May 28, 2002

A. Brief Project Overview:
The Science Consortium For Ocean Replenishment And Enhancement (SCORE) is a new science-based approach to hatchery-based rebuilding (enhancement) of marine fish stocks. SCORE scientists are conducting research to resolve critical uncertainties about the effectiveness of culture-based marine stock enhancement as a fishery management tool. It is anticipated that significant progress will be made in the next five years, 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 will partner 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 will provide the cadre of citizens needed to support and expand enhancement as a fishery management strategy. SCORE scientists envision that much of 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 the marine enhancement concept, 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, SCORE scientists will conduct key experiments to resolve critical uncertainties about how to conduct and control the biological, ecological, and economic effectiveness of stock 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.

SCORE research commenced in the summer of 2001. This interim report covers progress made during the period January 1, 2002 through June 30, 2002.

B. Project Accomplishments:

a. Tasks scheduled for this period
i Develop snook broodstock diets
ii. Develop snook spawning induction
iii. Develop snook larval feeding
iv. Conduct snook trophic analysis
v. Conduct habitat and predation study with snook
vi. Develop habitat/release model for winter flounder
vii. Develop marine fish culture policy (Washington)
viii. Culture Technique for Enhancement of Depleted Yelloweye Rockfish and True Cod
ix. Ecology and early habitat choice of post-larval lingcod
x. Collect economic data (all species)
xi. Develop risk/benefit models (all species)

b. Tasks accomplished this period:
Develop snook broodstock diets (Primary responsibility: Mote Marine Laboratory)
No progress has been made on this objective during this reporting period. The results of our 2001 production season along with space limitations caused us to postpone the work on snook Broodstock diets until fall/winter 2002/2003.

ii. Develop snook spawning induction (Primary responsibility: Mote Marine Laboratory
This work is closely related to the broodstock diet objective and is postponed until fall/winter 2002/2003. A no-cost extension of the project has been requested to provide the additional time needed to complete both Tasks i and ii.

iii. Develop snook larval feeding (Primary responsibility: Mote Marine Laboratory)
2001/2002 Snook Production Efforts
During this reporting period, our efforts were focused on growing snook fingerlings for tag and release experiments scheduled for April/May 2002. The snook continued to show good growth through the second size grading. Cannibalism had reduced the number of fish in culture and large numbers of fish began showing signs of lordosis (a spinal deformity highly correlated with the absence of air bladder formation). Potential causes of lordosis include buildup of surface film in larval rearing tanks resulting from addition of live feeds and nutritional deficiencies in both the larval rearing and nursery I phases. During the 2001/2002 production season, fish with lordosis were removed from the nursery tanks during regular size gradings (every 30-45 days). At the end of the production season a total of 2477 juvenile snook were used for tag and release experiments. Research and production trials in the 2002/2003 production season will focus on reducing cannibalism during nursery I and reducing the incidence of lordosis in larval rearing.

We developed a manual on the snook and live feeds culture protocols that were used in the 2001/2002 production season. This manual is being revised during the 2002/2003 production season. A presentation on the larval culture methods for common snook was given at the World Aquaculture 2002 meeting. A copy of the abstract is included in the Appendix to this report.

2002/2003 Snook Production Efforts
The snook larval rearing and nursery production systems at Mote Marine Lab were redesigned to include better filtration components. Cartridge filters were replaced with bead filters for both particle and biofiltration. Nine new tanks were installed in the hatchery and will be used for the 2002/2003 production efforts. Protein skimmers, sprayers and surface skimmers were added to all tanks to remove the surface film during larval rearing.

vi. Conduct snook trophic analysis (Primary responsibility: Mote Marine Laboratory
No work was planned for this objective during this reporting period. Subsequent studies will evaluate a broader size range of juveniles and begin to look at sub-adult and adult snook feeding patterns.

v. Conduct habitat and predation study with snook (Primary responsibility: Mote Marine Laboratory
At our current stage of snook enhancement research and development, we are conducting research to define optimal release strategies needed to document snook enhancement potential. A major focus of those studies now is determining effects of microhabitat on dispersal and survival of hatchery snook released into nursery habitats in Sarasota Bay, Florida. Predation studies will follow, as we are now designing new experiments to study density-dependent effects on dispersal and predation rate.

DEPLETION/REMOVAL STUDIES.
In the snook stock enhancement program we are addressing some of the ‘issues of the day’ such as quantifying the carrying capacity of the estuaries near Sarasota - - how many stocked snook can these systems actually hold before we see negative impacts on the wild fish and the associated ecosystem? We performed “depletion/removal” studies, where a representative portion of the system is blocked off and all fish are subsequently removed with seines from the area until the population of snook and prey species within the area are known. Nine seine pulls were performed in the blocked area. A plot of the catch size over the trials showed a declining catch rate until no fish were captured These estimates can then be interpolated to predict actual populations of the various species within the overall habitat. These depletion studies were performed in January and February, 2002, in North Creek, Catfish Creek, Bowlees Creek, and Buttonwood harbor. Once these representative areas are quantified, this knowledge can be used to retroactively determine relative abundance patterns at our study sites that were quantitatively sampled over the past 4 years. Depletion-removal sampling also allowed us to estimate the catch efficiency of the first net set within a given area. These studies are assisting us in designing future releases.

TEST OF DENSITY-DEPENDENCY EFFECTS WITH HATCHERY-REARED JUVENILE SNOOK RELEASED IN CRITICAL NURSERY HABITATS - EXPERIMENTAL DESIGN
The primary emphasis of the 2002 snook experimental releases has been to identify potential density-dependent effects in juvenile snook populations. The basic theory behind density-dependence is that population size is controlled by intra-specific competition or predation for a limited resource. Therefore, interspecific competition or predation limits further expansion of the population. In many species, a density-dependent mechanism may only operate within a specific age category, such as among juveniles. The common snook exhibits signs of density-dependency, such as being piscivorus and cannibalistic. As part of a responsible approach toward the pilot studies of stock enhancement with juvenile snook, the potential for density-dependence with juvenile snook must be investigated. Since 1997, hatchery-release-recapture studies have focused on effects of release strategies on survival and growth of cultured snook. We are now focusing our attention on the interactive effects of hatchery released fish on wild snook populations.

In May, 2002, we began tests of density-dependent survival using hatchery releases of juvenile snook into nursery habitats in Sarasota Bay. Before releases occurred, estimates of age-0 and age-1 abundances of snook in the nursery habitats were necessary. Four creeks harboring nursery habitats were selected for this experiment: South Creek, North Creek, Bowlees Creek, and Whitaker Bayou. Sampling occurred in all creeks to determine snook abundances. Because juvenile snook abundance in these areas is generally associated with shoreline habitat, sampling effort was related to total shoreline distance. Aerial photographs were used to obtain total shoreline habitat within the creeks and every third 100' section of the shoreline was sampled within these nursery habitats (the 4 creeks). A 220 foot seine was used as the standard sampling gear, and on open shorelines (i.e. shorelines with no opposite banks within 70' of the shore) the net was deployed 70' offshore. Immediately following this deployment, 70' of the net was pulled to the shore while the other end was arched toward the shore approximately 100' away. Thus, 100' of shoreline was sampled. In stream and canal habitats, both shores were sampled, and again, 70' of the net was used to block off the lower half of the sample section while the remaining net was pulled down one of the shorelines approximately 100' and arched across to the opposite shore. With this method, roughly every third 100' section of shoreline habitat within the creek was sampled. In many cases shoreline habitat was not sampled because of logistical difficulties, however. Pre-Release April 2002 Sampling The total net sets per creek, estimated shoreline distance, and snook abundance from the April 2002 samples are shown in Table 1.

All captured snook (hatchery and wild) were tagged with VIE tags in the caudal fins and with sequential CWTs before they were released. Different VIE colors were used to identify the creek where the snook were captured, and fin location to identify snook recaptured multiple times.

Age 0 and age-1 snook abundance were estimated in the following way: total age-0 snook = x * ts/100

where, x = mean catch of age-0 snook within a creek ts = total shoreline habitat (in feet)

May 2002 Tagging and Release
In May, 2002, 2477 juvenile hatchery-reared snook were tagged and released into creeks and estuaries that feed Sarasota Bay (Table 1). Tagging activities occurred on May 14-15, 2002 at the Mote Marine Laboratory Aquaculture Facility. All released snook were tagged with a coded-wire tag (CWT) and a visible implant elastomer (VIE) tag. CWTs were injected into the left cheek muscle with automatic Mark IV CWT injectors (produced by Northwest Marine Technology, Inc.) owned by the State of Florida’s Fish and Wildlife Conservation Commission’s Port Manatee Stock Enhancement Research Facility (SERF). John Ransier from the SERF facility also assisted in the snook tagging project at the Mote Marine Lab Aquaculture Facility. CWTs identified the experimental treatments outlined above, as well as general size class (smalls: 70-125mm FL; medium: 125-160mm FL; and large: 165-270mm FL). Fluorescent red VIE tags (Northwest Marine Technology, Inc.) were injected into the caudal fins of each snook for release. This tag provided a visible identification of the released fish as hatchery reared snook.

Tagged juvenile hatchery snook were then returned to their tanks and held for 1 week to recover from the tagging process and rest until the releases. Tank salinities ranged from 3 ppt - 6 ppt and water temperature between 26 - 30o C.

Health certification checks were performed by a USDA Certified Veterinarian on sub-sampled snook from each source group prior to tagging. Upon receiving approval for release, the tagged juvenile snook were released into four creeks in the Sarasota area, as described in the table below. The juvenile snook were transported in hatchery water in tanks with trucks and boats. To improve post-release survival rates all released snook were stocked into predator-free acclimation “pens” located within the creeks and held for 3 days. These activities were based on results from experiments performed in 2000 where snook were acclimated for 3 days in situ . Follow up sampling in the creeks where snook were acclimated showed that recapture rates were 2x greater for snook that were acclimated than for snook released directly into the wild. This effect occurred immediately (within 30 days after the release. Samples taken 2-4 months after release, and 9 months after release again showed that recapture rates were twice as high for acclimated fish compared to non acclimated fish). Therefore, on May 23, 2002 all snook were released from the acclimation pens into the wild.

To determine initial tag retention rates, sub-samples of tagged fish were taken from each release group 2-3 hours before the release occurred. As a result, tag retention was checked 6 days after tagging. All fish from each release group was checked for the presence of a CWT with a CWT detector and each fish was also checked visually for the presence of a VIE. Total counts were taken from each tank to determine post-tagging mortality rates. Retention rates from the 2002 tagging activities with juvenile snook were excellent. CWT rates averaged 99.5% retention (from 14 groups with an average of 84 fish/group), and VIE retention was 100% 6 days after tagging. Release numbers were then calculated for each creek using the available hatchery snook (~ 2800 snook). Because Whitaker Bayou and Bowlees Creek were estimated to have lower age-0 snook populations, they were chosen for “high density” releases and North Creek and South Creek were chosen for “low density” releases. Pre-release estimates of age-0 snook in the creeks are shown in Table 2.

Post-release sampling will occur in June, August, October, December, 2002, and January 2003, and results from the follow up sampling will be reported as they progress.

ADAPTING TAG TECHNOLOGY TOWARD STOCK ENHANCEMENT OF SNOOK IN FLORIDA
Development of tag technology with juvenile snook has been an ongoing research goal. During January - June 2002 much of this research has matured and will be presented in the final report for this fiscal year. Primarily several significant advances in adapting appropriate tags toward juvenile snook are reported:

$ - Coded Wire Tags (CWT): CWTs implanted in the cheek muscle resulted in high mean retention rates achieved in 1999, 2000, and 2002 large-scale tagging operations (97.15%, 95.43% and 99.6% respectively). Generally, tag retention was influenced by tagger experience, the tagger’s concentration level, and to some extent, fish condition. CWT tagging rates for the cheek muscle were between 400-800 fish per hour depending upon tagger experience. Fish size affected retention, where larger snook had higher tag retention than smaller snook. Tagging mortality during the “large-scale” operations was 0.14%-1.55%.

In general, coded-wire tags provide a relatively quick, low cost, and easy tagging approach while having a minimal effect on survival of the tagged fish. Tag retention rates of 94-99% achieved in these studies are acceptable for a large-scale tagging operations. Tagging “free hand” into the cheek muscle is slower than head mold tagging (400-700 fish/hour vs. possibly 800-1200 fish/hour). Retention of CWTs applied free hand were affected by tagger experience and dexterity, the tagger’s concentration level, and to some extent fish condition. Size-at-tagging also had an effect on retention, where the smallest size class was the most difficult to tag and had the poorest retention. Little error was allowed with small fish because there was physically a very small amount muscle tissue to inject the tags into and explains the lower retention and variable retention rates. A careful, focused effort, however, could produce high retention rates for this size class as seen in the 1999 retention results (Figure 3). It is plausible that very small snook (30mm +) could be successfully tagged if the CWTs were to be applied to the nape muscle, or in other body muscles of larger mass. The use of half length CWTs would also improve retention in small fish. The cheek muscle is a useful tagging site in the sizes tested, but snook smaller than 50mm would most likely have insufficient amounts of mussel tissue to retain the tags.

Once developed and refined, head mold tagging may be superior in the context of large-scale operations. The morphology of the nose cartilage area is porous in snook, but careful selection of a target site and an oblique needle approach may have successful results. The variable retention rates among head molds modeled from snook of the same size showed that tag placement varied by head mold and an optimal placement has not yet been found. Directing the CWT injection into the nape muscles shows promise also, but because of the snook’s long head shape a skewed needle approach would be necessary. CWT retention in the caudal peduncle was also high, and we assume that CWTs applied to other muscular regions of the snook such as the dorsal muscles would also result in high retention. The needs of our stock enhancement program, however, dictate that CWTs must be implanted in “disposable” regions of a snook body, such as the head, and not in regions that are more likely to be consumed. The fact that implanted CWTs are not identifiable by fishermen facilitates the need for an additional tag such as the VIE to identify a hatchery fish.

$ - Visible Implant Elastomers (VIE): Overall, long-term VIE retention was highest in the anal fin and caudal fin in juvenile snook. Field and laboratory studies revealed that twelve months after tagging VIE mark retention in the dorsal and ventral lobes of the caudal fin was 76% and 72% compared to 35% 27% and 17% mark retention in the adipose eyelid, nose skin and jaw respectively. The use of multiple marks significantly increased tag presence compared to single marks; eg. three months after tagging, the presence of a VIE tag was found in the caudal fin in 92% of the snook tagged when both tag sites (dorsal and ventral caudal fin lobes) were considered, while only 76% of the snook contained a tag in the dorsal lobe. Another trial revealed similar results: 98% with 2 marks vs. 86% with 1 mark. A third trial was conducted with four marks injected per fish in the caudal fin. This resulted in 95% of the snook retaining a VIE even 16 months after tagging. Injection of multiple marks required very little additional effort and acceptable tagging rates of 200-300 fish per hour were achieved. Multiple marks also improved the overall visibility of the tag. Fish size affected tagging ease and tag retention for VIEs implanted in the caudal fin, anal fin, and nose where small fish had poorer tag retention than large fish.

These small-scale tagging operations with juvenile snook demonstrated that CWTs and VIEs can be used jointly to provide a reliable tagging system - even with complex experimental designs. The use of sequential CWTs allowed hundreds of code groups to be applied to the released fish, and in 2001, unique sequential tags were archived for every fish tagged (to reference individual length and weight data) which represented over 2600 code groups. Additionally, VIE were successfully adapted to snook with reliably high long-term retention rates in the caudal and anal fins. The use of multiple color and body locations with VIEs could be used to externally identify experimental treatments with minimal harm to the fish. As the released snook continue to mature, the ongoing tag recovery program will continue to allow fishermen to participate in data collection efforts of the stocked fish.

vi. Develop habitat/release model for winter flounder (Primary responsibility: University of New Hampshire) Improving Marine Finfish Stock Enhance
ment Programs Through the Use of Habitat Suitability Index Modeling

Objective:
The overall objective of the research is to use Habitat Suitability Index (HSI) modeling to predict appropriate release locations for winter flounder in the Great Bay Estuary of New Hampshire. Habitat variables used in the modeling have included temperature, salinity, depth, substrate type, prey availability, and predator abundance. We originally intended to layer individual variables, as well as the HSI values, in a geographic information system (GIS) to produce habitat maps. Our thought was that such maps would be useful in choosing release locations. Results of the study, which is essentially complete, now suggest that producing GIS maps is an unnecessary step.

Methods and Materials:
To start the study, eight sites were chosen in the Great Bay Estuary system. They were selected because we believed they would represent a gradient in temperature, salinity, and substrate type. All sites were a minimum of 2 kilometers from each other. Sampling of sites occurred monthly. On each sampling date, 2 ten-minute tows were conducted with both a 1-meter beam trawl and a 6-meter otter trawl to determine the spatial and temporal distribution of fishes and potential predators. All species collected have been identified and enumerated, and the lengths and weights of all winter flounder have been measured. Fish were frozen and returned to the lab where stomach content analyses have been performed. All contents have been weighed, and prey taxa have been identified to the lowest possible taxonomic level. To obtain information on prey abundance, benthic cores were also taken at each site. All cores were washed through a 1-mm sieve, and all organisms have been identified to the lowest possible taxonomic level. Temperature at each site was measured once per hour using an Onset HOBO data logger anchored one foot off the substrate at the center of each site. Salinity was measured (refractometer) at the time of sampling, and depth was recorded at the time of each trawl. Substrate information was obtained from two sources; grain size composition from the EPA’s Coastal 2000 project, and sediment organic content from archived data already available.

To gain an understanding of the importance of different prey species, an Index of Relative Importance (IRI) was calculated for each prey item. Eleven prey taxa made up >97% of the diet. For these, we have also examined if, and how, their importance changed with different sized fish (50-100, 101-150, 151-200, 201-250, and 251mm and larger). Three size categories of fish were also used to compare the diets at different sites and different seasons.

The eleven most important prey items were used to characterize the similarity between sites during each season, and the similarity between months at each site. Data were root-root transformed and entered into the Bray-Curtis Similarity equation. Resultant similarity distances were graphed using Cluster Analysis and Multidimensional Scaling to determine how the different sites grouped relative to prey composition and abundance. The composition of each site was graphed over time to see general trends in benthic productivity, and the abundance of each prey item, for all sites combined, was graphed to depict their productivity over time

To examine the temporal and spatial overlap between winter flounder and their potential predators and competitors, we compared the catch-per-unit-effort of winter flounder to those of smooth flounder, green crab, and two species of sand shrimp using ANOVA.

An overall habitat suitability index was determined for each site and month. This was compared to catch per unit effort of winter flounder (# fish per 100 m2) to see if the distribution of fish fit the habitat model. We also compared the catch-per-unit-effort of winter flounder with each variable within the model (ANOVA and ANCOVA) to determine which component(s) may have been driving habitat selection.

Finally, we tested the HSI model predictions with the actual temporal and spatial distribution patterns of the fish to determine the utility of the model.

Results:
Gut contents from 178 winter flounders were examined. Amphipods were the most important dietary item (highest Index of Relative Importance) in all fish < 200mm total length. Fish greater than 200 mm TL had a much more varied diet, suggesting an ontogenetic shift towards more dietary diversity. There was little change in diet over time (no significant differences between sampling months). This was quite surprising given the strong seasonality in the abundance of prey taxa. These results indicates that young winter flounder are quite selective, at least during the months when their preferred taxa are less abundant. There were no significant differences in either the composition or abundance of the prey communities among the different sampling sites.

A Habitat Suitability Index was calculated for each site for each month. Values ranged from 2.2 to 8.4 on a scale of 0-10, with 10 indicating the highest suitability. No sites or months were completely unsuitable (value=0). There were significant differences between sites when all months were combined. Five had low suitability indices (values 3-4.3) while the other 3 had high suitability indices (values >5). There were no significance differences in suitability between months when all sites were combined. Among the most significant of our findings was that there was no statistical relationship between catch-per-unit-effort of flounders and the predicted habitat suitability based on the 4 variables measured (depth, temperature, salinity, substrate type). Among these variables, only salinity was correlated (positively) with catch-per-unit-effort. We also looked at the relationship between the temporal and spatial distribution of winter flounders and 2 of their known predators, green crabs and grass shrimp, and no correlations were found.

Conclusions:
The habitat suitability modeling approach proved useful in identifying release locations for juvenile winter flounder. Of the 8 sites we examined, 3 seemed “better suited” as release locations. We believe, however, that habitat suitability models can be improved. The models we developed were quite simplistic in that we attempted to measure and characterize habitat suitability using just 4 variables. Obviously there a large number of habitat attributes, acting alone and in concert with others, and the modeling effort would probably have been improved by the addition of other variables. Results would also have been better had we caught more fish on which to base the analyses. Our low catch-per-unit-efforts were unexpected and unavoidable, and they were quite low relative to the limited historical data. This suggests that winter flounder are well below their historical carrying capacity, and/or that there has been a fundamental shift in the faunal community in this estuary.

Results from this study have proven quite useful to our winter flounder stock enhancement research program. We now understand what the small fish are eating in nature, we know the temporal and spatial distribution of these prey taxa, as well as their seasonal abundances. We also have the same data for their potential predators. Further, we have identified 3 sites that, at least on the basis of 4 variables, seem to be quite suitable for winter flounder juveniles. We intend to complete the study by conducting in-situ growth and survival trials at the same 8 sites. Our expectation is that results from this study will confirm the habitat modeling approach. Winter flounder juveniles to be used for this are currently being produced.

vii. Develop marine fish culture policy (Primary responsibility: Washington Department of Fish and Wildlife
The Washington Department of Fish and Wildlife (WDFW) has prioritized culture system development of Pacific Cod over releases of lingcod to evaluate ecology, population status and species interactions. Work with genetic structure and habitat preference, however, will proceed as planned for lingcod, although this work will be conducted during 2002 instead of 2001.

A subcontract for work to be done by the University of Washington (UW) is nearing completion. UW scientists will be looking at early life history and ecology of lingcod juveniles, as well as settlement cues, for eventual releases of Lingcod.

viii. Culture Technique for Enhancement of Depleted Yelloweye Rockfish and True Cod (Primary Responsibility: NMFS Northwest Fishery Science Center
Yelloweye rockfish were successfully reared for the first time through the sensitive larval phase by SCORE researchers. Accomplished using methods developed at the Northwest Fisheries Science Center’s aquaculture facilities at its Mukilteo and Manchester Research Stations, this is the first time this species has been reared beyond 30 days.

Yelloweye rockfish stocks are believed to be severely depleted with rebuilding plans that are estimated to take from 40-170 years using current management approaches. The successful culture of larvae of this species is the first step needed to determine if rebuilding can be accomplished in a timelier manner by stock enhancement strategies such as stocking cultured recruits. Funding from SCORE and the National Marine Aquaculture Initiative from the Office of Ocean and Atmospheric Research, NOAA supported this project.

Captive broodstock of Pacific True Cod Established
Fifteen juvenile and adult Pacific true cod were captured to serve as broodstock for the development of culture methods for this species. True cod are severely depleted in Puget Sound, Washington. The capture activity was a collaborative effort between the WDFW and the Northwest Fisheries Science Center. The collection was timed to correspond with the normal spawning season of True Cod in Puget Sound waters with hopes of spawning wild gravid fish, however all the cod captured were either immature or had already spawned. Fish are currently being held at the Manchester site with hopes of spawning next winter.

ix. Ecology and early habitat choice of post-larval lingcod (Primary Responsibility: NMFS Northwest Fishery Science Center)
This research is focused on age-0 lingcod ecology. Studies are being conducted in two areas: 1) Characterization of lingcod habitat use in both space and time, and 2) Otolith-based assessment of planktonic stage length. In the field, subtidal surveys were conducted to examine the benthic aggregations of juvenile lingcod. The survey of juvenile habitat, recorded both the timing of arrival to, and departure from, nearshore habitat and associations with benthic macro algae and other ichthyofauna.

In the second part of this study the changes in otolith structure was examined during the larval period. Lingcod were reared from egg to metamorphosis at the Manchester site. Lingcod otoliths may contain microstructure that allows for measurement of time-to-settlement. Juvenile lingcod undergo a pigment change from silvery herring-like coloration to green mottled coloration, and an abrupt diet change, just prior to settlement. These physiological changes and the stress of settlement may produce a settlement check on their otoliths. During a small pilot study (winter 2001) growth rings were resolved from lingcod otoliths using a Scanning Electron Microscope (SEM). Ring width was consistent with those described as daily rings in other species (i.e. 2-3 :m). By examining the growth rings between hatch and settlement marks a count of planktonic days should be possible. Data for both studies is currently under analysis and will be presented as a Master’s thesis (Jake Gregg, University of Washington) sometime next year.

x. Collect economic data (all species)
No work was conducted during this report period.

xi. Develop risk/benefit models (all species)
No work was conducted during this report period.