Behavioral Stock-Isolating Mechanisms in Great Lakes Fishes with Special Reference to Homing and Site Imprinting

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Author: Horrall, Ross M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1981
• Subjects: Pink salmon
• Online Access: http://dx.doi.org/10.1139/f81-201; http://www.nrcresearchpress.com/doi/pdf/10.1139/f81-201

A moderately high degree of reproductive isolation is necessary for the formation and maintenance of discrete stocks of fish. This reproductive isolation can be developed through spawning site imprinting and homing—behavioral mechanisms that are apparently very common in fish. During some part of their early life history, the fish become imprinted to, or conditioned to, environmental characteristics of the spawning site and/or to the pheromonal characteristics of their stock. At sexual maturity, they show an orientation-homing behavior back to the natal area where spawning then occurs reinitiating the cycle. Over time, stock-specific adaptations are made to the local environment which can involve changes in the morphological, physiological, or behavioral characteristics of the fish. Research on salmonids has provided the best evidence for site imprinting and natal homing in fish. Tagging and transplantation experiments with these species have been especially important sources of information. In coho salmon (Oncorhynchus kisutch), olfactory homing and olfactory site imprinting have been demonstrated by artificial imprinting techniques; it was found that the critical period for imprinting occurred during smoltification at an age of 15 or 16 mo. Most species do not undergo smolting, and imprinting occurs at a very early stage in the life history. It is hypothesized that the information which is imprinted about the natal site may be obtained from one or more of the following: odors in the water flowing over the site; odors originating from the site itself; and stock-specific pheromones emitted directly from the fish or from their waste products. Differences in characteristics of homing and imprinting in relation to the formation and maintenance of stocks are discussed for several Great Lake species including coho salmon, pink salmon (O. gorbuscha), lake trout (Salvelinus namaycush), white bass (Morone chrysops), and walleye (Stizostedion vitreum vitreum). Inferences are made about how these characteristics relate to ...