Effects of salinity and temperature acting in concert on sustained swimming speed of juvenile Coho salmon (Oncorhynchus kisutch)
Date
1972
Authors
Glova, G. J. (Gordon John)
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Abstract
The effects of salinity (freshwater - 20 %) and temperature (3- 23C) acting in concert on sustained swimming speed of juvenile coho salmon (4.9-11.4 cm) acclimated to test conditions were examined in a stamina tunnel. Relations between swimming performance and test parameters were examined by response surface analysis, employing a second order polynomial as a model.
Sustained swimming speed of coho fry - presmolt developmental stages declined with decreasing temperatures from about 20 C, but were little affected by salinities ranging from freshwater to 20 %S. In the smolt stage, temperature effects were similar but salinity effects more pronounced, with maximum levels of performance attained at near isotonic salinities. Optimum locomotor capacity occurred at about 20C in all developmental stages tested, ranging from 7.2 Lengths/second (L/sec) in fry to 5.5 L/sec in smolts. Relative swimming capacity was size dependent, and the extent of this dependence was related to temperature. With decreasing temperatures, smaller fish showed a greater decrease in relative swimming capacity. At 3C, size effects on relative capacity were virtually nonexistent and all test stages attained a performance of about 3.5 L/sec.
The results suggest that underyearling coho have the capacity to perform locomotor-dependent behaviours in brackish waters, up to a salinity of at least 20 %, with an efficiency equivalent to that in freshwater.