M University, University of Rhode Island, University of South Carolina, University of Illinois, University of Georgia and the Western Atlantic Tur tie Symposium.

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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 ll April 1984. Requirement 4.2.2 of the NRC's St. Lucie Unit 2 Appendix B Environmental Protection Plan is considered completed with submission of deterrent study findings.

Li ht Screen to Minimize Turtle Disorientation A vegetative beach dune light screen created to minimize turtle disorientation at the St. Lucie Plant

~ was routinely inspected by FPL per-sonnel during 1987. ~ Replantings were conducted as required to maintain its integrity.

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 acti-vity 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 considerable annual variation within individual survey areas (Figures 4 and 5). Yet, the annual spatial distribution of those nests among survey areas has pro-16

duced a r ather 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 curvilinear when all 36 1-km-long survey areas are included in the analy-sis (Figure 5). During 1987 the distribution of loggerhead nests along the island followed the same general pattern as previously reported, nest densities increasing abruptly from north to south along the northern por-tion of the island, reaching maximum densities in central survey areas and then decreasing slightly toward the southern portion 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 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 1

by loggerhead turtles, other factors must also contribute to the selec-tion 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 fac-tors affecting 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 17

patterns and speci fic envi ronmental conditions are often di fficul t to establish because of the interrelationship of the factors involved and may be obscured by nest site tenacity. Schulz ( 1975) suggested that nest site tenacity may force adult females to maintain their nesting site as long as possible, even though those sites may be undergoing environmental changes.

Not all ventur es onto the beach by a female turtle culminate in suc-cessful 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 disturbances or unsatisfac-tory nesting beach characteristics. Therefore, certain factors may affect a turtle's preference to emerge on a beach, while other factors may affect a turtle's tendency to nest after it has emerged. An index which relates the number of nests 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 success" and is defined as the percentage of total emergences that result in nests.

Historically, the pattern of loggerhead emergences on the island has paralleled the di stribution of nests (ABI, 1987), and this same trend was apparent in 1987 (Figure 6). In contrast, nesting success by loggerheads along the island has typically lacked gradients (Figure 7). Thus, the 18

0 relatively high numbers of loggerhead nests usually observed along the southern half of the island have resulted primarily from more turtles coming ashore in that area rather than from more preferable nesting con-ditions being encountered by the turtles after they emerged.

Hughes (1974) and Bustard (1968) found that loggerheads preferred beaches adjacent to outcrops of rocks or subtidal reefs. Williams-Walls et al. (1983) suggested that the nesting gradient on Hutchinson Island may be influenced by the offshore reefs if female turtles concentrate on the reef s cl osest to the beach to rest or feed. The proximi ty of offshore reefs would put the greatest concentration of turtles near the southern half of the island where coincidentally nesting is highest.

Loggerhead nesting densities during 1987 were generally within the r ange of values previ ously recorded (Figures 4 and 5) . Two notable exceptions include record low nesting in Area F and record high nesting in Area JJ. Low nesting in Area F was apparently due to pre-emergent as well as post-emergent factors since both the number of emergences and nesting success were low during 1987 (Figures 6 and 7). The removal of considerable beachfront vegetation in Area F between the 1986 and 1987 nesting seasons offers one explanation. Baldwin and Lofton (1959) indi-cated that nesting turtles show a preference for beaches backed by high dunes or vegetation and a hesitancy to emerge on barren beaches.

Another explanation involves the use of the beach at night by off road vehicles. Although illegal, vehicular traffic on the beach in Area 19

F was considerable during 1987. Turtles are very sensitive to alarming stimuli both prior to emerging onto a beach (Schulz, 1975) and during their ascent of the beach (Hi rth, 1971). Among these alarming stimuli, movi ng lights will frighten nesting sea turtles of all species (Mortimer, 1982). Lights associated with vehicles on the beach may have contributed to decreases in both the number of emergences and nesting success.

Record high loggerhead nesting in Area JJ during 1987 (Figure 5) may be attributable to unfavorable nesting conditions on the adjacent northern section of beach. Sandbags installed in Area II between the 1986 and 1987 nesting seasons were apparently responsible for a high number of false crawls which accounted for the record low nesting success observed in that area during 1987 (Figure 7). The high number of emergences in Area II (Figure 6) probably reflects repeated unsuccessful nesting attempts by individual turtles. Many of these turtles probably reemerged in Area JJ where, because of more favorable beach conditions, they nested.

In 1987 as in previ ous years, loggerhead emergences were least numerous in Area A and .increased steadily in a southerly direction to about Area K (Figure 6). The presence of deep water close to shore has been suggested as a factor which might influence sea turtles to emerge on particular beaches (Hendrickson and Balasingam, 1966; Mortimer, 1982).

The distance from shore to the thirty-foot water depth contour decreases continuously from Area A through Area F, and this may partially account for the observed pattern of increased emergences from north to south 20

al ong the north end of the i sl and. Furthermore, 1 arge publ i c beach accesses in Areas A through C, combined with considerable artificial lighting in those areas, provide the potential for extensive and highly visible human activity on the beach at night. As previously stated, turtles are very sensitive to alarming stimuli just prior to and duri ng emergences onto beaches. Nighttime human activity in these areas may deter turtles from emerging or from nesting after they emerge onto the beach, and may have contributed to the somewhat lower nesting success observed there (Figure 7). Historically, low nesting success in the northernmost areas has been attributed to beach characteristics such as persistent and extensive areas of vertical relief (benches), accumula-tions of rocks and shells, and compact sand. Apparently, a combination of factors affecting both emergence and nesting success has been respon-sible for the extremely low nest densities usually observed along that part of the island.

Numbers of loggerhead emergences and consequently nest densities have remained relatively low in Area Z from 1981 through 1987 (Figures 5 and 6). Since this area includes a large public beach access, a motel and considerable artificial lighting, nighttime human activity may deter turtles from coming ashore.

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 analyses, using log-likelihood tests of independence (G-test; Sokal and Rohlf, 1981) 21

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 1 evel s simi1 ar to or greater than those at a control site in years fol 1 owi ng construct ion (Fi gure 8) .

The G-test was also used to assess the impacts of power plant opera-t i on, exclusive of construct i on (AB I, 1987) . Thi s test indi cated a significant difference in the relative proportion of nests between the plant site (Area 4) and a comparable control site (Area 5) when baseline years (1971 and 1973) and operational years without construction were compared. However, this di fference resulted from a di sproportionately high number of nests in Area 4 during a single year (1986) rather than from any long-term decline in nesting resulting from power plant opera-tion. When data from 1986 were excluded, no significant difference be-tween baseline and operational periods 'ere detected. The same results were obtained when 1987 data were included in the analyses.

Data collected through 1987 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).-

22

Number of Nests and Lo erhead Po ulation Estimates Various methods were used during surveys prior to 1981 to estimate the total number of loggerhead nests on Hutchinson Island based on the number of nests found in the nine 1.25-km-long survey areas (Gallagher et al., 1972; Worth and Smith, 1976; ABI, 1980a). Each of these methods were subsequently found to consistently overestimate island totals (ABI, 1987). Since whole-island surveys began in 1981, it has been possible to determine the actual proportion of'otal 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 1987 the total number of nests in the nine areas varied from 33.1 to 35.6 percent of the total number of nests on the island (Table 1). This is slightly higher than the 31.3 percent which would be expected based strictly on the proportion of linear coastline comprised by the nine areas. Using the seven-year mean of 33.9 percent, estimates of the total number of nests on Hutchinson Island can be calcu-lated by multiplying the number of nests in the nine areas by 2.95. This technique, when applied to the nine survey areas during the seven years in which the entire 'island was surveyed, produced whole-island estimates within five percent of the actual number of nests counted. Because the proportion of nests recorded in the nine survey areas remained relatively constant over the last seven years, this extrapolation procedure should provide a fairly accurate estimate of total loggerhead nesting for years prior to 1981.

23

It is clear that loggerhead nesting activity on Hutchinson Island fluctuates considerably from year to year (Table 1); Annual variations in nest densities also are common at other rookeries (Hughes, 1976; Davis and Whiting, 1977; Ehrhart, 1980) and may result from the overlapping of non-annual breeding populations. During the last six ye'ars, however, annual nest production has remained relatively high. Total nesting acti-vity was greatest during 1986 when 5,483 loggerhead nests were recorded on the island. During 1987, 4,623 nests were counted. No relationships between total nesting activity and power plant operation or intake/di s-charge construction were indicated by year-to-year variations in total nesting on Hutchinson Island.

In order to determine the total number of female loggerhead turtles nesting on Hutchinson Island during a given season, an estimate of the number of nests produced by each female must be determined. A comparison of the number of nests produced by tagged turtles during the 1975, 1977 and 1979 surveys indicated that an average of two nests per female was t

produced during a nesting season (ABI, 1980a).. Thus, estimates of the total numbers of femal es nesting during previ ous survey years may be obtained by dividing the calculated total number of nests by two. Based on extrapolation estimates of total nesting, the number of femal e loggerhead turtles nesting on Hutchinson Island varied from approximately 1,400 to 2,200 individuals during survey years 1971 through 1979. Using whole-island nest counts, the estimated total number of nesting females varied from 1,558 to 2,742 individuals between 1981 and 1987.

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Tem oral Lo erhead Nestin Patterns The loggerhead turtle nesting season usually begins in early May, when ocean temperatures reach 23'o 24'C, attains a maximum during June or July, and ends by late August or early September (ABI, 1987). Nesting activity during 1987 followed this same pattern (Figure 10). Shifts in the temporal nesting pattern on Hutchinson Island .may be influenced by fluctuations in wa'ter temperature. This was observed during 1975 and 1982 when early nesting in April coincided with average ocean tem-peratures above 24"C (ABI, 1983; Williams-Walls et al., 1983).

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), Wil 1 iams-Walls et al. (1983) and ABI (1982, 1983, 1984b, 1985b, 1986, 1987) suggested that these intrusions may have been responsible for the temporary declines in loggerhead turtle nesting activity previously observed on Hutchinson Island. Considerable decreases in ocean temperatures were recorded at the St. Lucie Plant during June and early August 1987 (Figure 10). A substantial decrease in nesting on the island corresponded with the latter of these cool water intrusions.

To determine if plant operation has affected the timing of nesting activity, seasonal nesting patterns (nest density on a month-to-month basis) for Area 4 (plant site) and Area 5 (control site) were compared statistically during each study year (Kolmogorov-Smi rnov test; Sokal and Rohlf, 1981). ~ No significant (P<0.05) differences

~ were detected between 25

areas during any study year, either before or after the power plant began operating. The results of these analyses indicate that plant operation has not significantly affected temporal nesting patterns adjacent to the plant.

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 predation of loggerhead turtle nests on Hutchinson Island has not approached this level during any study year, though levels for individual 1.25-km-long areas have been as high as 80 percent (Figure 11). Overall predation rates for- survey years 1971 through 1977 were between 21 and 44 percent, with the 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 1987, seven percent (304) of the loggerhead nests (n=4,623) on the island were depredated by raccoons. As in previous years (ABI, 1987), predation of tur tie nests was primarily restricted to the most undeveloped portion of the island (i.e., Areas f through U) and the southernmost areas (Areas II and JJ; Figure 12).

26

Ghost crabs have been reported by numerous researchers as important predators of sea turtle nests (Baldwin and Lofton, 1959; Schulz, 1975; Di amond, 1976; Fowl er, 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. guantification of ghost crab predation was initiated the same year.

Overall predation rates by ghost crabs have varied from 0.3 to 2. 1 percent during the last five years (ABI, 1987). During 1987, 0.3 percent

( 15) of the loggerhead nests (n=4,623) on the island were destroyed by ghost crabs (Figure 12). 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 pre-dations, the overall predation rates by ghost crabs range from 1.5 to 3.2 percent. During 1987, 1.5 percent (71 nests) were destroyed by either ghost crabs or a combination 'of ghost crabs and raccoons.

Green and Leatherback Turtle Nestin Green and, leatherback turtles also nest on Hutchinson Island, but in fewer numbers than loggerhead turtles. Prior to 1981, both survey (nine 1.25-km-long sections) and inter-survey areas were monitored for the pre-sence of green and leatherback nests. Thirty-one kilometers of beach from Area 1 south to the St. Lucie inlet were included in that effort.

During whole isl and surveys from 1981 through 1987, only two of 101 leatherback nests and only four of 350 green nests were recorded on the 27

five kilometers of beach north of Area 1. Therefore, previous counts of green and leatherback nests within the 31 kilometers surveyed were pro-bably not appreciably di fferent from total densities for the entire island. Based on this assumption, green and leatherback nest densities may be compared among all survey years, except 1980, when less than 15 kilometers of beach were surveyed.

Prior to 1987, the number of nests observed on the island ranged from 5 to 68 for green turtles and from 1 to 20 for leatherbacks (Figure 13). During the 1987 survey, 72 green turtle and 18 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 1987, green turtles .nested from 15 June through 9 September.

Leatherback turtles usually nest on the island from mid-April through early to mid-July. During 1987 this species nested from 3 May through 20 July.

Considerable fluctuations in green turtle nesting on the island have occurred among survey years (Figure 13). This is not unusual since there are drastic year-to-year fluctuations in the numbers of green turtles nesting at other breeding grounds (Carr et al., 1982). Despite these fluctuations, green turtle nesting has remained relatively high during the last six years (1982 through 1987) and may reflect an increase in the 28

number of nesting females in the Hutchinson Island area. During 1987, green turtles nested most frequently along the southern half of the island. This is consistent with results of previous surveys.

Leatherback turtle nest densities have remained low on Hutchinson Island; however, densities during the last eight survey years have been higher than during the first four survey years (Figure 13). This may reflect an overall increase in the number of nesting females in the Hutchinson Island area. During 1987, leatherback turtles primarily nested on the southern half of the island between Areas BB and GG (Figure 3).

Intake Canal Monitorin Entrainment of sea turtles at the St. Lucie Plant has been attri-buted to the presumed physical attractiveness of the offshore structures housing the intake pipes rather than to plant operating characteristics (ABI, 1980b and 1986). Even when both units are operating at full capa-city, turtles must actively swim into one of the intake pipes before they encounter current velocities sufficiently strong to effect entrainment.

Consequently, a turtle's entrapment relates primarily to the probability that it will detect and subsequently enter one of the intake structures.

Assuming that detection distances do not vary appreciably over time and that all turtles (or a constant proportion) are equally attracted to the structures, capture rates will vary proportionately 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 population being sampled.

29

S ecies Number and Tem oral Distribution During 1987, 218 sea turtle captures took place in the intake canal of the St. Lucie Plant (Table 2). Four of the five species of sea turtles occurring in coastal waters of the southeastern United States were represented in the catches, including 175 loggerheads, 35 greens, 2 hawksbills and 6 Kemp's ridleys. Since intake canal monitoring began in Hay 1976, 1,497 loggerhead (including 79 recaptures), 227 green (including 1 recapture), 8 leatherback, 6 hawksbill and 10 Kemp's ridley captures have been reported from the St. Luci e Plant.

Annual catches of loggerheads increased steadily from a low of 33 in 1976 (partial year of plant operation and monitoring) to 173 in 1979 (Figure 14). ~ After declining

~

between 1979 and 1981, yearly catches of 1 oggerheads again rose steadily, reaching a high of 195 during 1986.

Captures in 1987 were down slightly from 1986.

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 probabi 1-i ty of a turtle being entrained. Because this change cannot be quan-tified, data collected prior to 1982 may not be comparable with that collected after 1983. Nevertheless, the general rise in canal captures since 1981, even after the third structure was completed, suggests a genuine, long-term increase in the number of turtles occurring near the plant.

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i During 1987, the monthly catch of 1 og ge rheads ranged from 3 (October) to 26 (January and June), with a monthly mean of 14.6 (+8.9; Table 3). Captures during April, May and June were much higher than historical averages for those months, while captures during September and October were much lower than average (Figure 15). Over the entire moni-toring 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 (1977-1987) were com-b i ned, the j ri ty ma o of 1 og gerheads were captured in January (13. 2 percent); fewest captures occurred during 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 1987, 35 individuals were captured. The average annual catch of green turtles, excluding 1976, was 20.6 (+19.4). No consistent trends in annual catches are evident from the data (Figure 14).

Green, turtles have been caught during every month of the year, with average monthly catches for all years combined ranging from 0.3 in May to

7. 1 in January (Table 4). However, seasonal abundance patterns of greens are much more pronounced than for loggerheads, nearly 75 percent of all captures occurring between November and March. During 1987, the largest

. 31

0 number of greens (11) were captured in December. 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 eleven year study period (Table 2). Each species has shown rather pronounced seasonal occurrences; all but one of the eight leatherbacks were collected between February and May, five of the six hawksbills were collected between June and September, and all but one of the 10 Kemp's ridleys were caught between

~

December and April.

Size-Class Distributions To date, live loggerheads removed from the intake canal have r anged in length (SLCL) from 40.4 to 112.0 cm (x = 65.2 + 12.3 cm) and in weight from 10.9 kg to 154.7 kg (Figures 16 and 17). About 75 percent of all live loggerheads captured were 70 cm or less in length and weighed less than 100 pounds.

A carapace length of 70 cm approximates the smallest size of nesting loggerhead females observed along the Atlantic east coast (Hi rth, 1980).

However, adults can only be reliably sexed on external morphological characteristics (e.g., relative tail length) after obtaining a length of about 80 cm. Based on these di vi sions, data were segregated into three groups: juvenile/sub-adults (<70 cm; the demarcation between these two components is not well established in the literature), adults (>80 cm) and transitional (70-80 cm). The latter group probably includes some 32

J I

L

mature and some immature individuals. Of the 1,348 captures for which 1 ength data were collected, 75 percent were juveni1 es/sub-adul ts, the majority of these measuring between 50 and 70 cm SLCL (Table 5). The remaining 25 percent was divided nearly equally between adults and indi-viduals in the transitional size class. Similar size-frequency di stribu-tions, indicating a preponderance of juveniles, have been reported for the Mosquito/Indi an River Lagoon (Mendonca and Ehrhart, 1982), the Canaveral ship channel (Ogren and McVea, 1982), Georgia and South Carolina (Hi 1 lestad et al., 1982) and suggest that coastal waters of the southeastern United States constitute an important developmental habitat for Caretta caretta.

Seasonal patterns of abundance for various size classes indicated that juveniles and sub-adult loggerheads were slightly more abundant during the winter than at other times of the year (Table 5). About 37 percent of juvenile/sub-adult loggerheads were captured between January and March, the remainder being rather evenly distributed among other months. The seasonal distribution of adult. loggerheads was much more pronounced, 60 percent of all captures occurring between June and August.

This represents the period of peak nesting on Hutchinson Island. If other nesting months are included (May and September), 75 percent of all adults were captured during the nesting season.

Green turtles removed alive from the intake canal over the entire study period ranged in size from 20 to 108 cm SLCL (x = 36.9 + 15.1 cm) and 0.9 kg to 177.8 kg (Figures 18 and 19). Nearly all (96 percent) were 33

juveniles or sub-adults. Over 75 percent were 40 cm or less in length, and 60 percent weighed less than 10 pounds. These immature turtles exhi-bited distinct winter pulses suggesting migratory behavior (Table 4).

However, some immature green turtles were present throughout the year.

To date, only six adult green turtles (SLCL >83 cm; Witherington and Ehrhart, in press) have been removed from the canal; all were captured during or shortly after the nesting season.

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

Sex Ratios Since intake canal monitoring began in 1976, 198 adult loggerheads have been sexed. The smallest was 75.5 cm in length and was observed nesting on Hutchinson Island subsequent to her. capture in the canal.

Females predominated males by a ratio of 4.9: 1.0, which significantly departs from a 1: 1 ratio (X2, P<0.05). Consequently, temporal patterns in the number of adult loggerhead captures are heavily influenced by the numbers of females present. When sexes were separated, it is evident that males were relatively evenly distributed among different months,

[

1 I

whereas nearly 80 percent of the females were taken during the nesting season (May through September; Figure 20).

The number of adult loggerheads captured at the St. Lucie Plant increased appreciably after 1982. Between 1976 and 1982, an average of 7.4 adult loggerheads (+4.4; range = 2-15) were entrapped each year, whereas over the last five .years, an average of 30.0 adults per year

(+8.9; range = 19-40) were captured. This increase corresponds to a general rise in loggerhead nesting near the plant (Figure 21). The year 1986 represented the highest number of nests ever recorded, both for the entire island and at the plant site (Area 4), and more adult females (35) were entrapped in the canal than ever before. This association is not unexpected, because increased nearshore movement associated with nesting behavior increases the probability of a turtle detecting one of the intake structures and hence the probability of entrainment.- The addition of the third offshore intake structure, the largest of the three struc-tures, in 1982 also may have contributed to increased entrainment of adults.

Since September 1982, 258 juvenile and sub-adult loggerhead turtles captured in the canal have been sexed by Texas A 8 N University researchers using a bi oimmunoassay technique for blood serum testosterone. For the purpose of these analyses, Dr. Owens and his asso-ciates used 76 cm as the cutoff length between immature and adult turtles. Bioimmunoassay results indicate that for immature loggerheads removed from the St. Lucie Plant intake canal, females outnumbered ma'les 35

I by a ratio of 2.7: 1.0. The sex ratios of immature loggerheads captured in the Cape Canaveral ship channel (1.7:1.0) and the Indian River Lagoon

( 1.4:1.0) are also reported to be significantly skewed in favor of fema-les (X2, P<0.05; Wibbels et al., 1984).

Of the six adult green turtles captured since monitoring began, four were males and two were females. Six immature green turtles have been sexed through blood work; all have been females. Of the five adult leatherback turtles for which sex was recorded, two were females and three were males. The only hawksbill thus far sexed was a female. No sex information exists for Kemp's ridleys.

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

Concurrently, alternative capture techniques were evaluated and potential deterrent systems tested in the laboratory. During this period, capture efficiencies 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 be-tween the AIA 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 36

improved. Most turtles entering the canal are now caught within a few days of first sighting, and in many instances, turtles have been caught in the tangle nets without any prior sighting, suggesting residency times of less than 24 hours. Better utilization of currents and eddies, adjustments to tethering lines and multi-net deployments 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 sub-merged or the anchor cable pull,ed 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 headwalls, most turtles breaching the barrier net were not caught until they entered the intake wells of Units 1 and 2. Since the canal capture program began, about 15 percent of all turtles entrapped in the canal have been removed from the intake wells. Because of their relatively small sizes, a greater proportion of greens (47.6 percent) reached the plant than loggerheads (9.4 percent).

After completion of the security intrusion barrier in December 1986, most turtles larger than 30.5 cm in carapace width were prevented from reaching the intake wel ls. During 1987, only seven loggerheads were removed from the plant, all during January and February. These turtles were presumably tr apped north of the intrusion barrier (Figure 2) before it was completed. An additional 15 loggerheads were removed from the 37

canal west of the A1A barrier net during 1987; 12 were hand-captured at or near the intrusion barrier, two were caught in tangle nets set west of the A1A bridge, and one washed up along the bank. A total of 11 green turtles made it past the A1A barrier net during 1987. Nine were removed from the intake wells, one was hand-captured near the intrusion barrier and one was caught in a tangle net set west of the A1A bridge. Four Kemp's ridleys were also captured west of the A1A barrier net during 1987, all at the Unit 1 and 2 intake wells.

To maximize confinement of larger turtles to the easternmost section of the intake canal, and thereby increase overall capture efficiency, the A1A barrier net has been periodically surveyed and, as required, appropriate measures taken to ensure its integrity. Such an adjustment was made during August/September 1985 (ABI, 1987). During 1987, the barrier net had to be dismantled between April and June because of construction activities in the canal. It was ultimately replaced with a new net in November 1987.

Relative Condition Turtles" captured malitiess alive in the intake canal of the St. Lucie Plant were assigned a relative condition based on weight, activity, parasite infestation, barnacle coverage, wounds, injuries and any other abnor-which might have affected overall well-being (Table 6). During 1987, 86.3 percent (151) of all loggerheads found in the canal were alive and in good to excellent condition. Only 7.5 percent (13) of loggerhead captures involved individuals in fair or poor condition; 6.3 percent (11) of the loggerheads removed from the canal were dea'd.

38

Of the 35 green turtles removed from the intake canal during 1987, 85.7 percent (30) were in good to excellent condition, while only 14.3 percent (5) were in fair or poor condition. Three of the six Kemp's ridleys caught during 1987 were in good to excellent condition, one was in fair condition and two were dead. Both hawksbills captured during 1987 were in excellent condition.

Over the entire monitoring period, about 70 and 80 percent, respec-tively, of al 1 loggerhead and green captures have involved turtles in good to excellent condition (Table 6). Captures of individuals in fair to poor condition have occurred about 22 percent of the time for logger-heads and 13 percent of the time for greens. Al l of the hawksbil 1s and all but one 1 eatherback have been removed from the canal in good to excellent condition., Although 60 percent of the Kemp's ridleys have been in good to excellent condition, all categories have been represented in the catches.

Relative condition ratings can be influenced by a number of factors, some related and others unrelated to entrainment and/or entrapment in the intake canal. Ratings of good to excellent indicate that turtles have not been negatively impacted by their entrapment in the canal, at least as evidenced by physical appearance. Although ratings of fair or poor imply reduced vitality, the extent to which entrainment/entrapment is responsible is often indeterminable. In some instances, conditions responsible for lower ratings, such as injuries, obvi ously were sustained prior to entrainment.

39

During 1987, about 13 percent of all captures involved individuals with severe injuries, including mi ssing appendages, broken or mi ssing pieces of carapace or deep lacerations. However, nearly all of these were old, wel 1-healed wounds. Shark attacks appeared to have been responsible for a large percentage of the injuries, as evidenced by crescent-shaped bite marks. One turtle had obvious propeller scars on the carapace. Although many turtles removed from the canal during 1987 had one or more recent superficial abrasions to the carapace or skin, only two individuals appeared to have sustained serious injuries as a result of their entrainment/entrapment. Both were treated, held for observation and subsequently released.

Once in the canal, an individual's relative condition appears to be related to the length of time it remains entrapped (ABI, 1987). As indi-cated earlier, entrapment periods are relatively short for turtles remaining between the A1A barrier net and intake headwalls, while resi-dency times increase for those individuals breaching the barrier net.

Previous comparisons have demonstrated that the proportion of loggerheads in good to excellent condition is greater for individuals caught in the tangle nets than for individuals removed from the intake wells (ABI, 1987). Loggerheads have a tendency to orient against currents in the canal, often resting near submerged structures. For individuals west of the A1A bridge, this behavior prolongs their transport to the intake wells and thereby extends their residency times.

40

Because green turtles entrapped in the canal are relatively small, their movements are more easily influenced by currents. Individuals passing through the barrier net probably arrive at the intake wells in a relatively short amount of time. Consequently, the mean relative con-dition of green turtles caught by tangle nets does not differ appreciably from the mean condition of individuals removed from the intake wells (ABI, 1987).

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

Blood hemoglobin levels have been measured in turtles removed from the intake canal since September 1982. During 1987, values ranged from less than 4.0 to 14.9 g/100 ml (n=80). The mean for turtles in excellent condition was 10. 1 g/100 ml (+1.52; n=38), while the mean value for indi-viduals in fair condition was only 8.2 g/100 ml (+2.36; n=3). Although previous analyses have also i ndi cated a general association between rela-tive condition and hemoglobin value, the overlap in ranges between groups has been considerable (ABI, 1987). To date, there have been no significant differences in the mean Hb values between relative condition categori es.

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

Mortalities During 1987, 11 loggerhead mortalities (6.3 percent of all loggerhead captures) were recorded in the intake canal. Eight of these turtles were removed fr om the security intrusion barrier, two were found floating against the A1A barrier net and one washed up on the canal bank west of A1A. Two Kemp's ridley mortalities also occurred in the intake canal during 1987; one was removed from the intake wells and the, other from a turtle net. No mortalities to other speci es were recorded during 1987.

Over the entire 12 year monitoring period, 116 (7.7 percent) of the 1,322 loggerheads and 16 (7.0 percent) of the 227 green turtles entrapped in the canal were found dead (Table 2). Mortalities spanned the range of size classes for loggerheads (SLCL = 47.5-125 cm), while all green turtle mortalities involved juveniles less than 41 cm in length. The two juve-nile Kemp's ridley mortalities documented at the plant during 1987 were 42

the only deaths for this species since monitoring began; no leatherback or hawksbill mortalities have occurred at the St. Lucie Plant.

Mortalities have been closely monitored throughout the life of the canal capture program in an attempt to assign probable causes and corrective to reduce future occurrences. Previous take'ppropriate measures analyses of data collected from turtles captured between 1976 and 1986 identified drowning in nets, drowning in the intake pipes during periods of reduced intake flow, injuries sustained from dredging operations and injuries sustained from the mechanical rakes used in the intake wells as probable mortality factors (ABI, 1987). Although difficult to quantify, the entrapment and subsequent demise of injured or sick turtles also pro-bably accounts for a portion of observed mortalities.

Over the years, materials and procedures have been modified to reduce the potential for a turtle drowning during capture. Lead lines have been removed from the nets and deployment techniques altered to allow turtles easier movement after entanglement. Surveillance of the nets has also increased. However, even with these precautions, a turtle has occasionally drowned. In recent years, this has occurred primarily when a small turtle has become entangled with one or more larger indivi-duals, apparently restricting its movement and ability to surface. Such an incident occurred on 10 June 1987, as a juvenile Kemp's ridley became entangled in a net at night with two larger loggerheads. Over the 12 year history of the canal capture program, only eight of the more than 1,700 turtles entrapped in the canal have drowned as a result of netting activities.

Most recent mortalities in the intake canal apparently resulted from drownings at the A1A barrier net and the newly constructed security intrusion barrier. A dramatic increase in loggerhead mortalities between 1985 and 1986 (Table 2) was thought to have been related to adjustments made to the A1A barrier net during the latter part of 1985 (ABI, 1987).

Presumably, these adjustments increased the pr obability of a turtle drowning. As a preventive measure, large holes were cut in the barrier net to provide escape hatches for turtles trapped against it by strong currents. Concurrently, plans were made to install a new barrier net, using a different method of deployment.

As a result of the barrier net's general ineffectiveness during much of 1987, larger turtles which otherwise would have been confined east of the AlA bridge were permitted free access to that portion of the canal where capture efforts are less effective. Twelve of these turtles were eventually removed from the canal at the security intrusion barrier; eight were dead. The live individuals removed from the intrusion barrier were tangled in its mesh or otherwise pinned against it by strong currents, and generally showed signs of injuries or weakened condition.

Sick or injured turtles contacting the net below the water's surface may be unable to surface and thus are probably more susceptible to drowning than healthy individuals. Concurrent with the removal of the A1A barrier net, surveillance and capture efforts in the canal were intensified, including multi-net deployments west of A1A and deployment of nets over the weekends. No loggerhead captures occurred west of the A1A bridge after August 1987 and a new barrier net was installed during November of that year.

In addition to the 11 loggerhead mortalities recorded during 1987, two turtles removed from the canal in poor condition later died. Both were very emaciated and were so lethargic they could be hand-captured.

One had numerous old wounds. A necropsy performed on the individual without wounds provided no clues as to the cause of death. However, both

'f turtles had been in the canal for a relatively short period (based on daily observations), indicating they were sick before their entrapment.

Both were heavily encrusted with barnacles and had numerous parasites.

This is a condition often seen in stranded individuals where no apparent wounds or injuries are present and may be indicative of poor health. The capture of terminally ill turtles in the canal lends support to the idea that at least a portion of the mortalities occurring in the canal may be a result of pre-entrainment conditions. Undoubtedly, pre-existing injuries and illnesses contribute to some of the canal mortalities.

Two Kemp's ridley mortalities occurred in the intake canal during 1987. The drowning in the tangle net was discussed earlier. The other mortality was recorded at the plant intake wells. Similar to the con-dition of many of the loggerheads removed from the intrusion barrier, this individual was emaciated and apparently in ill health. Strong currents in the vi ci nity of the intake wells may have resulted in its drowning. Although a necropsy was performed, cause of death could not be positively determined.

45

0 Reca ture Incidents 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 12 year history of turtle entrapment at the St. Lucie Plant, 48 individuals (47 loggerheads and 1 green) 'have been removed from the canal more than once. Several other turtles with tag scars have also been removed, indicating that the actual number of recaptures may be higher.

Of the 47 individual loggerheads known to have been caught more than once, 33 were caught twice, six were caught three times, four were caught four times, two were captured six times and two were caught on seven separate occasions, yielding a total of 79 recapture incidents. Release site did not appear to have any effect on a turtle's pr obability 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 captur ed more than. once (r ange of SLCL = 47-89 cm).

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

Recapture intervals for loggerheads ranged from four to 858 days, with a mean of 143 days (+161.5 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 57 percent of all loggerhead recapture incidents occurred within 90 days of previous cap-46

ture and 91 percent within one year (Figure 22). The average interval between first and last capture was 245 days (+267.4 days). These data suggest that residency times of loggerheads within the nearshore habitat adjacent to the St. Luci e Plant are relatively short. Similar findings have been reported for loggerheads inhabiting the Mosquito/Indian River Lagoons of east-central Florida (Mendonca and Ehrhart, 1982).

SUMMARY

A gradient of increasing loggerhead turtle nest densities from north to south along the northern half of Hutchinson Island has been shown during all survey years. This gradient may result from variations in beach topography, offshore depth contours, distribution of nearshore reefs, onshore artificial lighting and human activity on the beach at night. Low nesting activity in the vicinity of the power plant during 1975 and from 1981 through 1983 was attributed to construction of power plant intake and discharge systems. Nesting returned to normal or above normal levels following both periods of construction. Power plant opera-tion, exclusive of intake/discharge construction, has had no significant effect on nest densities.

There have been considerable year-to-year fluctuations in loggerhead nesting activity on Hutchinson Island from 1971 through 1987.

Fluctuations are common at other rookeries and may result from overlapping of non-annual breeding populations. Despite these fluc-tuations, loggerhead nesting activity has remained relatively high during the last six years. No relationship between total nesting and power plant operation or intake/discharge construction was indicated.

47

Results of three years of tagging studies on Hutchinson Island indi-cated that an average of two nests per year were produced by each nesting loggerhead turtle. Based on this average, the nesting population of loggerhead turtles on the island has varied from approximately 1,400 individuals in 1977 to over 2,700 in 1986. Though temporal nesting pat-terns of the Hutchinson Island population may be influenced by fluc-tuations in water temperature, no significant effects due to power plant operation have been indicated.

Since nest surveys began in 1971, raccoon predation was considered the major cause of turtle nest destruction on Hutchinson Island. From 1971 through 1977, overall predation rates in the nine survey areas were between 21 and 44 percent. However, a pronounced decrease in raccoon predation occurred after 1977, and overall predation rates in the nine survey areas have not exceeded ten percent since 1979. Decreased preda-tion by raccoons probably reflects a decline in the raccoon population.

During 1987,. 72 green turtle and 18 leatherback turtle nests were recorded on Hutchinson Island. Green turtle nesting activity exhibited considerable annual fluctuations, as has been recorded at other rookeries, but has remained relatively high during the last six years.

Annual leatherback nest densities during the last eight survey years were higher than the previous four survey years.

During 1987, 175 loggerheads, 35 green turtles, 2 hawksbills and 6 Kemp's ridleys were removed from the St. Luci e Plant intake canal. Since 48

monitoring began in May 1976, 1,497 loggerhead, 227 green, 8 leatherback, 6 hawksbill and 10 Kemp's ridley turtles have been captured. Over the l i fe of the monitoring program, annual catches for loggerhead turtles have ranged from 33 in 1976 (partial year of pl ant 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 were attributed to natural variation in the occurrence of turtles in the vicinity of the offshore intake structures, rather than to any influence of the plant i tsel f.

Size-class di stributions of loggerhead turtles removed each year from the canal have consistently been predominated by juveniles and sub-adults between 50 and 70 cm in straight line carapace length. Most green turtles entrapped in the canal (over 75 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 femal es.

During 1987, about 86 percent of all loggerheads and green turtles removed from the canal were categorized by physical appearance as being in good to excel lent condition. Over the entire 12 year monitoring period, about 70 and 80 percent, respectively, of all loggerhead and green turtle captures have involved individuals in these categories; 22

percent of the loggerheads and 13 percent of the green turtles removed from the canal have been in fair or poor condition.

About 13 percent of the turtles removed from the intake canal during 1987 had severe injuries. However, it appeared that all but two of these injuries were sustained prior to entrapment. 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 entrapment.

During 1987, 22 loggerheads, 11 green turtles an'd 4 Kemp's ridleys swam west of the A1A bridge. The majority of the loggerheads were retrieved at a recently installed security intrusion barrier, while all but two of the green turtles and all of the Kemp's ridleys were removed from the canal at the intake wells. Since monitoring began, about 9 percent of all loggerhead and 48 percent of all green turtle captures have occurred at the intake wells.

During 1987, two Kemp's ridley and eleven loggerhead mortalities were recorded for the intake canal. This represented a substantial decrease in loggerhead mortalities from 1986. The majority of deaths during 1987 appeared to have resulted from drowning, although the exact causes of death could not be determined. The intrusion barrier was pro-bably responsible for eight of the eleven loggerhead mortalities, but these deaths appeared to be confined primarily to individuals with injuries or in a weakened condition.

50

Since intake canal monitoring began in 1976, 7.7 percent of the loggerheads and 7.0 percent of the green turtles removed from the canal were dead. The two Kemp's ridley mortalities in 1987 were the first recorded for this species since monitoring began. All of the leather-backs and hawksbi1 1 s captured at the St. Luci e Plant have been released alive into the ocean.

51

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52

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ABI (Applied Biology, Inc.). 1984a. Florida Power 8 Light Company, St.

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53

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~ ~

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54

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Futch, C.R. and S.E. Dwi nel 1. 1977. Nearshore marine ecol ogy at Hutchinson Island, Florida: 1971-1974. IV. Lancel ets and Fishes.

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55

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Worth, D.F., and J.B. Smith. 1976. Marine turtle nesting on Hutchinson Island, Florida, in 1973. Florida Marine Research. Publications 18:

1-17.

58

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

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r Figure 2. St. Lucie Plant cooling water intake and discharge system.

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thirty-six 1-km segments surveyed for sea turtle nesting,

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Hutchinson Island, 1971-1987.

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150 100 50 1 2 3 4 5 6 7 8 9 NORTH POWER PLANT SOUTH Figure 4. Hean annual number of loggerhead turtle nests in each of the nine 1.25-km-long survey areas, Hutchinson Island, 1971-1986, compared with number of nests during 1987. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1987 values (1980 data were excluded because not all areas were surveyed ).

0 300 250 200 R

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z 100 50 A BCDE FGH I J K L MNOPQRS TUVWXYZABCDEFGH I J ABCDEFGH I J NORTH 0 POWER PLANT SOUTH Figure 5. Hean annual number of loggerhead turtle nests in each of the thirty-six 1-km--long survey areas, Hutchinson Island, 1981-1986, compared with number of nests during 1987. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1987 values.

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z 300 200 100 ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHI ABCDEFGH J I J NORTH POWER PLANT SOUTH Figure 6. Hean annual number of loggerhead turtle emergences in each of the thirty-six 1-km-long survey areas, Hutchinson Island, 1981-1986, compared with number of emergences during 1987. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1987 values.

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40 20 ABC DEFG H I J KLMNOPQRSTU VWXY ZA BCDE FGH I J A B CDE FGH I J NORTH f'OWER PLANT SOUTH Figure 7. Nean annual loggerhead turtle nesting success (percentage of emergences that resulted in nests) for each of the thirty-six 1-km-long survey areas, Hutchinson Island, 1981-1986, compared w'ith nesting success during 1987.

Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1987 values'

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100 50 71 73 75 77 79 80 81 82 83 84 85 86 87 Figure 8. Number of loggerhead turtle nests in Areas 4 and 5, Hutchinson Island, 1971-1987. Arrows denote years during which intake/discharge construction occurred in Area 4.

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3000 2000 D

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z 10000 8000 6000 4000 2000 g 80 CO CO Llj O 60 O

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I-CO Uj 20 1981 1982 1983 1984 1985 1986 1987

9. Annual number of nests, number of emergences and nesting success along the entire 36.0-km-long Atlantic coastline of Hutchinson Island, 1981-1987.

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15 30 5 15 30 5 15 30 5 15 30 5 15 30 5 15 APR MAY JUN JUL AUG SEP Figure 10. Daily loggerhead turtle nesting activity and water temperature, Hutchinson Island, 1987.

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AREA 6 50 AREA 7 50 AREA 8 50 AREA 9 50 1971 1973 1975 1977 1979 1980 1981 1982 1983 19841985 1986 1987 Fi gure 11. Percentage of loggerhead turtle nests destroyed by raccoons in the nine 1.25-km-long survey areas, Hutchinson Island, 1971-1987.

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1971 1973 1975 1977 1979 1981 1982 1983 . 1984 1985 1986 1987 Figure 13. Number of green turtle and leatherback turtle nests, Hutchinson Island, 1971-1987.

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1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 Figure 14. Number of loggerhead and green turtles removed each year from the intake canal, St. Lucie Plant, 1976-1987.

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30 30 m

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20 20 10 10 JAN FEB MAR APR MAY JUN JUL AUG .SEP OCT NOV DEC MONTH OF CAPTURE Figure 16. Hean number of loggerheads captured each month, St. Lucie Plant intake canal, 1977-1986, compared with number of monthly captures during 1987. Horizontal lines are means, boxes enclose plus or minus one standard deviation, vertical lines are ranges, and closed circles are 1987 values.

300 200 200.

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100 100 c40 41-45 46-50 51-55 56-60 61-65 66-70 71-75 76-80 81-85 86-90 91-95 96- 101- 106- 111- 116-100 105 110 115 120 STRAIGHT LINE CARAPACE LENGTH (cm)

Figure 16. Length distribution (SLCL) of live loggerhead sea turtles (N= 1,278) removed for the first time from the intake canal, St. Lucie Plant, 1976-1987.

180 180 160 160 14O 140 0

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~20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101- 151- 201- 251- 301- 5350 150 200 250 300 350 WEIGHT (Ibs) figure 17. Weight distribution of live loggerhead sea turtles (N= 1,140) removed for the first time from the intake canal, St. Lucie Plant, 1976-1987.

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-15 16 26- 31- 36- 41 51- 56 66- 71 81- 86- 91- 96- 101- 106- 111 20 25 30 35 40 45 50 55 60 65 70 75 80 '85 90 95 100 105 110 115 STRAIGHT LINE CARAPACE LENGTH (cm)

Figure 18. Length distribution (SLCL) of live green turtles (N= 209) removed for the first time from the intake canal, St. Lucie Plant, 1976-1987.

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Figure 19. Weight distribution of live green turtles (N= 205) removed for the first time from the intake canal, St. Lucie Plant, 1976-1987.

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z 10 10 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH OF CAPTURE Figure 20. Numbers of adult loggerheads (N= 202), including recaptures, removed each month from the intake canal, St. Lucie Plant, 1976-1987.

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1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 Figure 21. Comparison of captures of adult female loggerheads in the intake canal, St. Lucie Plant, 1976-1987, and numbers of loggerhead nests in Area 4 adjacent to the plant.

No nesting data were collected in 1976 and 1978.

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Figure 22. Cumulative percentage of all loggerhead recaptures occurring within various time intervals between successive captures (N= 77) and first and last capture (N= 45), St. Lucie Plant intake canal, 1976-1987.

ESTIMATES OF THE NUMBERS OF LOGGERHEAD TURTLE NESTS ON HUTCHINSON ISLAND BASED ON SURVEYS OF NINE 1.25-KM-LONG SURVEY AREAS, 1971-1987, COMPARED TO THE ACTUAL NUMBER OF NESTS ON THE ISLAND, 1981-1987 Year 1971 1973 1975 1977 1979 1981 1982 1983 1984 1985 1986 1987 Number of nests in the nine 1420 1260 1493 932 1449 1031 1634 1592 1439 1623 1839 1645 1.25-km-long survey areas Extrapolation from the nine 4189 3717 4404 2749 4275 3041 4820 4696 4245 4788 5425 4853 survey areas to the entire island (see text)

Actual number of nests on 3115 4690 4743 4277 4877 5483 4623 the entire island

T 2 TOTAL NUMBER OF SEA TURTLE URES AND (NUMBER OF DEAD)

TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987 S ecies Year lo erhead reen leatherback hawksbill Kem 's ridle Total 1976 33(4) 33(4) 1977 8o(s) s(2) 86(7) 1978 138(19) 6(1) 148(20) 1979 173(13) 3(1) 176(14) 1980 116(5) 1O(3) 126(8) 1981 62(s) 32(2) 97(7) 1982 101(16) 110(16) 1983 119(4) 23(4) 142(8) 1984 148(3) 69(2) 22O(S) 1985 157(4) 14 172(4) 1986 195(27) 22(1) 220(28) 1987 175(11) 35 6(2) 218(13)

Total 1497(116) 227(16) 8(o) 6(o) 10(2) 1748(134)

Annual Meana 133.1 20.6 0.7 0.5 0.9 158.9 a

Excludes 1976 (partial year of plant operation).

TABLE TOTAL NUMBER AND (NUMBER OF D 0) LOGGERHEAD TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987 Month 1976 1977 1978 1979 1980 1981 1982 1983 January 13 19 24(3) 16 11(1) 6(2) 39 February 8(1) 11(2) 29(1) 21(2) 11(3) 11 13(1)

March 7 27(2) 11 14 6 14 1 April 5(2) 19(5) 17 10 14 May 2 1 3(1) 0 7 6 17(4)

June 0 5 10 3(1) 8(3) 6 7 7(1)

July 7(1) 4 0 27(2) 0 1 7 August 2 3 12 17(2) 12 6 2(1) 6 September 1 15(l) 1 8(1) 19 2(1) 9(1) 8(2)

October 7 9(1) 17(2) 15(3) 7 0 9(5) 17 November 5(3) 5 15(7) 12 4 0 4(2) 5 December 9 5 4 10 3 1(1) 12 Total 33(4) 80(5) 138(19) 173(13) 116(5) 62(5) 101(16) 119(4)

TABL (continued)

TOTAL NUMBER AND ( NUMBER OF DEAD) LOGGERHEAD TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987 Monthly Percent of Month 1984 1985 1986 1987 Total Mean Total Catcha January 13 11 15(2) 26(3) 193(11) 17.5 13.2 February 11 15 16(4) 11 157(14) 14.3 10.7 March 6 20 14(4) 8(1) 128(7) 11.6 8.7 April 2(1) 13 20(2) 24(3) 124(13) 11.3 8.5 May 7 16 12 23(1) 98(6) 8.2 6.6 June 28(1) 17 20(1) 26(1) 137(8) 11.4 9.4 July 12(1) 20(3) 26(2) 19(1) 130(10) 10.8 8.4 August 26 19(1) 34(6) 17(1) 156(11) 13.0 10.5 September 16 14 9(4) 106(10) 8.8 7.2 October 10 7 11(2) 112(13) 9.3 7.2 November 9 3 75(12) 6.3 4.8 December 8 2 10 81(1) 6.7 4.9 Total 148(3) 157(4) 195(27) 175(11) 1497(116) a Excludes 1976 (partial year of plant operation).

TOTAL NUMBER AND (NUMBER OF DEAD) GREEN TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987 Month 1976 1977 1978 1979 1980 1981 1982 1983 January 2 1 0 0 20(1) 8(1)

February 2(1) 2 1 5(1) 7 March 0 2 0 4(1) 3(2)

April 1(1) 0 1(1) 0 May 0 1(1) 0 June July August 2(1)

September October November 4(1)

December Total 5(2) 6(1) 3(1) 10(3) 32(2) 23(4)

TA 4 (continued)

TOTAL NUMBER AND (NUMBER OF DEAD) GREEN TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987 Monthly Percent of Month 1984 1985 1986 1987 Total Mean Total Catch January 37(l) 4 1 4 78(3) 7.1 34.4 February 10 1 1 1 34(2) 3.1 15.0 March 1 6(1) 3 20(4) 1.8 8.8 April 13(2) 1.2 5.7 May 4(1) 0.3 1.8 June 10(1) 0.8 4.4 July 0.6 3.1 August 9(1) 0.7 4.0 September 0.4 2.2 October 10 0.8 4 4 November 4(1) 18(2) 1.5 7.9 December 19 1.6 8.4 Total 69(2) 14 22(1) 35 227(16)

NUMBER OF MONTHLY CAPTURES BY SIZE CLASS FOR LIVE LOGGERHEAD TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987a Size classes SLCL in cm Juveniles/Sub-Adults Transition Adults Month 41-50 51-60 61-70 Total Percenta e 71-80 Percenta e 81-90 91-100 >100 Total Percenta e January 14 74 59 147 14.6 22 13.7 2 0 10 5.4 February 8 61 51 120 12.0 14 8.7 0 0 1.6 March 7 51 43 101 10.1 16 10.0 3 0 1.6 April 10 36 37 83 8.3 16 10.0 1 0 3.3 May 9 34 23 66 6.6 5.0 5 0 14 7.6 June 4 43 33 80 8.0 10 6.3 10 1 35 19.0 July 2 34 31 67 6.7 10 6.3 23 15 2 40 21.7 August 6 43 41 90 9.0 18 11. 3 22 13 1 36 19.6 September 2 39 31 72 7.2 5.6 6 2 14 7.6 October 34 31 72 7.2 15 9.4 10 1 1 12 6.5 November 19 21 43 4.3 8.7 3 0 3.3 December 36 23 63 6.3 5.0 2 0 2.7 Total 76 504 424 1004 74.5 160 11.9 116 61 7 184 13.6 a

No data were collected for 33 individuals.

T 6 RELATIVE CONDITION SEA TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT 1976 - 1987 Relative Lo erheads Greens k Hawksbills All s ecies condition Number Number Number X Number Number Number 260 17.4 68 30.0 1 12.5 1 10 4 66.6 334 19.1 340 22.7 39 17.2 2 20 1 16.6 382 21.9 438 29.3 72 31.7 6 75.0 3 30 1 16.6 520 29.7 258 17.2 23 10.1 1 12.5 1 10 283 16.2 76 5.1 6 2.6 1 10 83 4.7 116 7.7 16 7.0 2 20 134 7.7 9 0.6 3 1.3 12 0.7 TOTAL 1497 227 10 1748 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 condition otherwise unknown.