Distribution of Sea Turtles in Lavaca And

A Final Report

DISTRIBUTION OF SEA TURTLES IN LAVACA AND MATAGORDA BAYS, TEXAS - A PRELIMINARY SURVEY OF ECOLOGY AND TOXICOLOGY OF SEA TURTLES AS RELATED TO FORMOSA PLASTICS CORPORATION’S WASTEWATER DISCHARGE

Submitted by the Texas A&M Research Foundation Room 112, Bell Building University Drive and Wellborn Road College Station, Texas 77843-3578

to the Environmental Protection Agency Federal Activities Branch 1445 Ross Avenue Dallas, Texas 75202

Prepared by André M. Landry, Jr., David T. Costa, F. Leonard Kenyon, Karen E. St. John, Michael S. Coyne, and Marc C. Hadler Department of Marine Biology Texas A&M University at Galveston Galveston, Texas 77551

August 1997 i

EXECUTIVE SUMMARY

Results of a study assessing sea turtle use of Lavaca and Matagorda Bays and the potential for toxicological risk to these organisms from wastewater discharged by Formosa Plastics Corporation’s Point Comfort Plant are reported herein. Objectives of this research were to: 1) document historical occurrence and distribution of sea turtles in Lavaca and Matagorda Bays; 2) execute entanglement netting operations characterizing present-day distribution, population dynamics and toxicological risks of these protected species; and 3) generate preliminary baseline data on trace metal concentration in the blood of captured turtles. Historical occurrence and distribution of sea turtles in Lavaca and Matagorda Bays were documented through a variety of survey methods including: on-line bibliographic searches of sea turtle and fisheries literature; personal interviews with a former Texas Parks and Wildlife Department (TPWD) biologist and recreational fishing guide; questionnaires sent to commercial shrimp and crab fishermen, recreational fishing guides, and TPWD enforcement officers and biologists; advertisements in the Port Lavaca Wave newspaper and Sea Grant Program and Gulf Coast Conservation Association magazines targeting the marine user; and posters strategically placed at boat ramps, bait shops, stores and restaurants throughout the study area. Historical occurrence of sea turtles in the Matagorda Bay System during the last 20 years can be characterized as seasonal utilization of Matagorda Bay (south of its juncture with Lavaca Bay) by a limited assemblage of greens (Chelonia mydas), Kemp’s ridleys (Lepidochelys kempii), and loggerheads (Caretta caretta). Peak utilization of the System’s habitats typically occurred in lower reaches of Matagorda Bay and near Pass Cavallo. Historical occupation of Lavaca Bay by sea turtles appears to have been infrequent. Present-day distribution, population dynamics and toxicological risks of sea turtles were characterized through entanglement netting operations staged in the northwest corner of Matagorda Bay at its juncture with Lavaca Bay. These operations were conducted monthly from May through October 1996. Turtles taken in entanglement nets were identified to species and enumerated, meristically examined, equipped with flipper and PIT tags, and sampled for blood used in sex and trace metal assessments. Hydrographic and nekton surveys documented environmental conditions and prey availability, respectively, in the study area during entanglement netting operations. Approximately 500 entanglement net-hours (a net-hour being defined as each hour one 91.5-m entanglement net is fished at a monitoring station) of effort yielded 12 sea turtle captures comprised of 7 Kemp’s ridleys and 4 greens (one of which was captured twice). Captures occurred during 4 of 6 monitoring months, with May-July accounting for 10 of these. All turtles were netted in the northwest corner of Matagorda Bay adjacent to Magnolia and Indianola Beaches, immediately south of the mouth of Lavaca Bay. Peak CPUE (0.43 turtle/km-hr) was achieved in May, while capture rate during other months was noticeably reduced (0.0-0.25 turtle/km-hr). Kemp’s ridleys, the majority being juveniles typically ≤40 cm carapace length, were taken only May-July, All ridley constituents were wild (as opposed to captive-reared “headstarts”) whose sex was partitioned between three females and four males. Post pelagic cohorts (≤40 cm carapace length) comprised the green turtle assemblage whose capture was limited to June, July and September. Gender of three greens which could be sexed was one female and two males. A 37.5 cm green turtle originally netted in Matagorda Bay on 19 June 1996 was recaptured 28 July, during which time (38 days) it gained 2.6 cm and 1.25 kg. A second recapture involved a Kemp’s ridley, originally taken in Matagorda Bay on 26 July 1996, which was netted off the Sabine Pass, Texas beachfront on 20 May 1997. This ridley gained 0.9 cm and 0.9 kg during 298 days of liberty. ii

Sea turtle captures in Matagorda Bay during May-October 1996, when compared with those from a similar netting effort at Sabine Pass over the same period, reflected low relative abundance and catch rate. Sabine Pass yielded an overall CPUE nearly four times higher than that recorded in Matagorda Bay. However, abnormally high salinity conditions and westward expansion of a hypoxic/anoxic “dead” zone across the northwest Gulf may mean that 1996 catch statistics are conservative estimates of sea turtle occurrence in nearshore habitats such as Matagorda Bay and Sabine Pass. The 1996 catches, when combined with the aforementioned historical survey and literature on sea turtle natural history, suggest that Kemp’s ridley and green turtles taken in reduced abundances near Lavaca Bay during the present study probably represent remnants of larger assemblages that: 1) naturally occur in lower reaches of the Matagorda Bay System which possess habitats more conducive to a herbivorous life style (i.e., green turtle) or benthic feeding habits (i.e., Kemp’s ridley); and 2) prefer shallow, nearshore Gulf waters but were attracted to upper reaches of Matagorda Bay by abnormally high salinities which facilitated extended feeding opportunities in this area. These same factors suggest that long-term, wide-ranging occupation of Lavaca Bay by either species is much reduced from that expected in lower reaches of the Matagorda Bay System and nearshore Gulf. Trace metal analyses of 6 sea turtles (5 Kemp’s ridleys and 1 green) captured during the current study were compared with those conducted on 106 Kemp’s ridleys taken at Sabine Pass in 1995 and 1996. Four of five Matagorda Bay ridleys exhibited mercury concentrations exceeding both the mean and maximum levels detected in Sabine Pass conspecifics of similar size. One ridley possessed five times more mercury (181 ppb) than the maximum concentration (35.6 ppb) in Sabine Pass counterparts. Adding to this was the noticeable reduction in mercury exhibited by a ridley originally captured in Matagorda Bay and subsequently netted 298 days later at Sabine Pass. Mercury concentration in the only green turtle analyzed from Matagorda Bay was well above the mean value detected for Sabine Pass ridleys of similar size. Copper levels in Matagorda Bay ridleys never exceeded maximum concentrations exhibited by Sabine Pass counterparts but they were slightly higher than the mean value detected in the former. Lead concentrations from Matagorda Bay ridleys fell in line with those for Sabine Pass conspecifics. The most noteworthy result from silver analyses was an elevated concentration (well beyond that in all other blood samples from Matagorda Bay) in the ridley recaptured at Sabine Pass in 1997. Zinc concentrations were similar in turtles from both sites. Significance of trace metal findings generated by this study is difficult to assess due, in large part, to a research void in sea turtle toxicology and an incomplete understanding of the degree to which blood can be used as a barometer of bioaccumulation. Nevertheless, the present study provides an albeit preliminary but repeated trend for sea turtles (particularly Kemp’s ridleys) from Matagorda Bay to exhibit elevated mercury concentrations beyond those from a more “toxic free” site like the Sabine Pass beachfront. This preliminary finding is not unexpected since Lavaca and Matagorda Bay sediments containing mercury are reworked by benthic prey organisms which are eaten by shrimp, crabs and fish that serve as food for Kemp’s ridleys. Clarification of the toxicological risk potential inherent to sea turtles using areas within and adjacent to Lavaca Bay will be complete only after more information is available on: 1) sea turtle occurrence in the area of concern; and 2) significance of trace metal concentrations in blood of these protected species. Preliminary results from the present study mandate consideration be given to facilitating more detailed investigations of trace metal uptake by sea turtles occupying Lavaca-Matagorda Bay environs. iii

Table of Contents

P a ge Executive Summary i List of Tables iv List of Figures v List of Appendix Tables vi INTRODUCTION 1 MATERIALS AND METHODS 2 A. Historical Occurrence of Sea Turtles 2 B. Sea Turtle Capture and Related Activities 7 Netting areas 7 Entanglement netting 9 Turtle work-up 9 Tagging protocol 11 Blood sampling - sex and trace metal analysis 11 Habitat characterization 12 RESULTS 13 A. Historical Occurrence of Sea Turtles 13 Literature survey 13 Questionnaires and related surveys 13 TPWD field surveys 15 B. Sea Turtle Capture and Population Dynamics 17 Sea turtle capture effort 17 Sea turtle population dynamics 17 Tag-recapture and tracking 26 Trace metal analysis 28 Habitat characterization 34 Hydrographics 36 DISCUSSION 36 Historical Occurrence of Sea Turtles in Lavaca Bay 36 Present Occurrence of Sea Turtles in Matagorda Bay 38 Toxicological Risks to Sea Turtles 41 REFERENCES 44 iv

List of Tables T a ble P a ge 1 Sea turtles captured by the Texas Parks & Wildlife Department during seasonal 16 fishery surveys of the Matagorda Bay System from 1979-94. 2 Sea turtle species abundance and status across Matagorda Bay netting stations 21 during 1996. 3 Sea turtle species captured by entanglement netting operations in Matagorda Bay 22 during 1996. 4 Mercury concentration (ppb, wet weight) in whole blood of sea turtles captured 29 from Matagorda Bay and Sabine Pass during 1994-97. 5 Copper concentration (ppb, wet weight) in whole blood of sea turtles captured 30 from Matagorda Bay and Sabine Pass during 1994-97. 6 Lead concentration (ppb, wet weight) in whole blood of sea turtles captured from 31 Matagorda Bay and Sabine Pass during 1994-97. 7 Silver concentration (ppb, wet weight) in whole blood of sea turtles captured from 32 Matagorda Bay and Sabine Pass during 1994-97. 8 Zinc concentration (ppb, wet weight) in whole blood of sea turtles captured from 33 Matagorda Bay and Sabine Pass during 1994-97. 9 Comprehensive list of nekton taxa taken in trawl tows at Matagorda Bay stations 35 May-October 1996. v

List of Figures F i gure P a ge 1 Sample letter sent to fishing guides, crabbers, shrimpers, game wardens, and 3 TPWD employees. 2 Questionnaire sent to fishing guides, crabbers, shrimpers, game wardens, and 4 TPWD employees. 3 Letter sent to Texas Parks and Wildlife Department soliciting historical 5 information. 4 Newspaper/magazine advertisement seeking information on sea turtle occurrence 6 in Lavaca and Matagorda Bays. 5 Poster used to publicize Lavaca Bay sea turtle study. 8 6 Lavaca/Matagorda Bay Sea Turtle Study Area. 10 7 Monthly number of sea turtles captured versus entanglement netting effort at 18 Matagorda Bay during 1996. 8 Monthly number of Kemp’s ridley sea turtles captured versus entanglement netting 19 effort at Matagorda Bay during 1996. 9 Number of Kemp’s ridley sea turtles captured versus netting effort at Matagorda 20 Bay stations during May-October 1996. 10 Monthly Kemp’s ridley and green sea turtle catch-per-unit-effort (#turtles/km-hr) 23 at Matagorda Bay during 1996. 11 Monthly sea turtle catch-per-unit-effort (#turtles/km-hr) versus water temperature 24 (C) at Matagorda Bay during 1996. 12 Monthly Kemp’s ridley catch-per-unit-effort (#turtles/km-hr) versus blue crabs (# 25 crabs/5 min. tow) at Matagorda Bay during 1996. 13 Straight carapace length (cm) frequency for sea turtles netted at Matagorda Bay 27 during 1996. vi

List of Appendix Tables Appendix T a ble P a ge 1 Fishing guides contacted by Texas A&M University’s Lavaca Sea Turtle 47 Survey. 2 Crab fishermen contacted by Texas A&M University’s Lavaca Sea Turtle 48 Survey. 3 Shrimpers contacted by Texas A&M University’s Lavaca Sea Turtle 49 Survey. 4 Texas Parks and Wildlife Department personnel contacted by Texas 51 A&M University’s Lavaca Sea Turtle Survey. 5 High-use boat ramps on weekend days as recorded by Texas Parks & 52 Wildlife Department. 6 Replies received by the Lavaca Sea Turtle Survey to questionnaires, 53 posters and newspaper advertisements. 7 Nekton taxa taken in trawl tows at Matagorda Bay station 1 during May 54 1996. 8 Nekton taxa taken in trawl tows at Matagorda Bay station 1 during June 54 1996. 9 Nekton taxa taken in trawl tows at Matagorda Bay station 1 during July 55 1996. 10 Nekton taxa taken in trawl tows at Matagorda Bay station 1 during 55 August 1996. 11 Nekton taxa taken in trawl tows at Matagorda Bay station 1 during 56 September-October 1996. 12 Hydrographic conditions at Matagorda Bay netting sites during May- 57 October 1996. 13 Sea and meteorological conditions at Matagorda Bay netting sites during 58 May-October 1996. INTRODUCTION

Concern over possible exposure of endangered and/or threatened sea turtles to effluent discharged by Formosa Plastics Corporation’s (FPC) Point Comfort Plant into Lavaca Bay, Texas resulted in the National Marine Fisheries Service (NMFS) issuing a biological opinion, under the Endangered Species Act Section 7 Consultation, in this regard. This opinion, in citing possible negative impact to sea turtles from potentially harmful chemicals in FPC’s effluent, prompted NMFS and the Environmental Protection Agency (EPA) to mandate a study characterizing sea turtle use of Lavaca Bay and assessing the potential for toxicological harm to these protected species by FPC wastewater discharge. FPC committed funds for the study and entered into a cooperative agreement with EPA, NMFS and the Texas A&M Research Foundation to conduct a preliminary evaluation of the distribution and toxicology of Kemp’s ridley (Lepidochelys kempii), loggerhead (Caretta caretta) and green sea turtles (Chelonia mydas) in the Lavaca/Matagorda Bay System. The following report summarizes accomplishments and findings by Texas A&M University at Galveston (TAMUG), performing as an agent of the Texas A&M Research Foundation, in the aforementioned evaluation of sea turtle distribution in the Lavaca/ Matagorda Bay System. The scope of work conducted by TAMUG was three-fold: 1) to document the historical occurrence and distribution of sea turtles in Lavaca and Matagorda Bays; 2) using information from #1, to plan and execute entanglement netting operations characterizing present-day distribution, population dynamics and toxicological risk potential of these organisms; and 3) to develop a preliminary baseline data set on trace metal concentration found in the blood of turtles taken during entanglement netting operations. 2

MATERIALS AND METHODS A. Historical Occurrence of Sea Turtles Research efforts during January through May 1996 were devoted, in part, to gathering historical information on sea turtle occurrence in Lavaca and Matagorda Bays. A variety of survey methods was employed in developing this historical characterization. Initial efforts involved on-line bibliographic surveys of sea turtle and fisheries literature, with emphasis on locating technical references specifically dealing with distributional information on sea turtles in the Matagorda Bay System and/or Texas coastal waters. Concurrent with these literature surveys were meetings with Messrs. Steve Marwitz [former Texas Parks and Wildlife Department (TPWD) biologist who worked in the Port Lavaca area] and Robert Dooley (local fishing guide and naturalist) to identify local sources of information on sea turtle occurrence. Recreational fishing guides, commercial shrimp and crab fishermen, and TPWD law enforcement officers and biologists were the initial targets of this information-gathering effort. An introductory letter (Fig. 1), explaining the survey and need for historical information, and questionnaire (Fig. 2) seeking information on sea turtle sightings and/or incidental captures were developed for each target group. Names and address of local fishing guides were obtained from the Port Lavaca Chamber of Commerce. Similar information (Fig. 3) on shrimp and crab fishermen, TPWD law enforcement officers and biologists was accessed through the

TPWD Law Enforcement Office in Victoria, TX. Questionnaires and stamped return envelopes were subsequently sent to a random sampling of these targeted constituents (Appendix Tables 1-4). A newspaper/magazine advertisement (Fig. 4) and 1-800 telephone number were developed for use in soliciting additional information on sea turtle occurrence from the general public. One ad was placed in the Port Lavaca Wave, the largest of three newspapers with circulation throughout the Matagorda Bay System. This ad was run for two consecutive weeks to insure adequate circulation. A similar advertisement also was 3 Institute of Marine Life Sciences Texas Institute of Oceanography

Texas A&M University at Galveston Texas Institute of Oceanography 4700 Avenue U, Building 303 P. O. Box 1675 Galveston, Texas Galveston, Texas 77551-5923 77551-5923 (409)740-4423 (409)740-4423 (409)740-4717 FAX FAX (409) 740-4717 April 26, 1996

Nghia Xuan Cao P.O. Box 283 Palacios, TX 77465 Dear Nghia Xuan Cao: Texas A&M University, the Environmental Protection Agency, and National Marine Fisheries Service are conducting a collaborative study to determine the risk posed to sea turtles from Formosa Plastic Corporation’s wastewater discharge into Lavaca and Matagorda Bays. We are hoping to establish a historical record of sea turtle occurrence in these waters. One means of gathering this historical information is from shrimp fishermen who have worked or are currently working the Matagorda Bay complex. I would appreciate your completing the attached questionnaire and returning it along with any pertinent information on sea turtles occurrence in the enclosed envelope. I look forward to hearing from you and thank you in advance for your willingness to cooperate in this research.

Respectfully,

André M. Landry, Jr. Professor of Marine Biology

A Part of the Texas A&M University System

Figure 1. Sample letter sent to fishing guides, crabbers, shrimpers, game wardens, and TPWD employees. 4 Texas A&M University Have You Seen Any Sea Turtles?

Texas A&M University is conducting a survey on the historical occurrence of sea turtles in the Lavaca Bay area. If you have ever seen a turtle in this area or adjacent vicinity, we would like to hear from you. Please complete this questionnaire and return it in the enclosed envelope. Use a separate questionnaire for each turtle you have seen. Your assistance in this research program is greatly appreciated.

General Location of Sighting: Lavaca Bay______Matagorda Bay______Other______

Specific Location (provide any information possible, such as landmarks, lt./long., etc.):

Month and Year of sighting (if you do not remember exact date, please provide season and approximate year):

DESCRIPTION OF TURTLE: Size: Color: Other distinguishing features (please note presence or absence of flipper tags if possible):

May we contact you to learn more about your sighting? Yes ___ No ____. If yes, please provide the following information: Name: Address:

Daytime telephone: ( )

Do you know of someone seeing sea turtles in the Lavaca/Matagorda Bay area? If so, please provide the following information: Name: Address:

Daytime telephone: ( )

For more information regarding this study, contact: Dr. André M. Landry, Jr. or Karen St. John Lavaca Sea Turtle Survey Texas A&M University 4700 Avenue U, Bldg. 303 Galveston, TX 77551 (800)850-6376

Figure 2. Questionnaire sent to fishing guides, crabbers, shrimpers, game wardens, and TPWD employees. 5

February 14, 1996

Jim Dailey Texas Parks and Wildlife Department Palacios Field Station 2200 Harrison Palacios, TX 77465 Dear Jim: Thank you for agreeing to participate in our study of sea turtle occurrence in Matagorda and Lavaca Bays. As I mentioned on the telephone, Texas A&M University, the Environmental Protection Agency, and National Marine Fisheries Service are conducting a collaborative study to determine the risk posed to sea turtles from Formosa Plastics Corporation’s wastewater discharge into Lavaca and Matagorda Bay. We are hoping to use your vast knowledge and your department’s monitoring data to establish a historical record of sea turtle occurrence in these waters. Any information you and your technical staff can supply will be extremely helpful to this study. Names and addresses of others who may provide historical information on sea turtles will be appreciated. We are interested in any information you may have especially that for the last ten years. The specific data I request you provide are as follows:

• turtle captured in gill nets, seines and/or trawls in the Matagorda Bay complex by year and lat/long • boat ramp locations, broken down by high and low use, where TPWD conducts its creel censuses and intercept activities • information on crabbers working the Matagorda Bay complex, especially as it relates to salinity and its impact on where crabs and turtles may be found • hydrographic data on the Matagorda Bay complex, especially as it relates to salinity and its impact on where crabs and turtles may be found • names of shrimpers who might collaborate in the historical survey • names of TPWD representatives in Austin and Rockport who might facilitate our gaining access to Texas Game and Fish Commission Marine Division Reports and TPWD Coastal Fisheries Technical Reports in order to learn more about sea turtle occurrence in the Matagorda Bay complex • names of retired/relocated TPWD employees who worked in the Matagorda Bay area that may have some information on sea turtles Please include any other ideas you feel may benefit our study. Send any and all information you have to our Galveston, Texas address. I look forward to hearing from you and look forward to hearing from you in the future. Respectfully,

André M. Landry, Jr. Professor of Marine Biology

Figure 3. Letter sent to Texas Parks and Wildlife Department soliciting historical information. 6 SEA TURTLE SIGHTINGS

TEXAS A&M UNIVERSITY IS CONDUCTING RESEARCH ON SEA TURTLE OCCURRENCE IN MATAGORDA AND LAVACA BAYS IF YOU HAVE SEEN A SEA TURTLE IN THESE BAYS, PLEASE CONTACT:

Dr. André M. Landry, Jr. or Karen St. John Lavaca Sea Turtle Survey Texas A&M University 4700 Avenue U, Bldg. 303 Galveston, Texas 77551 or call 1-800-850-6376

Figure 4. Newspaper/magazine advertisement seeking information on sea turtle occurrence in Lavaca and Matagorda Bays. 7 featured in the Texas Shores, a quarterly magazine published by the Texas A&M University Sea Grant College Program for a readership interested in marine-related aspects of the Texas coast. This advertisement also was posted on-line as a Sea Grant news release and sent to the Gulf Coast Conservation Association, an organization of recreational fishermen of considerable membership, for publication in their monthly newsletter. These latter efforts guaranteed a larger coverage than that afforded by the Port Lavaca Wave. All ads listed an 1-800 number (1-800-850-6376) as a cost-effective means of information return. An answering machine was integrated into this number to insure that calls at night and on weekends were received. A color poster (Fig. 5) soliciting information on sea turtle sightings in Lavaca and Matagorda Bays also was created to intercept other potential sources of input. This poster contained the TAMUG address and 1-800 number as a means of providing said information. One hundred posters were printed, 64 of which were attached to appropriate structures at high- and low-use boat ramps, bait shops, convenience stores and restaurants throughout the Matagorda Bay System. Selection of high-use boat ramps (Appendix Table 5) at which posters were placed was facilitated by personnel from the TPWD Field Station in Palacios. Data on sea turtle capture in gill nets, seines and trawls deployed by the TPWD in the Matagorda Bay System during 1985-95 were obtained from the agency’s main office in Austin as a scientific source of information on historical occurrence and distribution of these organisms in the study area. In addition, hydrographic data, especially that related to salinity and its impact on distribution of sea turtles and/or their prey in the Matagorda Bay System, were obtained from TPWD. B. Sea Turtle Capture and Related Activities Netting areas: Sea turtle capture and habitat characterization activities were conducted along beachfront habitats comprising the northwest corner of Matagorda Bay proper (Fig. 6). Historic information on sea turtle distribution within the Matagorda Bay System and concurrent analysis of NMFS’ tracking data from turtles captured by TAMUG in 8

SEA TURTLE SIGHTINGS TEXAS A&M UNIVERSITY IS CONDUCTING RESEARCH ON SEA TURTLE OCCURRENCE IN MATAGORDA AND LAVACA BAYS

IF YOU HAVE SEEN A SEA TURTLE IN THESE BAYS, PLEASE CONTACT:

Dr. André M. Landry, Jr. or Karen St. John Lavaca Sea Turtle Survey Texas A&M University 4700 Avenue U, Bldg. 303 Galveston, Texas 77551

or call: 1-800-850-6376

Figure 5. Poster used to publicize Lavaca Bay sea turtle study. 9

Matagorda Bay never justified (from ecological and financial perspectives) occupation of Lavaca Bay locales for monitoring purposes. Five entanglement netting stations were established in Matagorda Bay (Fig. 6). Four stations (1a-1d) were within 800 m of beachfront habitat extending between the north and south entrances to Indianola Beach Park, a county park within the community of Magnolia Beach. Stations 1a-1c were positioned every 300 m along a gulfward transect running parallel to Indianola Beach Park and between private fishing piers extending bayward from the park. These three stations exhibited a water depth typically ≤1.2 m and a gentle-sloping, hard-sand bottom with scattered oyster reef outcroppings. Station 1d was located approximately 5 km south of station 1c. This station was 1200 m from shore where water depth ranged between 1.2 and 1.5 m over a sand bottom. Water currents at all these stations varied with wind speed and direction. Station 2 was located 250 m south of Sand Point and 2 km due east from station 1a (Fig. 6). Water depth at this station did not exceed 1.2 m while tidal flow was slight to moderate. Entanglement netting: Sea turtle capture was accomplished with 91.5-m long entanglement nets of different depth and mesh size specifications. These nets were 3.7 m deep with 12.7 cm bar mesh of #9 twisted nylon and 4.9 m deep with 25.4 cm bar mesh of #9 twisted nylon. Water depth and current dictated which net was used at each monitoring station. Monitoring stations were sampled during the day with one to three stationary entanglement nets (of similar specifications) set adjacent to one another along beachfront habitats for 6 to 12 hrs. Duration of net sets was largely dependent on weather and bay conditions.

Turtle work-up: Entangled turtles were immediately removed from nets and held for subsequent examination and tagging at a shore-based, Port O’Connor holding site. All turtles were visually examined to describe physical condition, note evidence of natural (i.e., shark predation) and man-induced trauma (propeller wounds, appendage mutilation, visible fish hooks, etc.), and determine whether captured Kemp’s ridleys were wild or 10 11 headstarted cohorts. Turtles were then measured, weighed, photographed and tagged. Straight carapace length and width were measured with forester’s calipers while over-the- curve carapace length and width were taken to the nearest 0.1 cm with a soft vinyl measuring tape. Weight was determined to the nearest 0.1 kg on a Tri-Coastal Industries, Inc. electronic hanging scale. Turtles were photographed with a 35-mm camera for documentation purposes and placed in fiberglass holding tanks partially filled with ambient sea water prior to being tagged. Tagging protocol: All turtles captured by TAMUG were released to NMFS personnel who then decided whether or not to equip these turtles with tracking gear (see Renaud et al. 1997 for a description of said gear). Immediately prior to their transfer to NMFS for tracking and/or subsequent release into Matagorda Bay, all turtles were tagged by TAMUG with an inconel tag (provided by NMFS/Miami) on the trailing edge of each front flipper and a PIT tag (provided by NMFS/Galveston) inserted subcutaneously into the dorsal side of the right front flipper. All tagged turtles were released at their original capture site by NMFS personnel. Flipper and PIT tag data were submitted to NMFS (Miami) on reporting forms entitled “NMFS/SEFC Marine Turtle Tagging Data (rehabilitated, netted or other release)” and “NMFS/SEFC Marine Turtle Tagged/ Recapture Data”. Blood sampling - sex and trace metal analysis: Blood samples used for sex determination and trace metal analysis were drawn immediately after turtles were removed from entanglement nets or (if this initial attempt failed) opportunistically during the holding period. Extraction methods developed by Owens and Ruiz (1980) were used in obtaining blood samples at an amount not to exceed 4% of the total body volume. Most blood samples were immediately centrifuged within 1 hr of collection to separate plasma from blood cells. Frozen blood cells were delivered to Dr. David Owens (Professor of Biology, Department of Biology, TAMU, College Station) who used serum testosterone concentration as an indicator of sex. Owens deployed a radioimmunoassay technique described by Wibbles (1988) to determine serum testosterone concentration. 12

Blood samples used in trace metal analysis were placed on ice, transferred to a 5 mL cryovial, and frozen at -10 C until analysis. Silver, lead, copper, zinc and mercury levels in the blood were measured utilizing class-100 laboratory techniques. Each analysis initially required that 1 g of blood be digested with ultra pure nitric acid (Orvik 1996). Silver, lead, copper and zinc levels were then determined using a Perkin Elmer 5100 graphite furnace atomic absorption spectrophotometer equipped with Zeeman background correction and L’vov platforms. Mercury was determined using an automated version of the cold vapor atomic fluorescence technique described by Gill and Bruland (1990). Blood samples taken by TAMUG were analyzed to develop a baseline data set on trace metal concentration. These analyses were conducted as part of a larger study funded by the Texas A&M Sea Grant College Program to characterize trace metal concentrations in Kemp’s ridleys from Texas waters. No attempt was made by or required of TAMUG in the existing contract between the University and EPA to compare these findings with results of Formosa Plastics Corporation’s bay monitoring study. Analysis for the presence of chlorinated hydrocarbons, benzene and polyaromatic hydrocarbons (PAHs) also was not required of nor performed by TAMUG. These latter analyses and those for trace metals were contracted to the NMFS Galveston Laboratory. Consult the NMFS final report for these results. Habitat characterization: Habitat characterization efforts consisted of: 1) hydrographic monitoring; and 2) nekton surveys. Hydrographic monitoring involved surface and bottom measurements taken at Station 1 thrice daily (early morning, noon and late afternoon) to characterize water temperature, salinity and conductivity. Water temperature (to the nearest 0.1 C), salinity (to the nearest 0.1 ppt) and conductivity (to the nearest 0.1 mS/cm) were measured with Hydrolab H-20 Water Quality Multiprobes. Visibility was recorded to the nearest 0.1 m using a Secchi disc. Meteorological conditions (i.e., cloud cover, wind speed/direction, and sea state) also were characterized concurrent with hydrographic measurements. 13

Three replicate tows of a 6.1-m otter trawl having 1.9 cm bar mesh netting throughout and a 0.6 cm bar mesh cod end were conducted to determine nektonic prey availability within the immediate netting area. Trawls were towed for 5 minutes, with resulting samples preserved in 10% formalin and returned to the lab for analysis. Each sample was sorted, with constituent organisms identified to the lowest possible taxon, measured (fish and commercially-important shrimp and crabs only), enumerated and recorded.

RESULTS

A. Historical Occurrence of Sea Turtles Literature survey: A literature survey of sea turtle occurrence in the Matagorda Bay System was conducted utilizing on-line bibliographies of sea turtle information and library card catalogs (both local and on-line). Current and historical occurrence of sea turtles were investigated along with local history of the Lavaca/Matagorda Bay area. Many sources documented the occurrence of sea turtles along the Texas coast (Neck 1978; Rabalais and Rabalais 1980), but few mentioned Lavaca Bay specifically. The most recent of these (Manzella and Williams 1992) was a NMFS publication of Kemp’s ridley distribution with maps illustrating this species’ strandings/sightings/captures along the Texas coast over the past 50 years; this reference included 53 reports from the Lavaca/Matagorda Bay vicinity. Another valuable reference was an article by Doughty (1984) which characterized the green sea turtle cannery located in Indianola on the shores of Lavaca Bay until its destruction by a hurricane in 1875. Two local history books on Indianola mention the cannery only in passing or not at all.

Questionnaires and related surveys: Fourteen responses were received from 115 questionnaires randomly mailed to fishing guides, shrimpers, crabbers and TPWD game wardens (Appendix Table 6). One half of these respondees reported never having seen sea turtles in the study area. The remaining seven responses are summarized below: 14

• Milton Do, a commercial shrimper, captured seven sea turtles in 44 years of shrimping. All captures occurred in May during the mid-to-late 1970’s approximately 1.7 to 2.6 km off the Sand Point beachfront in 1-2 m of water. • Game Warden James Lovett reported one stranded and one live-sighting of Kemp’s ridleys, both tagged and fairly small, from 1987 to 1991 in Matagorda Bay near Palacios. • Clyde Rhoden, a commercial shrimper, captured two unidentified sea turtles (both approximately 30 cm carapace length) in two separate drags north of Sand Point (about half way to the Alcoa Plant in Point Comfort) during June 1994. • Captain Brent Goyen, a recreational fishing guide, reported a stranded sea turtle near the Matagorda Bay Wells in May or June 1995. • Robbie Gregory, a recreational fishing guide, saw approximately 10 small (30 cm carapace length) sea turtles at the Matagorda Ship Channel jetties during Spring and Summer 1995. Gregory also reported occasional sightings of a larger sea turtle in the same area. • Captain Gary Geissel, a charter boat skipper, reported the hook-and-line capture of a tagged Kemp’s ridley, and sightings of a loggerhead and leatherback 3.2-4.8 km (2-3 miles) offshore Matagorda Island’s Sunday Beach during June 1996. • David Turowski, recreational fishing guide and flounder fisherman, annually sees 20 to 50 juvenile sea turtles in Matagorda and Espiritu Santo Bays from March to July and

September to December. These turtles were typically seen at night resting in dense sea grass areas. Turowski also routinely sees larger sea turtles during the day near Pass Cavallo in June-August. A total of six responses was received from newspaper advertisements, flyers and news releases. One response was a prank call while another reported a sea turtle stranding. The remaining calls were considered legitimate reports of live sea turtle sightings/incidental captures in the study area. A summary of these responses (Appendix Table 6) follows. 15

• An unidentified caller reported seeing a small green turtle at the Pass Cavallo jetties. • Ms. Alta Ritchit of Houston reported her daughter cast-netted a green sea turtle approximately 40 cm carapace length from 1.5-m deep water at a Port O’Connor fishing pier on 26 May 1996. • Victor Morales, Jr., a former commercial fisherman, recounted his first capture of a 14- cm sea turtle in a trawl just southeast of Sand Point during August 1980. He also reported incidental captures of sea turtles, some as large as 90 cm, in the immediate vicinity during the next 8 years. However, by 1989, Morales began taking increasing numbers of sea turtles (approximately 50 cm carapace length) from grass bed and oyster-shell bottoms in Espiritu Santo and San Antonio Bays during June through late August. These captures coincided with reductions in incidental take of sea turtles in Matagorda Bay, the latter being comprised of floating, dead individuals except for two 80-cm turtles stuck in his TED while trawling the mouth of Keller Bay during late Fall 1989. • An unidentified female fisherperson of Magnolia Beach reported the hook-and-line capture of five different Kemp’s ridleys of varying sizes from a private Magnolia Beach fishing pier along the west shore of Lavaca/Matagorda Bay in May 1996. Subsequent calls from this fisherperson confirmed that ridleys continued to be caught from the pier during the following week. These hook-and-line captures of Kemp’s ridleys played a significant role in Texas A&M University at Galveston’s plans to net the immediate vicinity. TPWD field surveys: Nekton surveys conducted in Lavaca and Matagorda Bays by TPWD personnel during 1979-94 yielded 6 incidental sea turtle captures comprised of 3 Kemp’s ridleys, 2 loggerheads and 1 green (Table 1). All of these captures were taken incidental to gill net (5 turtles) and trawl (1 turtle) operations in Matagorda or East Matagorda Bay. No sea turtles were taken during TPWD surveys of Lavaca Bay proper. 16

Table 1. Sea turtles captured by the Texas Parks & Wildlife Department during seasonal fishery surveys of the Matagorda Bay System from 1979-94.

Species Date Location Gear Loggerhead 6/5/79 Matagorda Bay Gill net Kemp's ridley 11/4/87 East Matagorda Bay Gill net Loggerhead 4/18/88 Matagorda Bay Trawl Kemp's ridley 10/6/93 Matagorda Bay Gill net Green 6/7/94 East Matagorda Bay Gill net Kemp's ridley 9/27/94 East Matagorda Bay Gill net 17

B. Sea Turtle Capture and Population Dynamics Sea turtle capture effort: Approximately 500 entanglement net-hours were achieved during six monitoring surveys of Matagorda Bay habitats (Figs. 7 and 8). Note: A netting hour is defined as each hour one 91.5-m long entanglement net is fished at a monitoring station. All but 20 of these net-hours was expended at the station 1 complex (1a-1d) of netting sites (Fig. 9). Monthly capture effort ranged from near 35 net-hours in September to 131 net-hours in July (Fig. 7). Months of reduced capture effort were those exhibiting weather-related restrictions to netting. Sea turtle population dynamics: TAMUG entanglement netting operations at Matagorda Bay stations 1 and 2 during May through October 1996 yielded 12 sea turtle captures (Tables 2 and 3) composed of 7 Kemp’s ridleys and 4 greens (one of which was captured twice). All sea turtles were wild constituents (versus captive-raised headstart individuals) taken alive at station 1 (Table 3). Sea turtle capture at Matagorda Pass stations varied with month and netting effort (Table 3 and Figs. 7-10). Captures occurred during 4 of 6 monitoring months (Figs. 7 and 8). May, June and July, in receiving 67% of the netting effort expended during the study, yielded 10 of 12 captures recorded across the station 1 complex of sites. September was the only other month in which sea turtles were taken. Peak CPUE (0.43 turtle/km-hr) was recorded during May (Fig. 10). CPUE’s during other months ranged from 0.0 (August and October) to 0.25 turtle/km-hr (June). Although sea turtle capture across monitoring sites was directly related to netting effort (Fig. 9), all monthly CPUE statistics were relatively low. The seven Kemp’s ridley captures (Table 3 and Figs. 8 and 10) occurred during May (3 individuals), June (1) and July (3). These captures coincided with rising water temperatures (Fig. 11); however, they failed to exhibit a discernible relationship with blue crab (the ridley’s preferred prey) availability (Fig. 12). This ridley assemblage ranged in straight carapace length from 31.5 to 58.4 cm (Table 3) and was largely comprised of post-pelagic juveniles ≤40 cm SCL) and one subadult (Fig. 13). None was headstarted 18 1 1 8 4 0 O S All Turtles Net-Hours A Month J J M

4 3 2 1 0 # Turtles # Figure 7. Monthly number of sea turtles captured versus entanglement netting effort at Matagorda Bay during 1996. 19 16 12 80 40 0 O S Ridleys Net-Hours A Month J J M

3 2 1 0 # Ridleys # Figure 8. Monthly number of Kemp's ridley sea turtles captured versus entanglement netting effort at Matagorda Bay during 1996. 20 18 12 60 0 2 1d 1c Station 1b Ridleys Net-Hours 1a

3 2 1 0 # Ridleys # Figure 9. Number of Kemp's ridley sea turtles captured versus netting effort at Matagorda Bay stations during May-October 1996. 21

Table 2. Sea turtle species abundance and status across Matagorda Bay netting stations during 1996.

Status Species W H Kemp' s ridley 7 0 Green 4 0 Green recapture 1 0 Loggerhead 0 0

Total Captures 12 0

# Tagged (NMFS) Radio/Sonic Kemp' s ridley 6 0 Green 3 0 Satellite Kemp' s ridley 1 0 Green 2 0

W - denotes wild turtle H - denotes headstarted turtle Table 3. Sea turtle species captured by entanglement netting operations in Matagorda Bay during 1996.

Capture Predicted WT Measurements (cm) Release Date Time Site Sex Species ID# Flipper Tag # PIT Tag # (kg) SCL SCW CCL CCW Radio Sonic Satellite Status Date Time 5/22/96 1225 1 male L. kempii PL96-5-1 SSK191 SSK192 1F7A3A6A43 4.85 33.5 31.0 34.7 35.0 yes yes no wild 5/28/96 1022 5/23/96 1010 1 male L. kempii PL96-5-2 SSK193 SSK194 1F7B0F5E79 5.36 32.8 31.7 33.8 36.1 yes yes no wild 5/28/96 1233 5/23/96 1413 1 male L. kempii PL96-5-3 SSK195 SSK196 1F7B132B28 21.74 58.4 57.0 61.2 64.7 no no yes wild 5/29/96 1600 6/19/96 0953 1 female L. kempii PL96-6-1 SSL903 SSL904 1F7A256E54 5.09 34.3 32.1 36.1 37.5 yes yes no wild 6/22/96 1153 6/19/96 1038 1 male L. kempii PL96-6-2 SSL905 SSL906 1F7A7F2147 7.62 37.5 31.4 39.8 36.1 yes yes no wild 6/20/96 1216 6/19/96 1141 1 female C. mydas PL96-6-3 SSL907 SSL908 1F7B100551 3.25 29.9 23.6 30.7 25.8 yes yes no wild 6/20/96 1334 7/23/96 1439 1 male L. kempii PL96-7-1 SSL945 SSL946 1F7A7B4A22 3.98 31.5 31.6 33.0 34.3 yes yes no wild 7/24/96 1216 7/25/96 0842 1 female L. kempii PL96-7-2 SSL947 SSL948 1F7A253F03 8.65 40.4 39.3 42.7 45.0 yes yes no wild 7/30/96 1058 7/26/96 1443 1 female L. kempii PL96-7-3 SSL949 SSL950 1F7A314F67 11.08 43.9 44.2 46.0 49.0 yes yes no wild 7/30/96 0927 7/28/96 1246 1 male C. mydas PL96-6-2 SSL905 SSL906 1F7A7F2147 8.87 40.1 33.5 42.5 36.9 yes yes no recapture 7/30/96 1212 9/29/96 1410 1 C. mydas PL96-9-1 SSM305 SSM306 1F7B487F1F 4.61 36.3 28.5 38.1 31.5 no no yes wild 10/1/96 1523 9/30/96 0918 1 C. mydas PL96-9-2 SSM307 SSM308 1F780F507D 5.49 35.0 28.8 37.0 33.2 no no yes wild 10/2/96 1153

Capture Statistics

All Months 7 wild Kemp's ridleys 4 wild Greens 1 Green recapture 12 total

May 3 wild Kemp's ridleys Jun 1 wild Kemp's ridleys 2 wild Greens Jul 3 wild Kemp's ridleys 1 Green recapture Sep/Oct 2 wild Greens 22 23 2 S-O A Greens Ridleys J 1 3 Month 2 J 1 3 M

0.6 0.4 0.2 # Turtles/km-hr # Figure 10. Monthly Kemp' ridley and green sea turtle catch-per-unit-effort (#turtles/km-hr) at Matagorda Bay during 1996. Number inside histogram denotes species abundance. 24 S-O A Water Temp Greens J Month Ridley s J M

0.6 0.4 0.2 # Turtles/km-hr # Figure 11. Monthly sea turtle catch-per-unit-effort (#turtles/km-hr) versus water temperature (C) at Figure 11. Matagorda Bay during 1996. 25 S-O A Ridleys Crab CPUE J Month J M

0.5 0.4 0.3 0.2 0.1 # Ridleys/km-hr # Figure 12. Monthly Kemp's ridley catch-per-unit-effort (#turtles/km-hr) versus blue crabs (# crabs/5 min. tow) at Matagorda Bay during 1996. 26

(those cohorts raised in captivity at the NMFS Galveston Laboratory for 1 year before being released into the wild). Predicted sex of these ridleys (Table 3) was partitioned into three females (34.3-43.9 cm SCL) and four males (31.5-58.4 cm SCL). Green turtles were taken (Table 3 and Figs 10 and 11) in June (2 individuals), July (recapture of an individual netted in June) and September (2 individuals). Like their ridley counterparts, these greens were probably post-pelagic recruits to Matagorda Bay, with all but one individual <40 cm SCL (Table 3 and Fig. 13). Capture of greens turtles, often considered a resident of bays along the mid to lower Texas coast, from Matagorda Bay occurred across a much wider range of water temperatures than did that for Kemp’s ridleys (Fig. 11). Gender of three green turtles (Table 3) which could be sexed was divided between two males (37.5 and 40.1 cm) and one female (29.9 cm). Tag-recapture and tracking: All 11 sea turtles captured at Matagorda Bay sites in 1996 were equipped with inconel flipper tags and PIT tags (Table 3) by TAMUG personnel prior to their transfer to NMFS biologists for subsequent attachment of tracking telemetry and eventual release. This tagging effort facilitated the identification of one recaptured individual during the 1996 monitoring period - a 37.5 cm SCL green turtle originally netted 19 June, released 1 day later, and recaptured at Matagorda Bay station 1 on 28 July. Growth of this green turtle during its 38 days of freedom was 2.6 cm SCL and 1.25 kg. Another recapture of a turtle captured, tagged and released in Matagorda Bay was achieved when a Kemp’s ridley, originally taken as a 43.9 cm SCL individual on 26 July 1996, was netted off the Sabine Pass, Texas beachfront on 20 May 1997. This ridley gained 0.9 cm and 0.9 kg over 298 days of liberty (Table 3). Each of the 11 sea turtles captured by TAMUG researchers was transferred to NMFS personnel conducting tracking studies of behavior and movement through the use of radio-/sonic- or satellite-telemetry (Table 3). Eight turtles, comprised of 6 Kemp’s ridleys ranging from 31.5 to 43.9 cm SCL and 2 greens of 29.9 and 37.5 cm SCL, were equipped with radio-/sonic-tags. The other three individuals, a 58.4 cm SCL ridley and 35.0 and 36.3 cm SCL greens, received satellite transmitters. All telemetry-equipped 27 60.0-69.9 Greens Ridleys 50.0-59.9 14% 20% 29% 40.0-49.9 60% Straight Carapace Length (cm) Length Straight Carapace 30.0-39.9 57% 20% 20.0-29.9

4 3 2 1 0 # Turtles # total catch. Straight carapace length (cm) frequency for sea turtles netted at Matagorda Bay during 1996. Number Figure 13. total inside the histogram bars denotes percent contribution of each length category to respective species' 28

turtles were released by NMFS within 6 days of original capture (Table 3). Results of NMFS tracking studies are contained within Renaud and Williams (1997). Trace metal analysis: Blood samples from five Kemp’s ridleys (one of which provided a second sample upon its recapture at Sabine Pass in May 1997) and one green turtle originally captured at Matagorda Bay sites were analyzed for mercury, copper, lead, silver and zinc concentration (Tables 4-8). Despite this small sample size, the resulting data set provides the first trace-metal baseline for turtles occurring in the Matagorda Bay System and enables preliminary comparisons with analytical findings on sea turtles from another segment of the Texas coast. Mercury concentration in whole blood of Matagorda Bay turtles ranged from 40.0 to 181.0 ppb and averaged 66.8 ppb (Table 4). All mercury levels, except the peak concentration, were below 50 ppb. Highest mercury concentrations (181 and 48.4 ppb) were found in relatively small ridley (40.4 cm) and green turtles (36.3 cm), respectively, whereas the largest turtle taken (a 58.4 cm ridley) yielded the lowest blood burden. Comparison of mercury levels detected in a 43.9 cm ridley originally captured in Matagorda Bay (26 July 1996) and recaptured at Sabine Pass (20 May 1997) yielded a 8.2 ppb decline in this element’s concentration. Copper levels averaged 596 ppb, with no turtle exhibiting a concentration >700 ppb (Table 5). Like that for mercury, peak copper concentrations (700 and 696 ppb) were detected in the two smallest turtles taken (32.8 and 31.5 cm ridleys, respectively). No other copper concentration-SCL relationships were apparent for ridleys. Copper concentration (570 ppb) in blood of the only green analyzed fell well within the range detected for ridleys. The ridley recaptured at Sabine Pass in 1997 experienced a 187 ppb decline from the initial analysis of this animal’s plasma (564 ppb) and, in so doing, yielded the lowest copper level (377 ppb) detected across blood samples. Lead levels ranged from 7.05 to 36.5 ppb and exhibited no detectable concentration- SCL trend (Table 6). Peak lead concentrations were found in a 40.4 cm ridley (36.5 ppb) and a 36.3 green turtle (18.0 ppb). All other lead levels were well below Table 4. Mercury concentration (ppb, wet weight) in whole blood of sea turtles captured from Matagorda Bay and Sabine Pass during 1994-97. The Sabine Pass capture lot was comprised of 106 Kemp’s ridleys. Matagorda Bay Sabine Pass Date Turtle # Species SCL Hg Hg Size Number (cm) Mean Min Max Class 5-23-96 PL96-5-2 L. kempii 32.8 47.5 14.2 5.5 33.7 30-35 20 5-23-96 PL96-5-3 L. kempii 58.4 40.0 40.3 30.9 49.7 55-60 2 7-23-96 PL96-7-1 L. kempii 31.5 40.1 14.2 5.5 33.7 30-35 20 7-25-96 PL96-7-2 L. kempii 40.4 181 17.0 8.4 35.6 40-45 11 7-26-96 PL96-7-3 L. kempii 43.9 43.6 17.0 8.4 35.6 40-45 11 5-20-97 PL96-7-3R* L. kempii 44.8 35.4 17.0 8.4 35.6 40-45 11 9-29-96 PL96-9-1 C. mydas 36.3 48.4 18.2 5.4 55.1 35-40 20