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Ontogenetic Habitat Shifts of Juvenile Bear Lake Sculpin
Author(s) -
Ruzycki James R.,
Wurtsbaugh Wayne A.
Publication year - 1999
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1999)128<1201:ohsojb>2.0.co;2
Subject(s) - profundal zone , littoral zone , sculpin , habitat , juvenile , ecology , predation , diel vertical migration , range (aeronautics) , pelagic zone , juvenile fish , biology , cottus , fishery , fish <actinopterygii> , materials science , composite material
Bear lake sculpin Cottus extensus exhibit ontogenetic habitat shifts during their initial year of life. Distribution and habitat switching was measured with bimonthly bottom‐trawl surveys repeated throughout the summer. Patterns of daily growth increments on otoliths were used to measure the history of habitat residence, individual size at the time of the habitat switch, and habitat‐specific growth rates. Laboratory experiments and known‐age fish confirmed daily increment formation of otoliths. After dispersing during an initial pelagic larval stage, postlarval juveniles settled in both the warm, food‐rich littoral zone and the cold, unproductive profundal zone. During summer, initial profundal‐zone inhabitants underwent a unidirectional habitat shift to the more productive littoral zone. Fish that moved to the littoral zone grew twice as fast as those in the profundal zone and encountered little apparent predation mortality risk there. Habitat shifts were therefore consistent with both growth optimization and predatory avoidance. However, shifts occurred at a wide range of body sizes throughout the summer. The large spatial scale of the lake, limited swimming ability of juvenile fish, diel migratory behavior, and lack of complex habitat structure may preclude shifts at discrete body sizes for this species.