Associations between surficial sediments and groundfish distributions in the Gulf of Maine-Georges Bank region

The delineation of essential fish habitat is an important element of contemporary fisheries management. Although local-scale species-habitat relationships have been established for some managed species, we lack an understanding of these associations at the synoptic spatial scales on which fish populations and their associated fisheries operate. Interest in habitat delineations has been elevated further by an increased awareness of ongoing habitat degradation caused by mobile fishing gears and by the advancement of spatial management tools. Here we examine the associations between surficial sediment grain size and groundfish distributions in the Gulf of Maine-Georges Bank region. The mean abundances for 58 demersal fish species were determined for a spatial cell grid (185.2 km(2) per cell), which was subsequently joined to a spatially referenced sediment database in a geographical information systems environment. Multivariate statistical methods were then used to examine how fish distribution and abundance varied with substrate grain size. Of the 58 species examined, 12 were consistently associated with particular substrate types. Atlantic cod Gadus morhua, longhorn sculpin Myoxocephalus octodecemspinosus, sea raven Hemitripterus americanus, and winter flounder Pseudopleuronectes americanus were consistently abundant in large-grained substrate types, whereas white hake Urophycis tennis, goosefish Lophius americanus, red hake U. chuss, silver hake Merluccius bilinearis, witch flounder Glyptocephalus cynoglossus, and American plaice Hippoglossoides platessoides were consistently abundant in fine-grained substrates. Little skate Leucoraja erinacea was most abundant in sediments of intermediate grain size. Although broadly distributed, spring dogfish Squalus acanthias consistently distinguished assemblages in fine-grained sediments. Given that we were able to detect even weak associations and that these relationships were consistent with local-scale studies, we recommend using these relationships to further refine essential fish habitat and that they be given more weight in this and similar temperate ecosystems.