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Competition, Habitat Selection, and the Bathymetric Segregation of Two Rockfish (Sebastes) Species
Author(s) -
Larson Ralph J.
Publication year - 1980
Publication title -
ecological monographs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.254
H-Index - 156
eISSN - 1557-7015
pISSN - 0012-9615
DOI - 10.2307/1942480
Subject(s) - interspecific competition , ecology , waves and shallow water , habitat , dominance (genetics) , sebastes , biology , competition (biology) , reef , fishery , foraging , geography , fish <actinopterygii> , oceanography , geology , biochemistry , gene
Sebastes carnatus and Sebastes chrysomelas are morphologically and ecologically similar residents of rocky reefs off the coast of California. They segregate bathymetrically, with S. chrysomelas occurring shallower than S. carnatus. Each species extended its depth distribution where its congener was removed, and no distributional changes occurred in a control area. Thus both species tolerated conditions beyond their normal depth ranges, and were limited in part of their normal depth ranges by interspecific competition. Their segregation was apparently initiated by the preferential settlement of young fish from the plankton, S. chrysomelas in shallow water and S. carnatus deeper. Their segregation was maintained by interspecific territoriality. The distribution of S. chrysomelas, the socially dominant species, may also have been affected by a strong preference for food—rich areas that occurred mainly in shallow water. I postulate that such a preference would be due to the advantage of smaller home ranges in shallow water, where strong wave surge makes the shelter hole a more important part of a fish's territory. This postulated preference, along with aggression from S. carnatus, limited S. chrysomelas to shallow water. Because of its social dominance, S. chrysomelas aggressively excluded S. carnatus from preferred areas in shallow water.