Alligator mississippiensis (American Alligators) demonstrated low hatchrate
success and increased adult mortality on Lake Griffin, FL, between 1998 and
2003. Dying Lake Griffin alligators with symptoms of poor motor coordination were
reported to show specific neurological impairment and brain lesions. Similar lesions
were documented in salmonines that consumed clupeids with high thiaminase levels.
Therefore, we investigated the diet of Lake Griffin alligators and compared it with
alligator diets from two lakes that exhibited relatively low levels of unexplained
alligator mortality to see if consumption of Dorosoma cepedianum (gizzard shad)
could be correlated with patterns of mortality. Shad in both lakes Griffin and Apopka
had high levels of thiaminase and Lake Apopka alligators were consuming greater
amounts of shad relative to Lake Griffin without showing mortality rates similar to
Lake Griffin alligators. Therefore, a relationship between shad consumption alone
and alligator mortality is not supported
