28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Thiamine Deficiency Effect On Health And Well Being Of Great Lakes Salmonids Dale C. Honeyfield1, John D. Fitzsimons2, Don E.Tillitt3, Jim L. Zajicek3,  Scott B. Brown4, Perran Ross5, Timothy S. Gross5,6, Maria S. Sepúlveda5,6 1Northern Appalachian Research Laboratory, USGS, Wellsboro, PA, 16901; 2Department of Fisheries & Oceans, Burlington, ON, Canada  L7R 4A6; 3Columbia Environmental Research Center, USGS, Columbia, MO  65201; 4Environment Canada, Burlington, ON, Canada. L7R 4A6; 5University of Florida, Gainesville, FL,  32610; 6Florida Integrated Science Centers, USGS, Gainesville, FL  32653 Early life stage mortality in salmonids in the Laurentian Great Lakes and NY Finger Lakes is a significant problem.  The mortality of swim-up fry dying from early mortality syndrome (EMS), a non-infectious disease, ranges from 0 to 100% depending upon the lake, the salmonid species, stock within a species, and year class.   The syndrome is characterized by lack of vitamin B1 (thiamine).  Adult salmonids feeding on prey species (alewife, rainbow smelt) containing thiaminase produce eggs low in thiamine and fry die between hatch and swim-up.  Thiamine treatment of eggs or fry is effective but it is only practical in species that migrate to weirs where eggs are collected and reared in the hatchery.  Since lake trout eggs are not collected, thiamine treatment is not an option.  Characteristic thiamine deficiency brain lesions have been observed in lake trout that survived overt mortality and in Atlantic salmon from the Baltic Sea.  In the Baltic region the malady is called M74. Recent data suggests that thiamine deficiency is affecting neural function (visual acuity).   Both predator avoidance and prey capture were found to be impaired in lake trout fry with low thiamine. In addition we have evidence that adult coho salmon, steelhead, and lake trout are dying as a result of thiamine deficiency.  This has implication on maintaining adequate numbers of adult spawners.  Thiamine deficiency is linked to adult salmonids foraging on thiaminase containing prey, alewife and rainbow smelt.  Thiaminase in alewives is highly variable.  The cause of the variability is under investigation.  Naturally occurring thiamine deficiency appears to be occurring in Florida alligators foraging on gizzard shad.  Overall the data suggest that thiamine deficiency in wild aquatic top predators significantly impacts sustainable reproduction and probably is a sign of a dysfunctional ecosystem. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page