Intrapopulation Variation in the Breeding of Male Pink Salmon ( Oncorhynchus gorbuscha) from a Lake Superior Tributary

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Author: Noltie, Douglas B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1990
• Subjects: Oncorhynchus gorbuscha; Pink salmon
• Online Access: http://dx.doi.org/10.1139/f90-019; http://www.nrcresearchpress.com/doi/pdf/10.1139/f90-019

Studies of breeding pink salmon (Oncorhynchus gorbuscha) from the Carp River, eastern Lake Superior, indicate that males seek fertilizations using two behavioural tactics. In 1985, a large run resulted in high breeding ground densities. During this run, males that resembled females were seen seeking fertilizations by sneaking rather than by competing for proximity to females. Morphological studies in 1985 confirmed the presence of males resembling females, their secondary sexual characters (hump height) being relatively less developed than in typical males. Although in poorer condition, such female-like males were reproductively mature, had returned to spawn at ages typical for this population, and had committed biomass to gonad no differently than had typical males. Furthermore, their spawning performance did not differ from typical males, as assessed both by the amount of gonad they retained unspawned at death and by their spawning ground life expectancies. In contrast, males attempting to sneak fertilizations were not observed during the small 1984 run when densities were low and males were generally in better condition than in 1985. Together, these results indicate that male pink salmon exhibit alternative breeding tactics. However, the demonstration of these tactics appears linked more to proximate factors (density and condition) than to divergent life history strategies as in other salmonid species.