Fish use and size of eelgrass meadows in southeastern Alaska: A baseline for long-term assessment of biotic change

Johnson, SW Thedinga, JF

NORTHWEST SCIENCE 79:2-3 141-155

Eelgrass meadows at six sites in southeastern Alaska were sampled for fish assemblages and mapped to establish a baseline of information for long-term assessment of biotic change. All sites were sampled in spring 2001, 2002, and 2003: four of the sites were also sampled in winter 2003. A total of 44 seine hauls from all sampling periods yielded 58,902 fish comprising 45 species. Fish abundance in spring differed significantly among sites but not among years. The most abundant commercially important or forage fish species captured were chum salmon, Pacific herring. pink salmon, coho salmon, and Pacific sand lance: mean size of each of these species was <= 100 mm FL. For those sites sampled seasonally in 2003, fish were significantly more abundant in spring than in winter. At each site, three different species accounted for most (>= 69%) of the total catch. Size of eelgrass meadows varied annually; maximum percent change in area ranged from -13% to +27%. Eelgrass density ranged from 336 shoots/m(2) to 1,544 shoots/m(2), and dry biomass ranged from 36 g/m(2) to 71 g/m(2). Periodic re-sampling of the eelgrass sites established in this study will allow resource managers to track long-term and large-scale changes in fish communities and habitat that may result from shoreline development or global climate change.

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