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American shad:

Juvenile emigration representation and timing: We compared hatch date distributions of pre-migrant juvenile shad collected at several locations within the Connecticut River to hatch date distributions of emigrating juvenile shad at two hydroelectric dams in the lower Connecticut River. We also examined daily growth rates of juveniles by measuring otolith ring spacing from shad collected throughout the summer and fall. A University of Massachusetts M.S. student, Matthew O'Donnell, led this project.

Migratory energetics of American shad (Alosa sapidissima), an iteroparous anadromous fish: Working with Ted Castro-Santos, we used an individual-based modeling exercise, in which migratory American shad ascend the Connecticut River, spawn, and return to the marine environment.  We use an integrative approach, incorporating data and assumptions of bioenergetics, reproductive biology, and behavior to improve our understanding of the effects of migratory delays and thermal alterations on distribution, spawning success, and survival.

Atlantic salmon:

Climate change: Because most climate change effects on stream fish are likely to operate through changes in stream temperature and flow and our models can relate effects of these environmental variables to population persistence, we have also been funded to extend our salmon model to incorporate climate change scenarios. This is a collaborative project with the Maine WRD office and other WRD offices. PhD student Krzysztof Sakrejda is leading this project.

Effects of shelter availability on survival: Working with Drs. Anders Finstad and Sigurd Einum, we are evaluating the effects of shelter availability on Atlantic salmon survival. Our Norwegian colleagues have developed a technique to non-invasively estimate shelter availability. In 2007, they assayed our sample area. We will relate survival of salmon to local shelter availability and will compare results from our study stream, which appears to have lower shelter availability compared to Norwegian streams, to results from Norwegian streams.

Food habits of Atlantic salmon: None of the existing models of Atlantic salmon growth include food availability and prey choice. During two years, we sampled food habits of fish in the West Brook using gastric lavage of tagged fish. Seasonal food availability (drift and benthos) were sampled and compared to prey choice. Prey choice of Atlantic salmon was found to be opportunistic, but salmon gut contents did not always reflect prey densities. Gut content masses did closely mirror growth, suggesting a behavior control of feeding which may be related to sheltering in the summer. A University of Massachusetts M.S. student, Melissa Grader, led this project.

Predation on stocked fry: A large source of mortality, especially for fish rapidly introduced into a novel environment, can be predation mortality. We evaluated the proportion of stocked fry that were consumed by predators on four rivers to identify sources of early mortality. Depending on larger trout and salmon densities, from 18 to 55% of the stocked fry were eaten within the first two days following stocking. Stocking agencies have incorporated these findings into stocking strategies. Nathan Henderson, an M.S. student, conducted this study.

Phenotypic variation among U.S. Atlantic salmon stocks: Using laboratory common environment studies, we evaluated phenotypic variation among US Atlantic salmon stocks. Results indicated variation among stocks in size and growth during egg/alevin stages and in smolt age, but very little variation during the fry and parr stages. Populations with more hatchery supplementation, which has relied primarily on stocking age-1+ smolts in the past, demonstrated a greater proportion of age-1+ smolts than populations which have experienced less supplementation. This study identified the extent of variation among US Atlantic salmon populations and appears to have found a link between hatchery practices and population-specific life history expression. Mariska Obedzinski, an M.S. student, conducted this study.

Effects of tagging on growth and survival: Handling and tagging fish could influence growth and survival. To test the effect of PIT tagging and electrofishing on fish, we conducted a series of laboratory studies. Results indicated that there may be short-term (month) effects on growth from electrofishing, but no effects on survival or growth from tagging. We also determined that tag loss was very low (<1%).