Michigan Department of Natural Resource
Institute for Fisheries Research Report No.1771, 1970
Fecundity of Coho Salmon from Lake Michigan
Thomas M. Stauffer
Abstract.-Eggs from 17 mature coho salmon (Oncorhynchus kisutch) that were taken in October 1969 from the Platte River, a Lake Michigan tributary, were counted and their diameter measured. The presumed origin of these salmon was a plant of yearling coho in the Platte River in the spring of 1968. The yearlings had been obtained as eyed eggs from the Columbia River. Number and average diameter of eggs in Platte River salmon ranged from 2,229 and 0.27 inch in a 21.6-inch salmon to 3,812 and 0.31 inch in a 30.8-inch salmon. Egg number was positively correlated with salmon length (r = 0.80) and weight (r= 0.80). The regressions were: egg number = 172 total length (inches) - 1, 486, and egg number = 195 weight (pounds) + 1,594. Egg diameter was positively correlated (r = 0.91) with fish length. The regression was: egg diameter = .00542 fish length (inches) + 0.146 Lake Michigan coho salmon produced more eggs than West Coast coho salmon of comparable lengths. Thirty-three dead coho salmon from the Platte River were examined for egg retention; 27% retained 80% or more of their eggs. This was considerably greater than that recorded for West Coast coho salmon.