EFFECTS OF BOTTOM FISHING ON THE BENTHIC MEGAFAUNA OF GEORGES BANK

This study addresses ongoing concerns over the effects of mobile fishi ng gear on benthic communities. Using side-scan sonar, bottom photogra phs and fishing records, we identified a set of disturbed and undistur bed sites on the gravel pavement area of northern Georges Bank in the northwest Atlantic. Replicate samples of the megafauna were collected with a 1 m Naturalists' dredge on 2 cruises in 1994. Compared with the disturbed sites, the undisturbed sites had higher numbers of organism s, biomass, species richness and species diversity; evenness was highe r at the disturbed sites. Undisturbed sites were characterized by an a bundance of busby epifaunal taxa (bryozoans, hydroids, worm tubes) tha t provide a complex habitat for shrimps, polychaetes, brittle stars, m ussels and small fish. Disturbed sites were dominated by larger, hard- shelled molluscs, and scavenging crabs and echinoderms. Many of the me gafaunal species in our samples have also been identified in stomach c ontents of demersal fish on Georges Bank; the abundances of at least s ome of these species were reduced at the disturbed sites.