Fish Assemblages in Nearshore Habitats of Prince William Sound

We sampled fish at eight locations in western Prince William Sound, Alaska, in April, July, and September 2006, and July 2007, to identify species assemblages and habitat use. At each location, fish were sampled with a 37-m long variable mesh beach seine in three nearshore habitats: bedrock outcrops, eelgrass meadows, and cobble beaches with kelp. A total of 49,060 fish representing 45 species were captured in 95 beach seine hauls. Catch-per-unit-effort did not differ by season but did differ by habitat type–CPUE was greater in eelgrass and kelp than in bedrock. Seasonal pulses in catch were evident for some species; pink salmon were captured only in spring and summer, Pacific herring only in summer and fall, and capelin only in fall. Species richness was greater in summer (34) than in spring (23) or fall (28), and greater in eelgrass (34) than in bedrock (22) or kelp (33). Species that were good discriminators among seasonal collections were pink salmon, saffron cod, crescent gunnel, and Pacific herring, whereas species that were good discriminators among habitat collections were crescent gunnel, tubesnout, bay pipefish, saffron cod, and Arctic shanny. Of the most abundant species captured, most were juveniles based on estimated size at maturity. The summer fish assemblage in western Prince William Sound has changed over the last 20 years, especially with the appearance in large numbers of saffron cod. Sites in this study can be monitored periodically to track future changes in fish assemblages and habitat that may result from local and regional human disturbance.

Alaska has about 55,000 km of shoreline and a wide diversity of near-shore habitats available to fish including eelgrass meadows, kelps, and exposed bedrock outcrops. These habitats are ecologically important for many fish species, providing shelter from predators and abundant food resources. Prince William Sound, a large embayment with numerous islands, provides extensive nearshore habitats that are protected from more exposed conditions on the outer coast. Although it is well established that over 100 fish species use the nearshore environment in Alaska, often in large numbers, what is unknown is their use of specific habitats and how that changes seasonally and with life stage.