Brief Project Overview:
The Science Consortium for Ocean Replenishment (SCORE) is a science-based approach to stocking hatchery-reared marine organisms to help rebuild depleted marine fisheries (marine fisheries enhancement). SCORE scientists are conducting research to resolve critical uncertainties about the effectiveness of culture-based marine enhancement as a fishery management tool. It is anticipated that significant progress will be made by SCORE scientists, leading to greater and greater success from marine enhancement programs in the U.S.

As scientific gains are made in understanding the potential, SCORE scientists have partnered with NMFS and regional fishery-management agencies to develop policy and apply fishery-enhancement science to rebuilding depleted coastal stocks. Linkages with local fishing communities provide the cadre of citizens needed to support and expand enhancement as a fishery management strategy. Much of the enhancement technology developed here will be supported by funds generated by contributions and license fees paid by stakeholders and user groups. To fully embrace and use stocking as a marine enhancement management tool, demonstrated success stories are needed in a few key states. SCORE research is planned and coordinated to achieve such successes. Built around the principles of “a responsible approach to marine stock enhancement” (Blankenship and Leber; and see Leber, 2002, 2004), SCORE scientists are conducting key experiments to resolve critical uncertainties about how to control the biological, ecological, and economic effectiveness of marine fisheries enhancement.

SCORE is an R&D initiative conducted by a consortium of national partners. It is a powerful alliance of scientists and fishery managers currently working in the field of marine stock enhancement in the U.S.A., which encourages improved utilization of their expertise and resources. Bringing these scientists and managers together through SCORE allows synergisms to develop that would not occur otherwise.

Multi-Year Contract Period and Relation to this Reporting Period

This Multi-Year contract commenced on July 1, 2004 for the 5-year period ending June 30, 2009. The funding period for this 3rd year of the Multi-Year contract is July 1, 2006 through June 30, 2007. This interim report covers progress made during the period July 1, 2006, through December 31, 2006.

Project Accomplishments:

Mote Marine Laboratory Progress ­ July through December 2006

Aquaculture Research to Develop Rearing Technology for SCORE Species:
Wild Strip Spawning Efforts with Common Snook:
The 2006 snook spawning season to produce juvenile snook for release-recapture experiments began on June 14 and ended on August 11, 2006. Designated spawning locations for this summer season included both Terra Ceia and Charlotte Harbor. A total of five spawning attempts were conducted resulting in the capture of approximately 561 adult brooders. From these spawning attempts, eggs and milt were collected and maintained separately to allow for subsequent genetic analyses of progeny from each mated pair. Fin clips were collected from each broodfish and shipped to Michael Tringali at the Florida Fish and Wildlife Conservation Commission (FWC) for microsatellite DNA (genetic fingerprint) analysis. Throughout this spawning season, approximately 980 mL of eggs (2.7 million) were obtained for experimental and production research trials. Fertilized eggs were stocked into multiple larval rearing tanks.

Controlled Maturation and Spawning of Common Snook:

Maturation Trials
In 2005 and throughout 2006, we continued our research to mature and spawn captive snook at Mote Aquaculture Park (MAP). Three large tanks (54,315 liters or 14,350 gallons per tank) were stocked with mature adult snook and two of those tanks (20-1 and 20-3) were included in a trial to manipulate temperature and photoperiod to induce maturation. Tank 20-1 was stocked with 15 fish (8 male:7 female) and tank 20-3 was stocked with 13 fish (5 male:8 female).

In November 2005, photo-thermal conditions were adjusted to simulate a winter light and temperature cycle (10 h light:14 h dark; 22 + 0.5°C) for two of the snook broodstock populations (tanks 20-1 and 20-3). These parameters were maintained for two months and then altered to simulate spring environmental conditions. An abrupt change in temperature and photoperiod was used for tank 20-1, whereas gradual adjustments were implemented for tank 20-3 (12 h light:12 h dark; 24 + 0.5°C). In March 2006, another abrupt change in temperature and photoperiod was made to simulate the snook’s natural spawning season (summer cycle).

One month following the summer conditioning period (14 h light:10 h dark; 30 + 0.5oC), the snook were sampled to assess the state of gonadal maturation. Oocyte samples were obtained from 9 females with oocytes ranging in size from 51-154 _m. The males were not freely expressing high volumes of milt; however, we were able to obtain small samples by manual expression or cannulation from a total of 11 males. Tanks 20-1 and 20-3 were sampled again in May of 2006. Males continued to produce very little milt and samples were obtained by manual expression or cannulation from 6 individuals. Oocytes samples ranging from 341.9-473.4 _m in diameter were obtained from 3 females. These females were injected with slow releasing GnRHa implants at a dose of 50 _g/kg. All hormone implants were provided by the University of Maryland’s Center of Marine Biotechnology and were administered according to the methods described by Zohar et al. (1996).

In June, we sampled both tanks again and found female oocyte diameters (341.9-447.1 _m) to be similar in size to those obtained from the May sampling. Eight females were implanted with GnRHa (3 females in 20-1 and 5 females in tank 20-3). There appeared to be an overall improvement in milt production, as well as in the number of individuals producing milt with samples obtained from 11 males. Captive broodstock were implanted and sampled again in July of 2006 with 50µg/kg of (5 females from 20-1 and 6 females from 20-3).

In late August we completed our final sampling of both 20-1 and 20-3 for the 2006 captive spawning season. Previous sampling dates were scheduled every four weeks; however, this final sampling was performed after six weeks to allow for an extended period between handling. Females were difficult to cannulate in August and most did not yield any oocytes, which may have been due to a buildup of scar tissue in the oviduct from repeated sampling. For this reason, females were implanted with a smaller dose of GnRHa (25 _g/kg) to keep higher amounts of gonadotropin in their systems for future sampling and/or spawning. We also implanted the males with 25 _g/kg, to stimulate increased sperm production. Seven males and seven females from tank 20-1 were implanted with GnRHa at 25 µg/kg. In tank 20-3, seven females (5 with 25 µg/kg and 2 with 50 µg/kg) and six males (25 µg/kg) were implanted.

Following the August sampling, the snook broodstock were short cycled through a winter/spring/summer photo-thermal regime (condensing their year). This was done to determine if we could spawn them out of phase with the usual time of the year when wild spawns are typically observed. In September, temperature and light was adjusted over a two week period from a summer to winter regime (22 + 0.5 °C and photoperiod of 11 hours light and 13 hours dark). Once acclimated, broodstock were held under these conditions for two months. Upon completion of this winter phase, the temperatures were slowly raised over a two week period from 22 to 24°C and photoperiod was manipulated to 12 hours of light and 12 hours of dark. The spring conditioning cycle was maintained for one month and in January 2007 the fish were moved into the summer cycle with another slow shift in temperature to 30°C, where they were maintained with a photoperiod of 13 hours light and 11 hours dark. Beginning in March 2007, the fish will be sampled every 6 weeks. The new sampling schedule hopes to provide enough time in between sampling for the snook to recover from handling stress.

Spawning Trials
Following implantation, the fish were allowed to spawn naturally in the tanks. Eggs were passively collected using an egg collector that skims floating eggs off the surface. In May, a small spawn was collected in both 20-1 and 20-3, three days post implantation. Approximately 5,000 eggs were collected from both tanks and fertilization and hatch rates were estimated at 100% and 98.6%, respectively. In June, we redesigned the collector bar in tank 20-3 to determine if we could improve the collection efficiency. Eggs were collected (112,000 to 128,299) from tank 20-3 on days 2, 3 and 6 post implantation. Fertilization ranged from 11.3-80.7% and hatch rates could not be estimated because larvae began hatching in the egg collectors. Larvae were stocked in experimental (3.5 L) and production (3300 L) tanks and were fed rotifers and copepods (Acartia tonsa). Larval trials were terminated 11 DAH due to water quality issues.

In July, the egg collector bar was redesigned in 20-1 and eggs were obtained (21,360 to 49,315) on days 4 and 5 post implantation, while fish in tank 20-3 spawned on days 2, 3 and 4 post implantation and eggs were collected (40,454 to 607,000). Fertilization ranged from 13.6 to 97.6%, with hatch rates ranging from 68.8 to 91%. Development appeared to be abnormal and survival was <5 DAH for all spawns generated from this sampling period.

In August the egg collector tanks were moved closer to the broodstock tanks to improve collection efficiency and insure that temperatures remained stable. Fish in tank 20-1 spawned 2 and 3 days post implantation (346,900 to 635,897 eggs), while tank 20-3 spawned 1 and 3 days post implantation (444,000 to 675,799 eggs). Fertilization rates ranged from 3.2 to 87.6%. Again, larvae were stocked into experimental (3.5 L) and production (3,300 L) tanks. Hatch rates could not be determined for most of the spawns with the exception of the secondary spawn originating from tank 20-1. The hatch rate for this spawn was estimated at 73.5%. Larval trials were terminated at <10 DAH due to poor survival and water quality issues.

Evaluate Stock Enhancement Impact in Sarasota Bay and Tampa Bay:

Refining release strategies to improve survival of released snook:
The manuscript describing a release technique to improve survival of stocked snook was published; the reference is:
Brennan, N.P., Leber, K.M., Darcy, M.C., 2006. Predator-free enclosures improve post-release survival of stocked common snook. Journal of Experimental Marine Biology and Ecology Volume 335 (2):302-311.

Test of Density-Dependency Effects with Hatchery-Reared Juvenile Snook Released in Critical Nursery Habitats:
Proposed work in this area has been completed. In September 2006, the following manuscript was submitted to the fishery journal indicated below; the manuscript was “accepted pending moderate revision” in January 2007:

Brennan, N. P., and K. M. Leber. In Review. Manipulations of stocking magnitude: addressing density dependence in juvenile populations of a marine carnivore. Reviews in Fisheries Science.

An oral presentation of this work was also given at the 3rd International Symposium on Stock Enhancement and Sea Ranching, in Seattle, WA, in September, 2006.

Refining Tag Technology with the Common Snook and Red Drum:

Adapting Tag Technology toward Stock Enhancement of the Common Snook
We are investigating the use of acoustic transmitters (Vemco, V8SC1L, 24 mm long) in juvenile (age-0) snook. Both hatchery and wild snook were implanted with transmitters to monitor movement patterns in 2004 and 2005. We are currently preparing a manuscript that details the tagging methods, movement patterns, and survival patterns of the sonic-tagged snook.

Use of hatchery-reared snook to establish inland pond fisheries in Southwest Florida.
In September 2006, N. Brennan conducted an assessment of the 2-acre pond at Mote Aquaculture Park in Sarasota, FL, where 40 14” snook were stocked two years prior. A small electro-fishing boat was used for sampling. Eleven snook were caught, all of which were larger than 22 inches TL. The largest captured was 31 inches TL. Results showed that there were approximately 31 of the hatchery-reared snook in the pond at the time of assessment.

Feeding Ecology of juvenile snook:

Experiment 1: Gastric evacuation rates of finfish and shellfish prey items consumed by juvenile snook
We conducted a laboratory-based study to evaluate gastric evacuation rates of different prey items consumed by juvenile snook to better understand snook feeding ecology. Wild snook were collected and acclimated in the laboratory prior to the feeding trials. Snook were fed various prey types and sizes and stomachs were sampled at predestined times to determine digestive status. The results of this study aid in our understanding of snook feeding ecology by providing insight into population energetic models, community interactions and physiological implications for the species. Currently we are preparing a manuscript for publication in the Journal of Experimental Marine Biology and Ecology to be submitted in spring 2007.

Fishery Independent Assessment of Adult Habitat:

Identify Recruitment of Hatchery Snook to Adult Populations in Sarasota Bay
We produced a manuscript entitled “Investigations of essential fish habitat using releases of cultured snook.” The manuscript is currently in revision and will soon be submitted to a scientific journal for peer review. In this study, we cross examined our results (survival and growth of hatchery-reared snook stocked into several habitats in Sarasota Bay) obtained from short-term sampling in juvenile habitats with results from collections made in adult snook habitats (samples obtained over the long-term, 1-8 years after stocking).

Fishery Dependent Sampling of Snook Population in Sarasota Bay:

9TH ANNUAL “SNOOK SHINDIG”
In October, 2006, snook stock enhancement project staff, in association with the Snook Foundation, conducted the 9th Annual Snook Research Roundup and Shindig BBQ”. Local anglers fished from 7:30 pm Friday night (October 20), through Saturday at noon. A total of 174 snook were captured from Sarasota Bay during this event, and of these one was a hatchery-reared snook and two were recaptures of tagged wild snook tagged earlier by MML biologists. These annual tournaments aid in our understanding of the effects of releases of hatchery-reared snook on the snook fishery in Sarasota, FL.

An evaluation of cannibalism risk in juvenile snook:
A manuscript entitled “Cryptic cannibalism in size-structured snook populations” was prepared during fall, 2006. This document used a three-fold approach to investigate cannibalism in snook: (1) phenotypic differences in small and large snook that evidences cannibalism potential for juvenile snook, (2) Field enclosure studies that documented size specific cannibalistic tendencies under various experimental treatments, and (3) a meta-analysis of published literature on snook diet that provided input into a model that simulated seasonal effects of age-0, age-1, and adult snook cannibalism on age-0 snook.

Assist Florida Fish and Wildlife Conservation Commission (FWC) with Strategic Planning for the FWC Marine Stock Enhancement Program:
In line with the short and long-term objectives of strategic planning for the Fish and Wildlife Conservation Commission’s marine stock enhancement program, several steps have been made toward (1) improving the effectiveness of FWC’s marine stock enhancement program, (2) adapting and refining the aspects of a “Responsible Approach to Marine Stock Enhancement” (Blankenship and Leber, 1995) that have not yet been fully implemented in Florida, and (3) identifying and prioritizing potential marine fish species for stock enhancement in Florida.

• Dr. Ken Leber (Mote Marine Laboratory [MML]) has been working closely with FWC’s Stock Enhancement program as a chief advisor and a co-leader in strategic planning and research planning. During this report period, a draft document entitled “Current Status and Opportunities for Stock Enhancement and Aquaculture in Florida” was prepared by K. Leber, and colleagues, for submission as part of a Florida Ocean Commission report to the Florida Legislature.
• In Summer and Fall 2006, SCORE project leaders, K. Leber and K. Main, participated in 5 planning meetings with FWC leadership to develop plans for establishing an FWC satellite stock enhancement hatchery complex at Mote Aquaculture Park under the supervision of Main, Leber and FWC staff.

Northwest Fisheries Science Center Progress ­ July through December 2006

Develop a Genetic Management Plan:

The following SCORE supported paper was published:
LeClair, L. L., S. F. Young and J. B. Shaklee, 2006. Allozyme and microsatellite DNA analysis of lingcod from Puget Sound, Washington and adjoining waters. Transactions of the American Fisheries Society, 135:6, 1631-1643.

The paper confirms that Puget Sound stocks are one genetically mixed stock.

Develop Culture Technology:
Given the reduced budget this year, SCORE Washington scientists had planned on concentrating on improving culture technology in two areas:
A) Scaling up Pacific Cod Hatchery techniques.
B) Determining optimal feeding timing in larval rockfish

The spawning season for Pacific cod is mid winter so little activity occurred during this reporting period. During the period of this report (July-December) no Pacific cod held in captivity (wild captured and F1 juveniles) were lost. In December, a sample of four fish were checked for maturation using an ultrasound machine. Two of the four fish appear to be maturing females. Unfortunately no research is planned on Pacific cod during FY07 due to a lack of a federal budget.

Due to a lack of pregnant female rockfish over the summer, the study to determine optimal feeding timing in larval rockfish was started for the third time in January 2007. This trial will be reported on in the next report.

Describe Life History Patterns and Ecological Interactions and Optimize Release Strategies:
Two studies on rockfish behavior were conducted opportunistically when juveniles from another project became available.

Brown rockfish: The hypothesis that the hatchery environment selects for bold behavioral phenotypes was tested in juvenile brown rockfish. While considerable behavioral variation was documented, selection on that variation was not detected. This work has been submitted for publication.

China rockfish: We observed captive juvenile china rockfish in order to learn about their basic behavior and ecology. Juveniles were site faithful and territorial, defending structure against conspecifics within the context of a size-based dominance hierarchy. Average growth did not differ whether we reared juveniles with or without structure, but rearing in barren as opposed to structured environments led to a greater size disparity among individuals. This study is being written up for publication.

Pacific Cod: Receivers were placed in an attempt to determine if Pacific cod released a year earlier would return to the spawning grounds used by their parents. Receivers will be retrieved and data downloaded in March after the spawning season is over.

Communicate Results and Network Stock Enhancement Researchers & Managers:
The 5-day long 3rd International Symposium on Stock Enhancement and Sea Ranching was held in Seattle during September 2006. This was a major meeting and feedback from participants indicated that it was a great success.

Results of the lingcod release in 2005 have led to the Washington Department of Fisheries and Wildlife to re-write their policy for marine fish enhancement. This is scheduled to be adopted in 2007. This will provide opportunities to increase release numbers of lingcod in Puget Sound, if funding is available to continue this program.

Papers Submitted or Published:
LeClair, L. L., S. F. Young and J. B. Shaklee, 2006. Allozyme and microsatellite DNA analysis of lingcod from Puget Sound, Washington and adjoining waters. Transactions of the American Fisheries Society, 135:6, 1631-1643.

Lee, JSF and Berejikian, B. Behavioural Syndrome Stability without Stability of Individual Behaviour: Consequences for Rockfish Stock Enhancement. Submitted to Animal Behaviour.

University of New Hampshire Progress ­ July through December 2006

The long-term goal of our winter flounder stock enhancement program is to accelerate recovery of the fishery by increasing spawning stock biomass. To meet this goal, we have developed a multidimensional research program designed to produce large numbers of high quality juveniles, to optimize release strategies, and to understand how habitat attributes affect movement and sexual differentiation of juvenile winter flounder. Elements of the program addressed in this reporting period have included:

Juvenile Fish Production:
We produced approximately 30,000 winter flounder from a wild-caught broodstock at the Coastal Marine Laboratory (CML). These fish were used in the acclimation cage study and in the two sex ratio laboratory experiments described below. We currently have about 400 one-year old flounder which will be used for telemetry studies in late summer/early fall.

Acclimation Cages/Predator Study:
Juvenile flatfish are vulnerable to a suite of predators, including many decapod crustaceans. For juvenile winter flounder, predation by green crabs Carcinus maenas is of special concern (Fairchild & Howell 2000). Flounder acclimation cages used at the release are a necessary tool that allows the stocked fish to adjust to their new environment (Fairchild and Howell 2004; Sulikowski et al. 2005, 2006), however they also can be detrimental by attracting predatory green crabs to the release site (Fairchild et al., in review). Modification of the release strategy is necessary to offset this problem and alternate release strategies are being investigated. For example, in August, we tested the idea that fish could be acclimated in cages for the required 48 hr period, then gently towed to an alternate release site 250 m downriver, and immediately released to offset crab aggregations. However, to ensure that the move would not adversely affect the fish, indicated by an increase in cortisol levels, the following experiment was conducted. A total of 6 small acclimation cages (0.1 m²) were each stocked with 50 fish (118 dph; mean TL = 40 + 8 mm; 102% density) and secured to the bottom by divers on August 8. Two days later, half of the cages were hauled to the surface and the fish were immediately snap frozen on dry ice. The other 3 cages were raised and tethered to the boat so that they were still submerged, and towed at < 1 kt to the alternate release site. There the cages were lowered to the bottom for 10 min to simulate release conditions, then raised, and all fish were snap frozen on dry ice. Samples for cortisol analysis were prepared according to Sulikowski et al. (2005), and are currently being processed. Results are expected within one month.

An overview of this predator-prey interaction and its implications to the release strategy was presented in September 2006 in Seattle, WA at the Third International Symposium on Stock Enhancement and Sea Ranching.

Temporal and spatial distribution of juvenile winter flounder in the estuary:
The objective of this study is to identify the areas within the estuary where juvenile fish are found and when, to characterize their habitat, and to study their temporal and spatial use of the estuary. In addition, cultured and wild juvenile movements are being compared. To accomplish this goal, juvenile winter flounder were anesthetized, fitted with acoustic tags (VEMCO V7-2L-R256 coded pinger tags), and released. Each acoustic transmitter emits a distinctive coded pulse (frequency 69 kHz) that is detected by a hydrophone, thereby allowing the fish’s location to be accurately determined, and the fish’s movements to be tracked over time.

Cultured vs. wild juveniles:
In order to describe fine-scale movements of juvenile winter flounder, a VEMCO VRAP system which automatically tracks tagged fish movements within a triangular array of buoys was deployed in the release area. This release on 28 November 2005 consisted of 2 wild fish (44.3 + 36.6 g; 151 + 49 mm) and 6 cultured fish (60.3 + 31.6 g; 153 + 18 mm), 2 of which had been acclimated in a cage (AC) for 48 hours. This group of fish was tracked for a total of 74 days until 10 February 2006. Though the receivers recorded continuously, the coded tags only pinged every 1-2 minutes. As such, there were times when the signals coincided simultaneously and the receiver could not distinguish the tags. Therefore, periodically fish were not located by the VRAP system even if they were within the range of the buoys. Also, due to the physical parameters of the narrow channel and the large tidal flux, we could not stretch the buoy triangle out very far. The fish did not, for the most part, remain within the VRAP range, and so we manually moved the receiver buoys so that we were tracking at least 2 fish at all times. This means that there is limited information on most of the fish released.

Non-acclimated cultured fish followed a similar pattern in which they quickly left the triangulation area. Although both AC fish left the triangulation area too, it appears that they did not emigrate as far as the non-acclimated cultured fish. The 2 wild fish remained in the general area throughout the entire tracking period. Though not statistically possible, wild fish 145 and AC cultured fish 149 were compared for possible trends. Generally, the cultured fish moved more frequently but shorter distances than the wild fish. Kernal analyses of home ranges showed that the AC cultured fish maintained a much smaller home range than the wild fish. In addition, small scale tidal movements were evident, especially with the wild fish, in that the fish moved onto the shallow flats with flooding tides, and back into the channels on ebbing tides.

Results from these tagging studies were presented in September 2006 in Lake Placid, NY at the annual meeting of the American Fisheries Society.

Wild juveniles:

Ten juvenile wild winter flounder were caught with beam trawl in the Hampton River in September 2006 and tagged at sea. Tagged fish were then impounded in acclimation cages for 48 hrs to ensure that the tags were secure and fish were healthy. Fish were released from the cages and tracking was done using an array of 6 submersible receivers (VR2s) positioned in the Hampton River and at the mouth of the estuary. Eighty percent of the fish remained in the immediate release area for the first two weeks. As time at large increased, several fish dispersed downriver, and the largest individual (age 2) left the estuary entirely. As of 31 December 2006, 7 of the 10 fish are still being tracked. Monitoring fish movements will continue until the batteries expire.

Sex ratio of juvenile winter flounder:

New laboratory experiment #1:
Because we still do not know if winter flounder exhibit TSD, we repeated the temperature controlled experiment using higher temperature treatments (10, 15 and 20°C). These span the range of temperatures experienced by post-metamorphic wild juveniles, as well as the range of temperatures used during the early juvenile stage in most winter flounder culture facilities (Howell and Litvak 2000). These treatments were set up in climate-controlled rooms at the UNH. Experimental units consisted of glass aquaria filled with 40 liters of filtered, UV sterilized sea water. Each of these static systems contained a carbon filter, aerator, gross particulate sponge filter, and was illuminated from above (24L:0D). Fifty cultured fish (69 dph; mean TL 17 + 3 mm) were stocked into each tank on 16 June 2006. Fish were monitored daily which included feeding (Gemma 0.3 mm), and measuring water temperature, dissolved oxygen, salinity, and total ammonia. Twenty liters of water in each aquarium were changed approximately weekly so that total ammonia levels never exceeded 1 ppm. Once the fish reached > 41 mm TL and gonadal differentiation was complete (Fairchild et al., in press), all fish were preserved in modified Davidson’s fixative. Currently these samples are waiting for processing and will be analyzed using Chi-square tests.

New laboratory experiment #2:
Juvenile winter flounder held at high stocking densities (Sulikowski et al. 2006) under constant light are physiologically stressed, and may result in increased aggressive behavior (Sakakura and Tsukamoto 2002). This aggressive behavior manifests in fin nipping (Fairchild and Howell 2001) causing some initial damage to the fins, which in turn is exacerbated because the stress leads to a decreased resistance to bacterial infection. To test this hypothesis, we conducted an experiment examining the effect of stocking density and photoperiod on the incidence of fin erosion.

The experiment followed the general experimental design and methodologies used by Fairchild and Howell (2001). A 2x3 randomized complete block experiment with 3 replicates was conducted for 10 weeks from 26 June to 11 September 2006 in which 57 dph flounder were stocked out into 2 photoperiod treatments (24L:0D, 12L:12D) and 3 density treatments (20, 100, 300%). Density was measured as the ratio of total fish area to tank bottom area. A total of 1,614 fish were used such that 13, 64, and 192 fish were stocked into each of the 20, 100, and 300 treatments, respectively. Aquaria consisted of 3-L plastic gardening pots with a 182 cm² bottom surface area set up in water tables and each supplied with individual water lines connected to a flow-through system. Overhead lights on timers provided the photoperiod treatment. Stocking densities were to be adjusted over time as the fish grow by moving the fish into progressively larger aquaria.

Fish were monitored daily which included feeding (Gemma 0.3 mm), removing excess waste and any mortalities, and measuring water temperature, dissolved oxygen and salinity. Every 3-4 weeks, 10 randomly selected fish from each replicate were removed. Fish were anesthetized (50 ppm MS-222), measured (TL) and weighed (wet weight). Each fish was photographed for caudal fin erosion analyses. Following data collection, fish were returned to their aquaria. The experiment was terminated after 10 weeks because too many fish had escaped from the experimental units and could not be traced back to their source.

After 10 weeks, there was no effect of stocking density or photoperiod on growth of juvenile winter flounder. In addition, survival was not affected by stocking density. However, survival was on average 10% higher each week in the 12L:12D photoperiod treatments than in the 24L:0D treatments, suggesting that juvenile winter flounder exposed to a continuous light cycle may be more stressed than those under a more natural lighting regime. Data are still being analyzed to determine if there is a relationship between stocking density, photoperiod, and caudal fin damage. Since we also were interested in the effects of stocking density on gender development, the fish from this experiment were saved (in modified Davidson’s fixative) and will be processed histologically to determine sex.

University of Southern Mississippi Gulf Coast Marine Laboratory Progress ­ July through December 2006

Objective 1: Select appropriate species:

Workplan summary:
The seatrout’s status as the most popular recreational fish in the Gulf of Mexico combined with its dependence on threatened inshore habitats make it potentially vulnerable to depletion. As such, USM along with the Mississippi Department of Marine Resources and recreational angling groups formed SPEC, the Seatrout Population Enhancement Cooperative, in 2004 to investigate the feasibility of using stock enhancement as an additional tool for management of the seatrout population in Mississippi.

Activity:
No further activity this time period.

Objective 2: Define Goals and Objectives of Enhancement, incorporating Regional Stock Rebuilding Goals:

Workplan summary:
The goal of SPEC is to develop the technology for culture and release of seatrout to determine whether or not stock enhancement is a feasible option for management of seatrout populations in Mississippi. Should stock enhancement be shown to be a feasible option, the tool, along with creel and season limits, will be added to the Mississippi Department of Marine Resources options for managing the seatrout population in Mississippi waters.

Activity:
No further activity this time period.

Objective 3: Develop a Genetic Management Plan:

Workplan summary:
Current objectives involve applying microsatellite markers known to be of use for seatrout to Mississippi seatrout to establish the population structure. Until the population structure is elucidated, hatchery procedures will involve using broodstock from a single site, releasing juveniles in the same site, and periodic rotation of broodstock to maintain genetic diversity. As the technology is developed, the genetic makeup of juveniles for release will be evaluated and the population structure of the receiving population will be monitored for changes. The development of a genetic tag that will allow tracing of a fish’s contribution to the wild population is desirable.

Activity:
The first broodstock rotation is scheduled to coincide with the completion of the new marine fish hatchery currently under construction. Genetic markers used to differentiate “populations” of seatrout in Texas have been shown to exist in Mississippi seatrout, but detailed sampling and analyses are currently incomplete.

Objective 4: Develop Culture Technology:

Workplan summary:
Typically seatrout are cultured by introducing pre-feeding larvae into brackish water ponds containing wild, mixed zooplankton. In coastal Mississippi, which is estuarine, pond culture is not feasible for a variety of reasons including the highly variable salinities, the lack of available space, and the shallow water table. Thus, our program has focused on developing intensive tank culture that produces a result comparable to extensive culture.

Activity:
In the second half of 2006, 2 tanks (approximately 20 fish each in a 1:1 sex ratio) produced over 18 million eggs over a 2 month period. Three batches of those eggs (approximately 360,000 each) were stocked into incubators at 1/ml and hatched. Resulting larvae were stocked at 10/liter into a series of six 1500-liter larval-rearing tanks. Larval rearing tanks initially ran static with a background of 50,000 cells Isochrysis galbana/liter. Enriched ss-rotifers and laboratory-cultured Acartia tonsa nauplii were introduced on day-2 post-hatch. On day 5-7 (depending on the growth rate), larvae were transitioned onto enriched Artemia nauplii and recirculation was started. Concurrently with the transition to Artemia, dry food was introduced. As larvae grew, the pellet size and proportion of dry food was adjusted. By day 12 post-hatch, Artemia were discontinued. On day 25 post-hatch, tanks were harvested and larvae were counted and transferred into a growout facility at densities determined by the number of surviving fish. At approximately day 75 post-hatch, juveniles were harvested for tagging and release.

Through 24 days, survival among the 3 batches averaged 18.33%. Larvae averaged 27 mm total length and 157g wet weight, but were variable among batches. A total of approximately 40,000 day-25 fish were produced. Survival during growout for 2 batches averaged 74% at approximately 75 days post-hatch. Juveniles averaged 85.7 mm and 5.97g, but were quite variable among batches at approximately day-75 post-hatch. Approximately 21,000 day-75 fish were produced in the first two batches (batch 3 is ongoing).

Objective 5: Manage Disease and Health:

Workplan summary:
Our broodstock consists of locally caught wild animals treated and quarantined for at least 30 days to remove dangerous ectoparasites that pose a danger to long-term maintenance in closed systems. Briefly, fish are freshwater dipped, treated with praziquantel, and quarantined for approximately 30 days during which time they are transitioned to frozen food and further treated with formalin to ensure the absence of dangerous ectoparasites. Suspicious symptoms are investigated and treatments administered. After quarantine, the fish enter the maturation system where they are cycled on a temperature and photoperiod regimen to induce spawning.

During larviculture, regular gross, histological, and microbiological examinations document the health of the fish. Treatments are administered only as necessary to preserve the stock. Before release, a sample is examined by a certified veterinarian and a health certificate which details the history of the stock is produced and submitted to the agency responsible for permitting the release. The goal is not to produce a disease-free stock, but rather to produce a stock which poses no additional risk to the receiving population.

Activity:
No disease agents were detected and there were no unexplained mortalities. Pre-release veterinary examination detected no health problems; the fish were certified as fit for release.

Objective 6: Describe Life History Patterns and Ecological Interactions:

Workplan summary:
Potential release sites will be monitored before, during, and after release to establish the parameters of the wild population and survival and relative contribution of the released fish. Release sites or methods will be modified as necessary to maximize the success of releases.

Activity:
Two release sites in the vicinity of GCRL and within the area from which the broodstock were collected were chosen based on data from the GCRL Fisheries Monitoring Program and personal observations of staff. Wild seatrout of the approximate size of cultured fish were caught at one of the release sites in the weeks prior to the release.

Objective 7: Identify Released Hatchery Fish:

Workplan summary:
All seatrout released in Mississippi will be coded-wire tagged. Some subset of the fish will be additionally tagged using elastomers or other externally visible tags to address experimental issues such as the effect of site of release, size at release, release method, or time of release. Acoustic tags will be employed on a small subset of cultured fish and wild fish to examine movement, behavior, and residence patterns.

Activity:
In late October and early November, over 21,000 seatrout were implanted with coded-wire tags. This constituted the first ever use of coded-wire tags in spotted seatrout. Lee Blankenship of Northwest Marine Technologies, Inc. assisted with the operation. After examining a wild seatrout, Mr. Blankenship recommended the cheek as the site for tag implantation. Two size groups of fish were tagged ­ one group was approximately 90mm total length and the other was approximately 70mm total length. Initial evaluations indicate a higher than expected tag loss (approximately 20%) over the first few months post-tagging.

Objective 8: Optimize Release Strategies:

Workplan summary:
All seatrout released in pilot studies in Mississippi will be coded-wire tagged. Some subset of the fish will be additionally tagged using elastomers or other externally visible tags to address experimental issues such as the effect of site of release, size at release, release method, or time of release. Acoustic tags will be employed on a small subset of cultured fish and wild fish to examine movement, behavior, and residence patterns.

Activity:
Releases occurred at 2 sites in the vicinity of the Gulf Coast Research Laboratory to assess potential differences in suitability among sites. Approximately equal numbers of 2 size classes were released at each site to assess the effect of size-at-release.

Post-release sampling continues.

Objective 9: Conduct Economic Analysis:
No activities planned.

Objective 10: Develop Adaptive Management Strategies:

Workplan summary:
Data from the monitoring of experimental releases will guide the adaptation of subsequent experimental plans.

Activity:
Future releases will be designed based on the incoming results.

Objective 11: Communicate Results and Network Stock Enhancement Researchers & Managers:

Workplan summary:
The 3rd International Symposium on Stock Enhancement and Sea Ranching will be held September 18-21 in Seattle. SCORE scientists comprise the majority of members on the Steering Committee for that conference; thus, the SCORE consortium is using the opportunity afforded through the 3rd ISSESR to hasten the transfer of SCORE technology and SCORE research strategies to the rest of the USA and the to the international research community.

Activity:
A poster entitled “Developing the technology for intensive rearing of spotted seatrout Cynoscion nebulosus for stock enhancement” was presented at the 3rd International Symposium on Stock Enhancement and Sea Ranching 18-21 September in Seattle, WA.