The Structures of the Demersal Fish Communities of New Bedford and Gloucester Harbors, Two Massachusetts Urban Estuaries

We sampled the inshore fish communities of New Bedford and Gloucester harbors synoptically using identical gear for 12 months during 1998–1999. Although the 2 harbors are only 110 km apart, they are separated by Cape Cod, which is the transition between the southern New England (New Bedford) and the Gulf of Maine (Gloucester) biogeographic regions. The 2 fish communities were 69% dissimilar from each other using the Bray–Curtis dissimilarity index (B–C). Stenotomus chrysops (Scup) composed 80% of the catch in New Bedford Harbor, did not occur in Gloucester Harbor, and contributed 7.40% to the total dissimilarity between the harbors. B–C identified 2 seasonal groups in the New Bedford Harbor fish community: May–October and November–April. Leucoraja spp. (skates) comprised the most numerous taxon captured in Gloucester Harbor, accounting for 24.90% of the total catch followed by Pseudopleuronectes americanus (Winter Flounder; 24.16%), and Gadus morhua (Atlantic Cod; 22.52%). These taxa contributed 7.23%, 3.88%, and 6.16% respectively to the total dissimilarity between harbors. B–C identified 4 seasonal groups in Gloucester Harbor: January, February and March, April and May, and June–December. These data provide an important description of the fish communities in the 2 harbors in different biogeographic regions at the end of the 20th century. We expect differences between the communities to decrease with increasing water temperature due to climate change.