NATURALLY-OCCURRING THIAMINE-DEFICIENCY CAUSING REPRODUCTIVE FAILURE IN FINGER-LAKES ATLANTIC SALMON AND GREAT-LAKES LAKE TROUT

A maternally transmitted, noninfectious disease known as the Cayuga sy ndrome caused 100% mortality in larval offspring of wild-caught landlo cked Atlantic salmon Salmo salar from several of New York's Finger Lak es. Survival of lake trout Salvelinus namaycush from Lakes Erie and On tario was also impaired, but not until yolk absorption was nearly comp lete; moreover, mortality was greatly reduced relative to that of the salmon (range: 5-87%). Tissue concentrations of thiamine hydrochloride were severely reduced in these salmonid fish relative to unaffected c ontrol stocks. Afflicted Atlantic salmon treated with thiamine by yolk -sac injection or by bath immersion recovered completely from the Cayu ga syndrome, as evidenced by the quantified reversal of abnormal swimm ing behaviors only 2 d after treatment and by the excellent survival ( >95%) of the treated Atlantic salmon through 1,5 months of feeding. Th ese data represent the first evidence of a vitamin deficiency causing the complete reproductive failure of an animal population in nature. T hese lethal vitamin deficiencies are presumably caused by a diet of al ewives Alosa pseudoharengus, nonnative forage fishes of the herring fa mily that exhibit high thiaminase activity.