FOODS OF THE GULF STURGEON IN THE SUWANNEE RIVER, FLORIDA

Soft-bodied annelids, arthropods, and occasionally globular molluscs w ere primary foods of the threatened Gulf sturgeon Acipenser oxyrinchus desotoi collected from the mouth upriver to kilometer 221 of the Suwa nnee River, Florida, in 1988-1990. In spring, large subadults and adul ts that immigrated from the estuary had fed primarily on lancelets, br achiopods, amphipods and other crustaceans, polychaetes, and gastropod s. Small Gulf sturgeons that remained near the mouth of the river duri ng spring fed on epibenthic and hyperbenthic amphipods and grass shrim p and on isopods, oligochaetes, polychaetes, and chironomid and cerato pogonid larvae found in the intertidal zone. Subadults of more than 5 kg and adults in the freshwater middle river reaches between km 55 and 221 essentially fasted during the summer and fall. Gulf sturgeons in the Suwannee River were indifferent to abundant potential freshwater f oods and apparently had stored sufficient nutrient reserves while in t he estuary. A presumably young-of-year or year-old Gulf sturgeon captu red in summer at the most upriver site (km 221) had fed on aquatic ins ects and oligochaetes. Most Gulf sturgeons of all sizes had ingested d etritus OT biofilm.