Can Early Feeding in Lake Trout Fry Ameliorate Thiamine Deficiency?

Recruitment failure of lake trout (Salvelinus namaycush) in the Great Lakes has been attributed to the consumption of alewife (Alosa pseudoharengus) by adult lake trout, eventually leading to Thiamine Deficiency Complex (TDC) in alevins.  TDC results in early mortality and is likely hindering successful restoration. Prior studies found that wild fry begin feeding before yolk-sac absorption but in hatchery-reared fry first feeding does not occur until after yolk-sac absorption. We postulated that wild-hatched alevins could mitigate thiamine deficiency through early feeding on natural prey. Eggs were collected from 53 adult lake trout from Lake Champlain. Upon fertilization each family was split in half; one group was treated with thiamine and the other was untreated.  Eggs were reared until hatching; then each group was split again into fed and unfed groups.  Fry groups were kept under similar conditions; the fed group was fed a mixture of zooplankton daily.  Fry were sampled weekly and thiamine levels will be quantified using HPLC.  If the results show an increase in thiamine in fed fry, wild fry with access to zooplankton may be able to mitigate the effects of low maternal thiamine by early feeding.