2003 Research Objectives

• Determine how effective our beam trawl is and, if necessary, to modify it to increase its likelihood of catching small juvenile flounder.
  
  
• Test the predictive capabilities of the HSI models developed in 2002 through in-situ experiments. In this work, we will test growth and survival at 5 geographically separate locations. Two of these will be the locations that the HSI modeling predicted as “best” in the Great Bay Estuary, and 2 will be locations the modeling predicted as “worst” in the Great Bay Estuary. The fifth location will be in the Hampton-Seabrook estuary at the proposed pilot-scale release location. Our prediction is that the fish held in areas with high HSI values will display good growth and survival relative to those in areas with low HSI values, and thereby confirm the habitat modeling approach.
  
  
• Two stress physiology experiments will be undertaken. The first seeks to quantify physiological stress associated with tagging, and to determine whether physiological differences exist in winter flounder juveniles when tagged with elastomer tags and coded wire tags. A second experiment will measure physiological differences in cultured winter flounder during and after transportation from the hatchery to the release site, and also determine if stocking density during transport affects stress physiology.
  
  
• We intend to release 10,000 juvenile winter flounder in August 2003. This experimental release will allow us to: 1) estimate the mortality rate of released fish, and compare it to wild fish; 2) estimate the growth rate of released fish, and compare it to wild fish; 3) describe the diet of released fish, and compare it to wild fish; 4) study the movements of released fish, and compare them to wild fish; and 5) gain insights about the carrying capacity of the release location.
  
  
• Studies have shown that sexual differentiation, and therefore male:female sex ratio, in some flatfish species can be influenced by juvenile incubation temperature. This also may be true for winter flounder, whose juveniles are quite eurythermal, but sexual differentiation and the sex ratio of cultured fish have never been investigated. This is significant because the sex ratio of fish used in stock enhancement programs can affect the wild population. Because the sex ratio of cultured winter flounder, and the factors that may influence it, are completely unknown, and because the sex ratio of stocked fish is fundamentally important, we intend to study sexual differentiation and cultured fish sex ratio as part of this study.