Fisheries Behavioral Ecology - Abstracts
Stoner, A.W. and R.H. Titgen. 2003. Biological structures and bottom type influence habitat choices made by Alaska flatfishes. Journal of Experimental Marine Biology and Ecology 292:43-59.
Abstract
Habitats of flatfishes are ordinarily characterized on the basis of depth, sediment type, and
temperature. However, features of the benthic environment such as structures created by sessile
organisms and different bedforms may also influence habitat suitability. In this investigation, we
tested the hypothesis that habitat choices made by juveniles of two economically important flatfishes,
Pacific halibut (Hippoglossus stenolepis Schmidt) and northern rock sole (Lepidopsetta polyxystra Orr and Matarese), are influenced by structures on the sea floor. In the laboratory, age-0 individuals
of both species demonstrated high positive selectivity for habitats with structure (natural sponges,
bryozoan mimics, bivalve shells, and sand waves) over smooth sand substratum. The degree of
choice was influenced significantly by density of structures, particularly sponges. Small halibut (48–77 and 90–144 mm) were more selective than larger juveniles (270–337 mm), and in sponge habitat
juvenile halibut were more selective than comparably sized rock sole. Preference for habitat with
structure increased significantly with increasing light level, suggesting that choices were made
partially on the basis of visual cues or as related to perceived threat. However, the preference for
structured habitat was maintained in darkness. Beam trawl collections made in a flatfish nursery
ground near Kodiak, Alaska, revealed that the abundances of age-0 Pacific halibut and rock sole
were closely correlated with amounts of shell and echinoderm bycatch in the tows, corroborating the laboratory observations of affinity for habitat structure. Strong preferences for structured habitat in
young halibut and rock sole indicate the importance of benthic structures that are frequently removed
by fishing gear.
Last updated
27 April, 2007
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