The distribution of nearshore fishes in kelp and eelgrass communities in Prince William Sound, Alaska: associations with vegetation and physical habitat characteristics

The nearshore (less than 20 m depth) demersal fish community in Prince Will iam Sound, Alaska, is dominated by Pacific cod, Gadus macrocephalus, prickl ebacks (mostly Arctic shanny Stichaeus punctatus), gunnels (mostly crescent gunnels Pholis laeta), a variety of greenlings (Hexagrammidae) and sculpin s (Cottidae). During summer, the spatial distribution of fishes, over scale s of 100's of m to 10's of km, varied by habitats characterized by differen t vegetation types. Juvenile Pacific cod and greenlings were numerically do minant in eelgrass, Zostera marina, beds. Pricklebacks and sculpins were do minant in areas with an understory of the kelps Agarum cribrosum and Lamina ria saccharina. Greenlings and sculpins were the most abundant demersal fis hes in more exposed sites with a canopy of Nereocystis luetkeana and an und erstory of L. bongardiana. Measured habitat variables, including vegetation type, slope, vegetation biomass, and substratum type, explained a signific ant proportion of the variation in the presence or absence of most fishes. The relative importance of different habitat characteristics varied between taxonomic groups of fishes. Vegetation type explained a significant propor tion of variation for cod, rockfishes, and ronquils. Juvenile cod were clos ely associated with eelgrass, while rockfish and ronquils were associated w ith kelps. Pricklebacks and rockfishes were more frequently observed on ste eply sloped shorelines, while ronquils were more often found at sites with higher biomass of vegetation. Within A. cribrosum habitats, more greenlings and sculpins were present at sites where algal biomass was higher. Also, s culpins were more abundant in deeper water and gunnels were more abundant i n shallow water within this habitat. These associations may not have been c ausative. However, evidence suggests that some differences between fish com munities in eelgrass and Agarum beds may have been causally related to vege tation characteristics. The possible roles of different vegetation types as refugia from predators or as sources of prey are discussed.