MEPS 428:201-217 (2011)  -  DOI: https://doi.org/10.3354/meps09028

ABSTRACT: Small demersal fishes were collected along the central Oregon coast using a shrimp trawl with small-mesh liner. The trawl was deployed bimonthly in 1989 along 3 transects and along a single transect in March 1989 to 1994. Forty species, 19 of which are not commercially important and rarely reported in other studies, occurred in >5% of the samples. Species assemblages were structured primarily by depth, with mid-shelf stations dominated by flatfishes; on the outer shelf and slope, gadids, scorpaenids, osmerids, and zoarcids were also important. Additionally, 4 out of 5 identified station groups were more closely associated with a single season. Seasonal assemblage structure included a broad range of species whose distributions shifted inshore in summer. This phenomenon, previously described for only a few species off Oregon, further accentuated the correlation of assemblages with depth. Seasonal shifts in distributions appeared to be a function of juvenile settlement and ontogenetic changes in nursery habitat and of seasonal inshore-offshore movements of individuals of many sizes, which indicated that sediment type was not the only feature important in habitat selection. March assemblages were weakly structured by interannual differences, in spite of environmental conditions ranging from the cold La Niña of 1989 to the warm El Niño of 1992. The largest annual differences were among short-lived species and likely reflected differences in recruitment. This study targeted smaller fish than are collected in most bottom trawl surveys and illustrates the importance of seasonal changes in habitat for smaller fish and the value of understanding all life stages in a demersal fish community.

KEY WORDS: Fish communities · Demersal habitat · Size · Density · Diversity · Depth · Oregon Coast