Pollock Conservation Cooperative Research Center
2005 Awarded Research Projects
Essential larval and juvenile fish habitat in nearshore waters of Kachemak Bay, Alaska
ABSTRACT
In temperate regions kelp can dominate hard-bottom nearshore communities, providing structure at the substrate and throughout the water column, which can be used by many invertebrates and fishes. Increasingly complex habitats can be beneficial to fish, however fish use of these complex habitats is poorly understood in northern latitudes, particularly for juvenile fish. The potential effects of macroalgal density and substrate complexity on nearshore fish communities were examined in Kachemak Bay, Alaska. Fish were collected from multiple sand, understory, and understory and canopy sites, along with substrate and algal complexity measurements. SMURFs, light traps, shrimp pots, and SCUBA visual surveys were all employed in these collections. Fish abundance and composition varied temporally across habitats. Adult fish communities were comparable among similar habitats, with younger fish assemblages being similar across macroalgal sites but distinctly separate from sandy sites. The dominant fish included gadids, pleuronectids, hexagrammids, and sebastids. Larger gadids were captured in all three habitats, while smaller individuals were primarily encountered in macroalgal habitats. Pleuronectids were only captured in sandy sites. Adult hexagrammids were captured in macroalgal habitats; however, juveniles were not encountered. Adult sebastids were only encountered in understory sites, while smaller sebastids were captured in all three habitats. All dominant fish families were significantly different in habitat use both temporally and ontogenetically, but these differences were family specific with different families utilizing different habitats. Community analysis showed that different habitat complexities supported distinctly different fish assemblages and that these assemblages were predictable based on substrate composition and the presence or absence of kelp. This study indicates that different groups of fish may have different habitat preferences in Alaska's nearshore waters requiring different management strategies.
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