ML17228B132

Annual Environ Operating Rept 1994 - Vol I.

ML17228B132
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Issue date:	12/31/1994
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FLORIDA POWER L LIGHT COMPANY ST. LUCIE UNIT 2 ANNUAL ENVIRONM ENTAL OPERATING REPORT 1994 VOLUME 1 FLORIDA POWER AND LIGHT COMPANY JUNO BEACH, FLORIDA QUANTUM RESOURCES, INC.

PALM BEACH GARDENS, FLORIDA

ENVIRONMENTALOPERATING REPORT TABLE OF CONTENTS EXECUTIVE

SUMMARY

Introduction III Turtle Nesting Survey III Intake Canal Monitoring IV INTRODUCTION

Background

Area Description Plant Description TURTLES Introduction Materials and Methods Nesting Survey Intake Canal Monitoring Results and Discussion Nesting Survey 1994 Loggerhead Nesting Summary 11 Spatial Distribution of Loggerhead Turtle Nests 11 Long-Term Trends in Loggerhead Turtle Nesting 13 Seasonal Patterns of Loggerhead Turtle Nesting 14 Predation on Loggerhead Turtle Nests 15 1994 Green and Leatherback Nesting Summary 16 Trends in Green and Leatherback Turtle Nesting 16

Intake Canal Monitoring 18 1994 Canal Capture Summary 18 Relative Abundance and Temporal Distribution 18 Size Class Distributions 20 Sex Ratios 20 Capture Efficiencies 21 Relative Condition 22 Mortalities 24 Recapture Incidents 25 Summary 26 LITERATURE CITED 30 FIGURES 32 TABLES 47

EXECUTlVE

SUMMARY

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

Lucie County, Florida. The plant consists of two nuclear-fueled 839-MW units; Unit 1 was placed on-line in March 1976 and Unit 2 in May 1983. This document has been prepared to satisfy the requirements contained in the United States Nuclear Regulatory Commission's Appendix B Environmental Protection Plan (EPP) to St.

Lucie Unit 2 Facility Operating License No. NPF-16. This report discusses environmental protection activities related to sea turtles as required by Subsection 4.2 of the EPP. Other routine annual reporting requirements are addressed in Volume 2, also entitled "St. Lucie Unit 2 Annual Environmental Operating Report".

TURTLE NESTING SURVEY Since monitoring began in 1971, there have been considerable year-to-year fluctuations in sea turtle nesting activity on Hutchinson Island. However, data collected through 1994 have shown no long-term reductions in nesting on the island.

Relatively high nesting during recent years may actually reflect an increase in the number of nesting females in the study area. On a smaller scale, power plant operation has had no significant effect on nesting near the plant. Low nesting activity in 1975 and again in 1981 - 1983 in the vicinity of the plant was attributed to nighttime construction activities associated with installation of plant intake and discharge structures. Nesting returned to normal or above normal levels following both periods of construction . During 1991, daytime construction activities associated with velocity cap repairs had no apparent effect on nesting. Formal requirements to conduct nesting surveys expired in 1986 but this program was voluntarily continued through 1994 with agreement from federal and state agencies.

INTAKE CANAL MONITORING Since plant operation began in 1976, 3199 sea turtles (including recaptures) representing five different species have been removed from the intake canal. Of these 74.8 percent were loggerheads. Differences in the numbers of turtles found during different months and years have been attributed primarily to natural variation in the occurrences of turtles in the vicinity of the plant, rather than to operational influences of the plant itself. The majority of turtles removed from the intake canal (about 94 percent) were captured alive and released back into the ocean.

Ongoing evaluations and improvements to the canal capture program have substantially reduced mortalities of entrapped sea turtles during recent years. Turtles confined between the A1A barrier net and intake headwalls typically reside in the canal for a relatively short period prior to capture, and most are in good to excellent condition when caught.

I NTR 0 D 0 CT I 0 N BACKGROUND This document has been prepared to satisfy the requirements contained in the United States Nuclear Regulatory Commission's (NRC) Appendix B Environmental Protection Plan to St. Lucie Unit 2 Facility Operating License No. NPF-16.

St. Lucie Plant Units 1 and 2 use the Atlantic Ocean as a source of water for once-through condenser cooling. Since 1971, the potential environmental effects re-sulting from the intake and discharge of this water have been the subject of FPL-sponsored biotic studies at the site. Jurisdiction for sea turtle studies is with the NRC, which is considered to be the lead federal agency relative to consultation under the Endangered Species Act. Previous results dealing with sea turtle studies are con-tained in eleven annual environmental operating reports covering the period from 1983 through 1993 (ABI 1994). This report describes the 1994 environmental protec-tion activities related to sea turtles, as required by Subsection 4.2 of the St. Lucie Plant Unit 2 Environmental Protection Plan.

AREA DESCRIPTION The St. Lucie Plant is located on a 457-ha site on Hutchinson Island on Flori-da's east coast (Figures 1 and 2). The plant is approximately midway between the Ft.

Pierce and St. Lucie Inlets. It is bounded on the east side by the Atlantic Ocean and on the 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.

Elevations 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.

The Atlantic shoreline of Hutchinson Island is composed of sand and shell hash with intermittent rocky promontories protruding through the beach face along the southern end of the island. Submerged coquinoid rock formations parallel much of the island off the ocean beaches. The ocean bottom immediately offshore from the plant site consists primarily of sand and shell sediments. The Florida Current, which flows par-allel 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 839-MW nuclear-fueled electric generating units that use nearshore ocean waters for the plant's once-through condenser cooling water system. Water for the plant enters through three submerged intake structures lo-cated about 365 m offshore (Figure 2). Each of the intake structures is equipped with a velocity cap to minimize fish entrainment. From the intake structures, the water passes through submerged pipes (two 3.7 m and one 4.9 m in diameter) under the beach and dunes that lead to a 1,500-m long intake canal. This canal transports the water to the plant. After passing through the plant, the heated water is discharged into a 670-m long canal that leads to two buried discharge pipelines. These pass under-neath 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.

TURTLES INTRODUCTION Hutchinson Island, Florida, is an important rookery for the loggerhead turtle, Caretta caretta and also supports some nesting of the green turtle, Cheionia ~mdas dh I th h kt tt,~pht l .Allth p p t dhy state and federal statutes. The federal government has classified the loggerhead turtle as a threatened species. The leatherback turtle and the Florida nesting popula-tion of the green turtle are listed by the federal government as endangered species. It has been a prime concern of FPL that the construction and subsequent operation of the St. Lucie Plant would not adversely affect the Hutchinson Island rookery. Because of this concern, FPL has sponsored monitoring of marine turtle nesting activity on the island since 1971.

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

A modified daytime nesting survey was conducted in 1980 during the prelimi-nary construction of the ocean discharge structure for St. Lucie Plant Unit 2. During

this study, four of the previously established 1.25-km-long survey areas were moni-tored. Additionally, eggs from turtle nests potentially endangered by construction ac-tivities were relocated.

Every year from 1981 through 1994, 36 1-km-long survey areas comprising the entire island were monitored seven days a week during the nesting season (Figure 3).

The St. Lucie Plant Unit 2 discharge structure was installed during the 1981 nesting season. Offshore and beach construction of the Unit 2 intake structure proceeded throughout the 1982 nesting season and was completed near the end of the 1983 season. Construction activities associated with installation of both structures were similar to those conducted when Unit 1 intake and discharge structures were installed.

Eggs from turtle nests potentially endangered by construction activities were relocated during all three years.

During 1991, another major offshore construction project was undertaken to re-place damaged velocity caps on the three intake structures. A large elevated platform, from which repair activities were conducted, was erected around the three structures.

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

Requirement 4.2.1 of the NRC's St. Lucie Unit 2 Appendix B Environmental Pro-tection Plan was completed with submission of the 1986 nesting survey data (ABI, 1987). The nesting survey was continued voluntarily through 1994 with agreement from federal and state agencies. Results are presented in this report and discussed in relation to previous findings.

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

Previous publications and technical reports have presented findings of the nest-ing surveys, nest relocation activities and canal capture program (See ABI, 1994). Re-sults of studies to assess the effects of thermal discharges on hatchling swimming speed have also been reported (ABI, 1978). In July of 1994, responsibility for sea turtle research and conservation activities was transferred from Applied Biology, Inc. to Quantum Resources, Inc. Methodologies employed in both the nesting surveys and canal capture operations remained essentially unchanged so that data collected in 1994 and future years are directly comparable to previous years data. The purpose of this report is to 1) present 1994 sea turtle nesting survey data and summarize ob-served spatial and temporal nesting patterns since 1971, 2) document and summarize predation on turtle nests since 1971, and 3) present 1994 canal capture data and summarize comparable data collected since 1976.

MATERIALS AND METHODS

~Ni S Methodologies used during previous turtle nesting surveys on Hutchinson Is-land were described in earlier reports (ABI 1994). Methods used during the 1994 sur-vey were designed to allow comparisons with these previous studies.

The only significant change in nesting survey methods for 1994 was that, begin-ning July 1, only areas A - S were surveyed by Quantum Resources biologists (Figure 3). Data reported herein includes the full nesting season data for areas A - S and data for areas T - JJ through June 30. Data supplied by Ecological Associates, Inc. are used to provide whole island nesting totals in Figures 8, 11, and 12.

On 11 April 1994, a preliminary nest survey was conducted along Hutchinson Island from the Ft. Pierce Inlet south to the St. Lucie Inlet. Four leatherback turtle nests were found on Hutchinson Island prior to the beginning of formal nesting surveys.

From 15 April through 15 September, nest surveys were conducted on a daily basis.

The last nest recorded in area A - S was on 7 September. Biologists used small off-road motorcycles to survey the island each morning. New nests, non-nesting emer-gences (false crawls), and nests destroyed by predators were recorded for each of the 1-km-long survey areas (Figure 3). The 1.25-km-long survey areas established in ear-lier studies also were monitored so comparisons could be made with previous studies.

Data collected from beach nesting surveys were reported to the Florida Depart-ment of Environmental Protection (DEP) as part of the DEP Index Beach Nesting Sur-vey. In a cooperative effort, data from stranded turtles found during beach surveys

and the

~ were routinely provided to the Florida Department of Environmental Protection National Marine Fisheries Service (NMFS) through the Sea Turtle Stranding and Sal-vage Network.

Intake Canal Monitorin Most turtles entrapped in the St. Lucie Plant intake canal were removed by means of large-mesh tangle nets fished between the intake headwalls and a barrier net located at the Highway A1A bridge (Figure 2). Nets used during 1994 were from 30 to 40 m in length, 3 to 4 m deep and composed of 40 cm stretch mesh multifilament nylon. Large floats were attached to the surface, and unweighted lines used along the bottom. Turtles entangled in the nets generally remained at the water's surface until removed. Since its inception in 1976, the canal capture program has been under continual review and refinement in an attempt to minimize both entrapment times and injuries/mortalities to entrapped sea turtles. Prior to April 1990, turtle nets were usual-ly deployed on Monday mornings and retrieved on Friday afternoons. During periods of deployment, the nets were inspected for captures at least twice each day (mornings and afternoons). Additionally, St. Lucie Plant personnel checked the nets periodically, and biologists were notified immediately if a capture was observed. Sea turtle spe-cialists were on call 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day to retrieve captured turtles from the plant.

Beginning April 1990, after consultation with NMFS, net deployment was scaled back to daylight hours only. Concurrently, surveillance of the intake canal was in-creased and biologists remained on site for the duration of each day's netting activi-ties. This measure decreased response time for removal of entangled turtles from nets and provided an opportunity to improve daily assessments of turtle levels within

the canal. Records of daily canal observations were compared with capture data to assess capture efficiencies.

The A1A barrier net is u'sed to confine turtles to the easternmost section of the intake canal, where capture techniques have been most effective. This net is con-structed of large diameter.polypropylene rope and has a mesh size of 20.3 cm x 20.3 cm. A cable and series of large floats are used to keep the top of the net above the water's surface, and the bottom is anchored by a series of heavy blocks. The net is in-I clined at a slope of 3:1, with the bottom positioned upstream of the surface cable. This reduces bowing in the center and minimizes the risk of a weak or injured turtle being pinned underwater by strong currents.

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

The UIDS security barrier also consists of 20.3 cm x 20.3 cm mesh. Prior to comple-tion of the UIDS in December 1986, turtles uncontained by the A1A barrier net were usually removed from the canal at the intake wells of Units 1 and 2 (Figure 2). There they were retrieved by means of large mechanical rakes or specially designed nets.

Following construction of the UIDS barrier, all but the smallest individuals were un-able to reach the intake wells. Thus, as required, tangle nets were also deployed west of A1A. Improvements made to the A1A barrier net during 1990 have effectively con-fined all turtles larger than 32.5 cm carapace length (28.7 cm carapace width) to the eastern end of the canal.

I Formal daily inspections of the intake canal were made to determine the num-bers, locations and species of turtles present. Surface observations were augmented with periodic underwater inspections using SCUBA, particularly in and around the A1A barrier net.

In addition to the use of tangle nets, dip nets and hand captures by snorkel and SCUBA divers are also employed to capture turtles. Long handled dip nets, em-ployed from small boats and from the canal banks and headwall structures, are mod-erately effective in capturing turtles with carapace lengths of about 30 cm or less. Di-vers are employed to hand capture turtles whenever underwater visibility permits, and this technique has proven highly effective in the capture of turtles of all sizes, particu-larly less active individuals often found partially buried in the sediment in the vicinity of the A1A barrier net. Hand capture efforts have had a significant impact in reducing entrapment times for turtles in the intake canal.

Regardless of capture method, all turtles removed from the canal were identi-fied to species, measured, weighed, tagged and examined for overall condition (wounds, abnormalities, parasites, etc.). Beginning in July 1994, all turtles captured have been photographed prior to release, and the photographs retained for future ref-erence. Healthy turtles were released into the ocean the same day of capture. Sick or injured turtles were treated and occasionally held for observation prior to release.

When treatment was warranted, injections of antibiotics and vitamins were adminis-tered by permitted veterinarians. Resuscitation techniques were used if a turtle was found that appeared to have died recently. Beginning in 1982, necropsies were con-ducted on dead turtles found in fresh condition; three such necropsies were performed during 1994.

Florida Power 8 Light Company, Applied Biology, Inc., and Quantum Re-sources, Inc., continued to assist other sea turtle researchers in 1994. Since the pro-gram began, data, specimens and/or assistance have been given to the Florida De-partment of Environmental Protection, National Marine Fisheries Service, US Fish and Wildlife Service, US Army Corps of Engineers, Smithsonian Institution, South Caroli-na Wildlife and Marine Resources Division, Center for Sea Turtle Research (University of Florida), Florida Atlantic University, University of Central Florida, Texas A 8 M Uni-versity, University of Rhode Island, University of South Carolina, University of Illinois, University of Georgia, Virginia Institute of Marine Science, Western Atlantic Turtle Symposium, South Atlantic Fishery Management Council, Florida Marine Fisheries Commission, Harbor Branch Oceanographic Institution and the National Research 10

l, RESULTS AND DISCUSSION Nestin Surve 1994 Lo erhead Nestin Summar In 1994, 6607 Loggerhead turtle nests were recorded in the 36 1-km segments comprising Hutchinson Island (Figures 4 and 5). This total is in accordance with a general increase in loggerhead turtle nesting on Hutchinson Island since surveys began in 1971, although significant year to year fluctuations are evident.

S atial Distribution of Lo erhead Turtle Nests From 1981 through 1994, 36 1-km long segments comprising the island's coastline have been surveyed. The distribution of nests among these 36 survey areas has shown an increase in nesting from north to south along the northern half of the is-land (ABI, 1987, 1994). Along the southern half of the island there has either been no gradient or a gradient of decreasing nesting from north to south. Though beach dy-namics may sometimes affect the selection of nesting sites by loggerhead turtles, re-lationships between spatial nesting patterns and specific environmental conditions are often difficult to establish because of the interrelationship of the factors involved.

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

These "false crawls" (non-nesting emergences) may occur for many reasons and are commonly encountered at other rookeries. Davis and Whiting (1977) suggested that relatively high percentages of false crawls may reflect disturbances or unsatisfactory 11

l nesting beach characteristics. Therefore, certain factors may affect a turtle's prefer-ence 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 (Figures 6 and 7).

Historically, the pattern of loggerhead emergences on the island has generally paralleled the distribution of nests (ABI, 1987, 1994) ~ In contrast, nesting success by loggerheads along the island has typically lacked gradients (ABI,1987, 1994). Thus, the relatively high numbers of loggerhead nests observed in certain areas are usually a result of more turtles coming ashore in those areas rather than of more preferable nesting conditions being encountered by the turtles after they emerged. A variety of environmental factors (i.e., offshore bottom contours, distribution of reefs, type and ex-tent of dune vegetation, and human activity on the beach at night) may affect logger-head turtle emergence patterns and several have been reported to affect emergence patterns on Hutchinson Island (ABI, 1988, 1989). Undoubtedly, a combination of fac-tors account for the overall distribution of emergences and therefore the overall nest-ing pattern on the island.

Nesting surveys on Hutchinson Island were initiated in response to concerns that the operation of the St. Lucie Plant might negatively impact the local sea turtle rookery. Previous analysis, using log-likelihood tests of independence (G-test; Sokal and Rohlf, 1981) demonstrated that the construction of the plant's offshore intake and discharge structures significantly reduced nesting at the plant site during construction 12

l years 1975, 1981, 1982 and 1983 (ABI, 1987). However, nesting at the plant con-sistently returned to levels similar to or greater than those at a control site in years fol-lowing construction. During 1991 when offshore construction was restricted almost entirely to daylight hours, nests were more abundant at the plant site than at the con-trol site. Data collected through 1994 have shown that power plant operation exclu-sive of nighttime intake/discharge construction has had no apparent effect on nesting.

Lon -Term Trends in Lo erhead Turtle Nestin 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 (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 pro-portion of total nests deposited in the nine areas. This has then allowed extrapolation from the nine survey areas to the entire island for years prior to 1981.

From 1981 through 1993 the total number of nests in the nine areas varied from 32.5 to 35.6 percent of the total number of nests on the island . This is slightly higher than the 31.3 percent which would be expected based strictly on the proportion of lin-ear coastline comprised by the nine areas. Using the thirteen-year mean of 33.81 per-cent, estimates of the total number of nests on Hutchinson Island can be calculated by multiplying the number of nests in the nine areas by 2.958. This technique, when ap-plied to the nine survey areas during the thirteen years in which the entire island was surveyed, produced whole-island estimates within 5.3 percent of the actual number of 13

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

It is clear that loggerhead nesting activity on Hutchinson Island fluctuates con-siderably from year to year (Figure 8). Annual variations in nest densities also are common at other rookeries, and may result from non-annual reproductive behavior.

Nonetheless, data collected through 1994 suggest an overall increase in nesting on Hutchinson Island since surveys began in 1971. Total nesting activity was greatest during 1991 when 6,812 loggerhead nests were recorded. No relationships between total nesting activity and power plant operation or intake/discharge construction were indicated by year-to-year variations in total nesting on Hutchinson Island.

Seasonal Patterns of Lo erhead Turtle Nestin The loggerhead turtle nesting season usually begins between mid-April and early May, attains a maximum during June or July, and ends by mid-September (ABI, 1987). Nesting activity during 1994 followed this same pattern.

Cool water intrusions frequently occur over the continental shelf of southeast Florida during the summer (Smith, 1982). These intrusions may have been responsi-ble for the temporary declines in loggerhead turtle nesting activity previously observed on Hutchinson Island (ABI 1994). Though natural fluctuations in temperature have been shown to affect temporal nesting patterns on Hutchinson Island, there has been no indication that power plant operation has affected these temporal patterns (ABI, 1988).

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Predation on Lo erhead Turtle Nests Since nest surveys began in 1971, raccoon predation has been a major cause of turtle nest destruction on Hutchinson Island. Researchers at other locations have reported raccoon predation levels as high as 70 to nearly 100 percent (Hopkins et al.,

1979). Raccoon predation of loggerhead turtle nests on Hutchinson Island has not approached this level during any study year, though levels for individual 1.25-km-long areas have been as high as 80 percent. Overall predation rates for survey years 1971 through 1977 were between 21 and 44 percent, with a high of 44 percent recorded in 1973. A pronounced decrease in raccoon predation occurred after 1977, and overall predation rates for the nine areas have not exceeded 10 percent since 1979. A de-cline in predation rates on Hutchinson Island may be attributable to trapping pro-grams, construction activities, habitat loss or disease.

During 1994, 9.4 percent (286) of the loggerhead nests (n= 3035) in areas A - S were depredated by raccoons. As in previous years (ABI, 1994), predation of turtle nests was primarily restricted to the most undeveloped portion of the island (Figures 9 and 10).

Ghost crabs have been reported by numerous researchers as important preda-tors of sea turtle nests (Hopkins et al., 1979; Stancyk, 1982). Though turtle nests on Hutchinson Island probably have been depredated by ghost crabs since nesting sur-veys began in 1971, this source of nest destruction did not become apparent until 1983. Quantification of ghost crab predation was initiated the same year.

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I Overall predation rates by ghost crabs have varied from 0.1 to 2.1 percent from 1983 - 1993 (ABI, 1994). During 1994, 0.5 percent (14) of the loggerhead nests (n=3035) in areas A- S were depredated by ghost crabs (Figure 9). Nests destroyed by a combination of raccoon and ghost crab predation have been included as rac-coon predations in previous discussions. When these combination predations are in-cluded as crab predations, the overall predation rates by ghost crabs range from 0.4 to 3.2 percent. During 1994, 4.7 percent (143 nests) were destroyed by either ghost crabs or a combination of ghost crabs and raccoons.

1994 Green and Leatherback Nestin Summar In 1994, 195 green turtle and 52 leatherback turtle nests were recorded in the 36 1-km-segments comprising Hutchinson Island. Both these figures represent an all-time high since nesting surveys were initiated in 1971 (Figures 11 and 12) and may reflect an increase in the numbers of nesting females in the Hutchinson Island area.

Trends in Green and Leatherback Turtle Nestin Green and leatherback turtles also nest on Hutchinson Island, but in fewer num-bers than loggerhead turtles. Prior to 1981, both survey (nine 1.25-km-long sections) and inter-survey areas were monitored for the presence of green and leatherback nests. Thirty-one kilometers of beach from Area 1 south to the St. Lucie Inlet were in-cluded in that effort. During whole-island surveys from 1981 through 1993, only 2.6 percent (7) of the leatherback nests (n=266) and only 1.4 percent (12) of the green turtle nests (n=831) were recorded on the five kilometers of beach north of Area 1.

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l Therefore previous counts of green and leatherback nests within the 31 kilometers surveyed probably were not appreciably different from total densities for the entire is-land. Based on this assumption, green and leatherback nest densities may be com-pared among all survey years, except 1980, when less than 15 kilometers of beach were surveyed.

Prior to 1994, the number of nests observed on the island ranged from 5 to 146 for green turtles and from 1 to 44 for leatherbacks (Figures 11 and 12). 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. Leatherback turtles usually begin nesting in March or April and continue to nest through early to mid-July. Considerable fluctuations in green turtle nesting on the island have occurred among survey years (Figure 11). This is not un-usual since there are drastic year-to-year fluctuations in the numbers of green turtles nesting at other breeding grounds (Carr et al., 1982). Despite these fluctuations, data collected through 1994 suggest an overall increase in nesting since 1971 and may re-flect an increase in the number of nesting females in the Hutchinson Island area. Dur-ing 1994, 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, increased nesting during recent years (Figure 12) may reflect an overall in-crease in the number of nesting females in the Hutchinson Island area. During 1994, leatherback turtles primarily nested on the southern half of the island.

Intake Canal Monitorin Entrainment of sea turtles at the St. Lucie Plant has been attributed to the pre-sumed physical attractiveness of the offshore structures housing the intake pipes rather than to plant operating characteristics (ABI, 1980b and 1986). The velocity caps supported above the openings to each intake pipe eliminate vertical water en-trainment and substantially reduce current velocities near the structures by spreading horizontal draw over a wider area. Even when both units are operating at full capaci-ty, turtles must actively swim into the mouth of one of the intake pipes before they en-counter current velocities sufficiently strong to effect entrainment. Consequently, a turtle's entrapment relates primarily to the probability that it will detect and subse-quently enter one of the intake structures.

1994 Canal Ca ture Summar In 1994, a record 361 sea turtles were captured in the intake canal of the St.

Lucie Plant. Captures included 164 loggerheads, 193 green turtles, 2 Kemp's ridleys, and 2 leatherbacks. (Table 1)

Relative Abundance and Tem oral Distribution Since intake canal monitoring began in May 1976, 2394 loggerhead (including 150 recaptures), 751 green (including 27 recaptures), 17 leatherback, 24 Kemp's rid-ley and 13 hawksbill captures have taken place at the St. Lucie Plant. Annual catches for all species combined ranged from a low of 33 in 1976 (partial year of plant opera-tion and monitoring) to 361 in 1994.

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Except for 1993 and 1994, when the green turtle was the most abundant species in the canal, loggerheads have dominated annual captures. Since 1977, the first full year of plant operation, the number of loggerheads captured each year ranged from 62 in 1981 to 195 in 1986 (Figure 13). Numbers have exhibited considerable year-to-year fluctuations with no persistent trends evident.

The number of green turtles captured each year since 1977 have ranged from 3 in 1979 to a record high of 193 in 1994 (Figure 13). Increasing numbers of captures over the last three years may reflect an increase in the number of turtles inhabiting the nearshore coastal area near the plant or may simply represent natural variation. An-other possibility relates to changes in the physical characteristics of the intake struc-tures. As a result of a major reconstruction project undertaken in 1991, the structures may now be more attractive to green turtles, thereby increasing their probability of en-trainment. Additional years of capture data will be required before any long-term pop-ulation trends can be established.

During 1994, the monthly catch of loggerheads ranged from 5 (March) to 33 (July), with a monthly mean of 13.6 (Table 2). Over the entire monitoring period, monthly catches have ranged from 0 to 39, with the greatest number of captures oc-curring during January 1983.

During 1994, the monthly catch of green turtles ranged from 1 (June and September) to 68 (December ) with a monthly mean of 16.1 (Table 3). The December 1994 catch of 68 green turtles is the largest number of captures for this species for any month on record. Seasonal abundance patterns of green turtles have been much more pronounced than for loggerheads, with over 50 percent of all captures occurring between January and March.

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Catches of leatherbacks, hawksbills and Kemp's ridleys have been infrequent and scattered throughout the 19 year study period. Each species has shown rather pronounced seasonal occurrences; over 60 percent of all leatherbacks were captured in March and April, over 60 percent of the hawksbills were collected between July and September, and almost 90 percent of the Kemp's ridleys were caught between De-cember and April.

Size-Class Distributions The size-class distribution for loggerheads removed from the intake canal in 1994 is presented in Figure 14. The size-class distribution for green turtles removed from the intake canal in 1994 is presented in Figure 15. ABI (1994) presents size-class data for turtles removed from the intake canal from 1976-1993.

x R~los Of the 164 loggerheads captured in 1994, 112 were juveniles with a straight line carapace length (SLCL) less than or equal to 70 cm, 36 were adults (SLCL > 85 cm) and 16 were transitional (SLCL 71-85 cm). (Hirth 1980) The latter group proba-bly includes both mature and immature individuals. Of the 36 individuals classified as adults, 29 were females and 7 were males, with females predominating by a ratio of Of the 194 green turtles captured in 1994 all were juveniles or sub-adults (SLCL < 83 cm) (Witherington and Ehrhart 1989). The 2 leatherbacks captured in 1994 were both adult females (SLCL > 121 cm) (Hirth 1980). One juvenile Kemp's ri-dley and one adult female Kemp's ridley (SLCL > 60 cm) (Hirth 1980) were captured in 1994. ABI (1994) discusses sex ratio data for previous years.

20

Ca ture Efficiencies Netting methodologies have been under continual review and refinement as net materials, configurations arid placement have been varied in an effort to minimize sea turtle entrapment times. Additionally, alternative capture techniques have been evaluated, and potential deterrent systems tested in the laboratory. Current capture procedures have proven to provide a safe, efficient and cost-effective program for re-moving entrapped turtles from the intake canal.

Formal daily inspections of the intake canal are conducted every day that cap-ture nets are deployed (usually five days each week), and the number, location, and relative size of entrapped turtles are recorded on field observation forms. For the peri-

'd for which residence time data is available (July 1 to December 31, 1994), about 76 percent of the turtles entering the canal were caught within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of first sighting.

Because of differences in mean size, loggerheads typically resided in the canal for shorter periods than the smaller green turtles.

In July - December 1994, 100 percent of all loggerheads were captured within one week of first sighting, with a mean entrapment period of 1.47 days. Over that same period, green turtles, which are less easily entangled in the large mesh nets, had a mean entrapment time of 2.00 days. 96.9 percent of all green turtles were cap-tured within one week of first sighting. Better utilization of currents and eddies, adjust-ments to tethering lines, multi-net deployments and increased efforts to hand capture turtles have contributed to reduced entrapment time during recent years.

Entrapment times may be extended for turtles swimming past the A1A barrier net (ABI, 1987). Because capture efforts west of the A1 A bridge were generally less 21

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. Because of their relatively small sizes, virtually all the turtles reaching the intake wells are green turtles.

During 1994, 49 of the 194 green turtle captures (25.2 percent) occurred at the intake wells.

During 1994, 84.2 percent of all turtles entrapped in the canal were captured east of the A1A bridge, 253 by tangle nets and 51 by hand or dipnet capture. The ef-fective confinement of turtles east of A1A has been a major contributor to the high cap-ture efficiency achieved during recent years.

Relative Condition Turtles captured alive in the intake canal of the St. Lucie Plant were assigned a relative condition based on weight, activity, parasite infestation, barnacle coverage, wounds, injuries and any other abnormalities which might have affected overall vitali-ty. During 1994, 95.1 percent (156) of all loggerheads found in the canal were alive and in good condition. Only 4.9 percent (8) of loggerhead captures involved individu-als in fair or poor condition. Of the 194 green turtles removed from the intake canal during 1994, 174 (89.7 percent) were in good condition, 16 (8.2 percent) were in fair or poor condition, and 4 (2.1 percent) were dead. One of the 2 Kemp's ridleys cap-tured in 1994 was in fair condition and the other was in good condition. Both of the leatherbacks captured in 1994 were in good condition.

Relative condition ratings can be influenced by a number of factors, some relat-ed and others unrelated to entrainment and/or entrapment in the intake canal. A rat-ing of good indicates that turtles have not been negatively impacted by their entrap-ment in the canal, at least as evidenced by physical appearance. Although ratings of 22

fair or poor imply reduced vitality, the extent to which entrainment/entrapment is re-sponsible is often indeterminable. In some instances, conditions responsible for lower ratings, such as boat collision or fisheries gear entanglement injuries, obviously were sustained prior to entrainment.

During 1994, 14 of the 361 turtles captured (3.9 percent) had noticeable in-juries, such as missing appendages, broken or missing pieces of carapace or deep lacerations. Most of these were old, well-healed wounds, and did not require medical attention.

Of the 357 live removals during 1994, 343 were released into the ocean the day of capture. Six small green turtles which were very lethargic at the time of removal were held overnight for observation. Relatively low water and air temperatures at the time of capture were thought to be responsible for this condition. One of these turtles died overnight while being held for observation. The other five were released the fol-lowing day. Six turtles (3 loggerheads and 3 green turtles) in obvious ill health or suf-fering serious injuries were transported to Sea World of Florida for treatment and re-habilitation. One of the loggerheads had a penetrating crack in the carapace. The re-maining two loggerheads were noticeably underweight, lethargic and heavily infested with barnacles and leeches, a condition referred to as "diseased turtle syndrome."

This condition has been reported elsewhere (Ehrhart 1987), and is unrelated to en-trapment in the canal. X-rays of one of these loggerheads also revealed significant in-testinal blockage. Three small green turtles recovered from the intake wells in lethar-gic and underweight to emaciated condition were transported to Sea World. One of these turtles died during transport, one died in rehabilitation, and the other is recover-.

ing. Four green turtles with fibropapilloma were removed from the canal in 1994. Two turtles with extensive tumors were transferred to the Florida DEP for transportation to a 23

rehabilitation facility. Two turtles with minor tumors were tagged and released. Few turtles with fibropapillomas have been captured in the past at the St. Lucie Plant.

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

Over the entire 19 year monitoring period, 130 (5.4 percent) of the 2,394 logger-heads and 28 (3.7 percent) of the 751 green turtles entrapped in the canal were found dead. Mortalities spanned the range of size classes for loggerheads (SLCL = 47.5-103 cm), while all green turtle mortalities involved juveniles less than 42 cm in length.

The four Kemp's ridley mortalities documented at the plant during 1987 and 1988 were the only deaths for this species to date; no dead leatherback or hawksbill turtles have been recovered at the St. Lucie Plant.

Modifications to capture procedures, improvements to the A1A barrier net and virtual elimination of low flow conditions within the canal have resulted in a substantial reduction in sea turtle mortalities over the life of the canal capture program. Mortality 24

rate, expressed as the percentage of total captures involving dead animals, declined from 7.8 percent during the period 1976-1984 to 3.5 percent since 1984 (Table 1).

In 1994, four turtles were removed dead from the intake canal, for an overall mortality rate of 1.1%. All of the mortalities occurred in December 1994, and all in-volved small green turtles removed from the plant intake wells. Three of the dead turtles were recovered in fresh condition, and were transferred to DEP for necropsy.

All three were underweight or emaciated at time of death. An additional green turtle was severely decomposed when recovered, and no necropsy was performed.

The mortalities coincided with an unprecedented influx of green turtles in De-cember. Their small size allowed them to pass through the barrier net and UIDS barri-er. At the time the present barrier was designed, calculations indicated it would con-fine 95% of all turtles to the easternmost portion of the intake canal. The large in-creases in green turtle levels in recent years has significantly reduced the mean size of turtles captured in the canal, due to the much smaller average size of green turtles occurring in the intake canal as compared to loggerheads. Thus, the barrier net is not as effective in confining the majority of turtles to the east of A1A. Consultations are un-derway for barrier net design improvements to correct this situation.

Reca ture Incidents Since the St. Lucie Plant capture program began, most turtles removed from the intake canal have been tagged and released into the ocean at various locations along Hutchinson Island. Consequently, individual turtles can be identified as long as they retain their tags. Over the 19 year history of turtle entrapment at the St. Lucie Plant, 177 recaptures (150 loggerheads and 27 green turtles) have occurred, and a number 25

of turtles have been recaptured more than once. Several other turtles with tag scars have also been recovered, indicating that the actual number of recaptures may be higher. Occasionally, turtles'are captured that have been tagged by other re-searchers. One such capture occurred in 1994, a female leatherback with tags from French Guiana.

SUMMARY

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

In 1994, 6607 loggerhead turtle nests were recorded on Hutchinson Island.

There have been considerable year-to-year fluctuations in loggerhead nesting activity on Hutchinson Island from 1971 through 1994. Fluctuations are common at other rookeries and may result from non-annual reproductive behavior. Despite these fluc-tuations, loggerhead nesting activity has remained high during recent years and may reflect an overall increase in the number of nesting females in the Hutchinson Island 26

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area. No relationship between total nesting on the island and power plant operation or intake/discharge construction was indicated.

Temporal nesting patterns of the Hutchinson Island population may be influ-enced by natural, large scale fluctuations in water temperature, such as those pro-duced by the cool water intrusions that frequently occur over the continental shelf of southeast Florida during the nesting season. However, localized fluctuations in water temperature associated with power plant operation have had no apparent effect on nesting.

Since nesting surveys began in 1971, raccoon predation is 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 predation by raccoons probably reflects a decline in the raccoon population. Ghost crab predation on turtle nests may be more significant than previ-ously documented but remains relatively minor compared to raccoon predation.

During 1994, 195 green turtle and 52 leatherback turtle nests were recorded on Hutchinson Island, a new record for both species. Nesting activity by these two species has exhibited considerable annual fluctuations, as has been recorded at other rookeries, but has remained relatively high during recent years. This may reflect an overall increase in the number of nesting green and leatherback turtles in the Hutchinson Island area.

27

During 1994, 164 loggerheads, 193 green turtles, 2 leatherbacks, and 2 Kemps ridleys were removed from the St. Lucie Plant intake canal. Since monitoring began in May 1976, 2394 loggerhead, 751 green, 17 leatherback, 13 hawksbill and 24 Kemps ridley turtles have been captured. Over the life of the monitoring program, an-nual catches for loggerhead turtles have ranged from 33 in 1976 (partial year of plant operation and monitoring) to a high of 195 in 1986. Yearly catches of green turtles have ranged from 0 in 1976 to 194 in 1994. Differences in the number of turtles en-trapped during different years and months are attributed primarily to natural variation in the occurrence of turtles in the vicinity of the offshore intake structures, rather than to plant operating characteristics.

Size-class distributions of loggerhead turtles removed each year from the canal have consistently been predominated by juveniles between 50 and 70 cm in straight line carapace length. Over 75 percent of all green turtles entrapped in the canal 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 loggerheads caught in the canal continued to be biased towards females.

During 1994, about 95 and 88 percent, respectively, of all loggerheads and green turtles removed from the canal were categorized by physical appearance as being in good condition.

About 4 percent of the turtles removed form the intake canal during 1994 had substantial injuries, and most of those were apparently sustained prior to entrapment.

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

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

28

During 1994, 4 green turtle mortalities were recorded in the intake canal. Pro-gram modifications, including continual surveillance of tangle nets during periods of deployment, improvements to the integrity of the A1A barrier net and greater effort to hand capture turtles have contributed to a substantial decline in sea turtle mortalities during recent years.

29

LITERATURE CITED ABI (Applied Biology, Inc.) 1978. Ecological monitoring at the Florida Power & Light Co. St. Lucie Plant, annual report1977. Volumes I and II. AB-101. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Miami.

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

Light Co., Miami.

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

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

. 1987. Florida Power &. Light Company, St. Lucie Unit 2 annual environmental operating report 1986. AB-579. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Juno Beach.

. 1988. Florida Power & Light Company, St. Lucie Unit 2 annual environmental operating report 1987. AB-595. Prepared by Applied Biology, Inc. for Florida Power 8 Light Co., Juno Beach

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

. 1994. Florida Power & Light Company, St. Lucie Unit 2 annual environmental operating report 1993. AB-631. Prepared by Applied Biology, Inc. for Florida Power & Light Co., Juno Beach.

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

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

30

Ehr hart, L.M. 1987. Marine turtle mortality in the vicinity of Port Canaveral, Florida, 1977-84. In W.N. Witzell, editor, Ecology of East Florida Sea Turtles, pages 1-

20. NOAA Technical Report NMFS 53.

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

Hopkins, S.R., T.M. Murphy, Jr., K.B. Stansell and P.M. Wilkinson. 1979. Biotic and abiotic factors affecting nest mortality in the Atlantic loggerhead turtle.

Proceedings Annual Conference of Southeastern Fish and Wildlife Agencies 32:213-223.

Smith, N.P. 1982. Upwelling in Atlantic shelf waters of south Florida. Florida Scientist 45(2):125-138.

Sokal, R.R. and F.J. Rohlf. 1981. Biometry. The principles and practice of statistics in biological research. W.H. Freeman and Company, San Francisco. 859 pp.

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

Smithsonian Institution Press. Washington, D.C.

Witherington, B.E. and L.M. Ehrhart. 1989. Status and reproductive characteristics of green turtles (Chelonia ~rn das nesting in Florida. Pages 35t-352 in Ogren, L.,

F. Berry, K. Bjorndal, H. Kumpf, R. Mast, G. Medina, H. Reichart and R. Witham, editors. Proceedings of the Second Western Atlantic Turtle Symposium.

Mayaguez, Puerto Rico, 12-16 October 1987. NOAA Technical Memorandum NMFS-S EFC-226.

31

GULF OF MEXlCO 0

0 YASSS NEOIIEM10 0000 110O 0 1 SCALE r

Q St. Ludo Plant Rgure1. Location of the St. Lucie Piant.

32

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

33

FLPleneMel '

~

0

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~st Lucia Inlet Figure 3. Designation and location of nine 1.25-km segments and thirty-six 1-km segments surveyed for sea turtle nesting, Hutchinson Island, 1971-1992.

34

5 HESTS El EHERGEHCES 600 500 o 400 0

W zO 300 z

~ 200 0

100 A B C 0 E F G H 1 J K L H H 0 P 0 R S Power Plant Figure 4. Number of loggerhead turtle nests and emergences for areas A through S, Kutchinson Island, April through September 1994.

~ HESTS H EHERGEHCES 600 500 CO oR 400 W

U O 300 R

~ 200 0

100 T U V M X Y 2 AA BB CC DD EE FF GG HH Il JJ Figure 5. Number of loggerhead turtle nests and emergences for areas T through JJ, Hutchinson Island, April through June 1994.

70%

<a 60%

O O

50%

co 40%

a 10%

0%

A B G D E F G H I J K L M N 0 P Q R B pawer plant 0 Figure 6. Loggerhead tuNe nesting success (percentage of emergences resulting in nests) for areas A through S, Hutchinson Island, April through September 1994

70%

<a o) 60%

CO LU O

O Vl 50%

Q cn 40%

R 10%

0%

T U V W X Y Z A B C D E F G H I J A B C 0 E F G H I J Figure 7. Loggerhead turtle nesting success (percentage of emergences resulting in nests) for areas T through J J, Hutchinson Island, April through June 1 994.

V)

I gg 4000 R

0 W

~ 3000 R

19 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 Figure 8. Number of loggerhead turtle nests, Hutchinson Island 1971 through 1994. Values for 1971 through 1979 are estimates (see text),

values for 1981 through 1994 are from whole island surveys.

8 RACCOONS & CRABS H CRABS ONLY 8 RACCOONS ONLY 35%

30%

0 ttt 25%

I 20%

0 15%

10%

5%

0%

A B j

C D E F G H I J K L M N 0 P Q R S Power Rant Figure 9. Percentage of loggerhead turtle nests predated by raccoons and/or ghost crabs in areas A through S, Hutchinson Island, April through September 19

5.00%

El RACCOONS & CRABS Rl CRABS 4.50%

~ RACCOONS 4.00%

3.50%

O 3 00%

O I

u) 2.50%

~ 2.00%

0 1 50%

1.00%

0.50%

0.00%

T U V W X Y Z AA BB CC DD EE FF GG HH II JJ Figure 10. Percentage of loggerhead turtle nests predated by raccoons and/or ghost crabs in areas T through JJ, Hutchinson island, April through June 1994.

I 140 P- 120

< 1OO Q 8O 20 19 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 Figure 11. Number of green turtle nests, Hutchinson Island,1971 through 1994. Values for 1971 through 1979 are estimates (see text).

Values for 1981 through 1994 are from whole island surveys.

40 20 10 19 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 84 Figure 12. Number'of leatherback turtle nests, Hutchinson Island, 1971 through 1994. Values for 1971 through 1979 are estimates (see text).

Values for 1981 through 1994 are from whole island surveys.

~ LOGGERHEAO ~ GREEN 140 120 40 20 19 76 77 78 79 80 81 82 83 84 85 88 87 88 89 90 91 92 93 94 Figure 13. Number of loggerhead and green turtles removed each year from the intake canal, St. Lucle Plant, 1S76 through 1SS4.

45 40 O

25 0

IL m 20 D

K 15 10

.0

<41 41 - 46- 51 - 56- 61 - 66- 70- 76- 81- 86- 91 101- 106- >110 45 50 55 60 65 70 75 80 85 90 95 100 105 110 STRAIGHT LINE CARAPACE LENGTH lcm)

Figure 14. Length distribution (SLCL) of loggerhead turtles (N = 163) removed from the intake canal, St. Lucie Plant, 1994.

70 D

40 0

5 R

so 20 10 c15 15 ~ 25 ~ 35 21 ~ 45 5570

~ 31 51 51 55 51 55 71 75 51 55 101. 105 >110 01 20 25 30 35 40 55 50 55 50 75 50 55 00 0$ 105110 STRAIGHT LEONE CARAPACE LENeTH (cm)

Figure 15. Length distribution (SLCL) of green turtles (N = 194) removed from the intake canal, St. Lucie Plant, 1994.

TABLE 1 TOTAL NUMBER OF SEA TURTLE CAPTURES AND (NUMBER OF DEAD) TURTLES REMOVED FROM THE INTAKE CANAL ST. LUCIE PLANT, 1976 - 1994 Species YEAR loggerhead green leatherback hawks bill kemp's ridle Total 1976 33 (4} 33 {4}

1977 80 (5} 5 {2} 86 (7}

1978 138 (19} 6 {1} 148 (20) 1979 172 (13} 3 (1} 175 (14}

1980 116 (5} 10 (3} 126 (8}

1981 62 (5} 32 (2} 97 P}

1982 101 (16} 8 110 (16}

1983 119 (4} 23 {4} 142 (8}

1984 148 (3} 69 (2} 220 {5}

1985 157 (4} 14 172 (4}

1986 195 (27) 22 (1} 1 220 (28}

1987 175 (11) 35 6 (2} 218 (13}

1988 134 {6} 42 (2} 5 (2} 181 (10}

1989 111 {4) 17 (1} 2 133 (5}

1990 112 {1) 20 '(2} 132 (3}

1991 107 (1} 12 121 (1) 1992 123 (2} 61 (2} 187 (4}

1993 147 179 (1} 337 (1}

1994 164 193 (4} 361 {4)

Total 2394 {130} 751 (28} 17 13 24 (4} 3199 (162}

Annual Mean* 131.2 (7.2} 41.7 {1.6} 0.9 0.7 1.33 {0.2) 175.89 (9.0}

• Excludes 1976 (partial year of plant operation).

TABLE 2 TOTAL NUMBER OF LOGGERHEAD TURTLES REMOVED EACH MONTH FROM THE INTAKECANAL ST. LUCIE PLANT, 1977" - 1994 1977 Through 1994 Number of Percent of Standard Month Captures All Captures Minimum Maximum Mean Deviation 1994 January 304 12.9% 39 16.9 9 20 February 222 9.4% 29 12.3 5.5 9 March 195 8.3% 27 10.8 6.8 5 April 211 8.9% 24 11.7 6.8 13 May 200 8.5% 28 11.1 8.4 17 June 254 10.8% 30 14.1 8.9 8 July 235 10 0% 33 13.1 10 33 August 219 93% 34 12.2 9.2 24 September 149 6.3% 19 8.3 5.3 7 October 146 62% 17 8.1 5.3 14 November 104 4.4% 15 5.8 3.8 6 December 122 5.2% 13 6.8 4.1 8 Total 2361 39 164 Mean 196.8 10.9 13.7 Std. Deviation 57.7 7.7 8.5

'irst full year of plant operation. An additional 33 loggerheads were captured during 1976.

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I

TABLE 3 TOTAL NUMBER OF GREEN TURTLES REMOVED EACH MONTH FROM THE INTAKE CANAL ST. LUCIE PLANT, 1977* - 1994 1977 Through 1994 Number of Percent of Standard Month Captures All Captures Minimum Maximum Mean Deviation 1994 January 143 19.0% 37 7.9 10.3 25 February 109 145 28 6.1 7.8 23 March 94 12 5% 55 5.2 12.6 April 48 6.4 23 2.7 5.2 3 May 26 3.5% 8 1.4 2.5 8 June 23 3.1% 6 1.3 1.7 1 July 17 2.3% 6 0.9 1.6 6 August 19 2.5% 4 1.1 1.3 September 14 19% 6 0.8 1.4 1 October 59 7.9% 21 3.3 6.2 21 November 76 10 1% 29 4.2 7.4 29 December 123 16.4% 68 6.8 16.1 68 Total 751 68 193 Mean 62.6 3.5 16.1 Std. Deviation 45.6 7.9 19.3

'irst full year of plant operation.