Reactions of Juvenile Pacific Salmon to Light

• Published in: Journal of the Fisheries Research Board of Canada
• Main Authors: Hoar, W. S., Keenleyside, M. H. A., Goodall, R. G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1957
• Subjects: Pink salmon
• Online Access: http://dx.doi.org/10.1139/f57-036; http://www.nrcresearchpress.com/doi/pdf/10.1139/f57-036

When given a choice between light and dark areas, schools of chum or pink salmon fry remain in the light, sockeye fry prefer the dark and coho fry show no marked preference for either. Newly emerged sockeye fry are the most strongly photonegative, remaining mostly under stones. Older sockeye fry move more into the light. Sockeye and coho smolts stay in the dark more than sockeye and coho underyearlings. Territorial and "escape" behaviour by fish in the experimental apparatus may obscure these reactions to light. Soon after emerging from the gravel, pink fry swim near the surface under low light intensity and retreat to deeper water in brighter light. Older pink fry seem indifferent to changing light. Recently emerged chum salmon fry do not respond in this way to changing illumination, although older fry tend to swim closer to the surface. This difference between pink and chum salmon fry may be related to differences in schooling behaviour and alarm responses of the two species.