An Atlas On The Distribution And Habitat Of Common Fish In Shallow Nearshore Waters Of Southeastern Alaska
October 17, 2005
Distribution and habitat use are presented on the 50 most abundant fish species captured in shallow nearshore waters (< 20 m offshore and < 5 m deep relative to mean lower low water (MLLW) of southeastern Alaska. Fish were captured with a beach seine at 41 locations from 1998 to 2004. At each location, habitats sampled included sand or gravel beaches with no attached vegetation, cobble beaches with understory kelps (e.g., Laminaria saccharina), soft bottom (sand, silt, or mud) beaches with eelgrass (Zostera marina), and steep bedrock outcrops. A total of 538 seine hauls yielded 448,166 fish. Based on total catch, the three most abundant species were walleye pollock (Theragra chalcogramma), Pacific sand lance (Ammodytes hexapterus), and Pacific herring (Clupea pallasii). Mean catch per seine haul was greatest in eelgrass for 30 of the 50 most abundant species. Juveniles dominated the catch of all species captured. For example, mean size of walleye pollock, Pacific sand lance, and Pacific herring was less than 100 mm fork length. Distribution patterns were evident for many fish species; some are widely distributed throughout southeastern Alaska (crescent gunnel, Pholis laeta), whereas others are confined to southern waters (kelp perch, Brachyistius frenatus) or more outside coastal waters (black rockfish, Sebastes melanops). Shallow nearshore waters support a diverse and abundant community of fish, many of commercial importance. Information on distribution and habitat of nearshore fish assemblages will help resource managers identify and protect coastal areas at risk to human disturbance.
The Magnuson-Stevens Fishery Conservation and Management Act of 1996 requires the identification of essential fish habitat (EFH) for species included in federal fishery management plans (FMPs) (Minello 1999). Identifying EFH requires basic information on fish distribution and habitat use. In southeastern Alaska, some information exists upon which to infer general distribution for species included in the Gulf of Alaska FMP (North Pacific Fishery Management Council 2002). For many FMP species in Alaska, however, such information is limited, especially for early life stages. In particular, resource managers need information on fish use of shallow nearshore (< 20 m offshore and < 5 m deep) habitats to protect areas critical to fisheries.
Southeastern Alaska has about 33,600 km of tidal shoreline (Department of Interior 1994) and a wide diversity of estuarine and marine habitats including fiords, bays, channels, and straits. Nearshore areas of intertidal and subtidal vegetation are considered habitat areas of particular concern because of their high value as fish habitat and vulnerability to human disturbance (North Pacific Fishery Management Council 2002). Two types of submerged vegetation, eelgrass (Zostera marina) and kelps (e.g., Laminaria saccharina) are widely distributed in lower intertidal and shallow subtidal areas along the coast of Alaska (McRoy 1968, Phillips and Watson 1984, O' Clair and Lindstrom 2000, Wyllie-Echeverria and Ackerman 2003). Other common habitat types in Alaska include non-vegetated substrates of sand or gravel and steep bedrock outcrops. Little information is available on fish use of these habitat types.