The reintroduction of Atlantic salmon into Lake Ontario is a top priority for management agencies and conservation groups. However, these reintroduction efforts have not yet produced a self-sustaining population of Atlantic salmon. One major factor that has been hypothesized to obstruct reintroduction efforts is the high abundance of exotic prey fishes—rainbow smelt and alewife—in Lake Ontario. Unlike historical prey, these introduced species contain high levels of the enzyme thiaminase, and their consumption has been associated with a thiamine deficiency in a variety of Great Lakes salmonids. Working on Atlantic salmon, my lab has previously identified negative effects of dietary thiaminase on traits that include swimming performance and body condition. Importantly, these effects differed among the three Atlantic salmon strains targeted for reintroduction into Lake Ontario, suggesting that strain selection could help mitigate these negative effects. However, some of the most serious effects of thiamine deficiency occur during the reproductive phase, but these effects have never been compared among strains. The research proposed here will quantify the magnitude of the effects of dietary thiaminase on reproduction in Atlantic salmon and compare this effect among the three candidate strains. The specific objectives are to: (1) determine if a high-thiaminase diet affects reproduction in Atlantic salmon, using as metrics the thiamine concentration in milt and eggs, sperm performance, fertilization success and mortality prior to the onset of exogenous feeding; (2) determine whether three populations of Atlantic salmon differ in the effects of dietary thiaminase on the measured reproductive traits; and (3) use these data to assess the importance of dietary thiaminase as an obstacle to the re-establishment of Atlantic salmon in Lake Ontario and the potential for strain selection to overcome this challenge.
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