PREY SELECTION BY THE HOGCHOKER, TRINECTES MACULATUS (PISCES, SOLEIDAE), ALONG SUMMER SALINITY GRADIENTS IN CHESAPEAKE BAY, USA

We investigated feeding by the hogchoker, Trinectes maculatus (Bloch a nd Schneider), in freshwater, oligohaline, mesohaline, and polyhaline regions of Chesapeake Bay, USA, and examined prey selection in relatio n to food availability. Otter trawling for fish and Van Veen grab samp ling for benthic macrofauna occurred in July and August 1992 and Augus t and September 1993. Hogchokers exhibited both opportunistic and sele ctive feeding patterns along the estuarine salinity gradient in four t ributaries (Potomac, Rappahannock, York, and James Rivers) and in the mainstem Chesapeake Bay. Major prey taxa included annelids, arthropods , and tellinid siphons. In polyhaline habitat, polychaetes dominated b oth the benthos and gut contents numerically and gravimetrically. On t he other hand, oligochaetes were numerically dominant in freshwater/ol igohaline areas but were rarely eaten, perhaps because of their burial depth. Arthropods (mostly amphipods) occurred at most salinities, wer e common in gut contents in low-salinity areas, and were replaced as p rey by larger proportions of polychaetes in polyhaline regimes. Althou gh hogchokers ate tellinid siphons, they rarely consumed whole bivalve s or gastropods. These diet patterns (and especially the importance of siphon nipping) are similar to those of juvenile or small flatfish el sewhere in Europe, Africa, and North America. A size-salinity relation ship for hogchokers occurred along the summer salinity gradient, with smaller fish predominating upstream and larger fish downstream. It was not clear from our data if variation in diet composition reflected ch anges in prey composition along the salinity gradient rather than chan ges in fish size.