Michigan Department of Natural Resources
Fisheries Research Report No.1806, 1973

Fecundity of Coho Salmon From Lakes Michigan and Superior


Thomas M. Stauffer


       Abstract.-Coho salmon in five spawning runs were examined for egg number, egg size, ovary weight, nonviable eggs and eggs retained. One spawning run in a Lake Michigan tributary (Platte River) in 1969 originated from West Coast eggs while two spawning runs there in 1970 and 1972, and runs in two Lake Superior tributaries (Anna and Huron rivers) in 1970, originated from salmon that had spent their entire life in fresh water. Numbers and sizes of eggs were significantly correlated with salmon length and weight in all spawning runs except in the Anna River, where egg size and salmon length were not correlated. For salmon from the Platte River, eggs per female averaged 3, 096; average egg diameter was 7. 2 mm. Weight of ovary of these salmon was about one-fourth the total body weight. Nonviable eggs comprised less than 3% of the total egg number, and egg retention of salmon found dead was about one-third of the total egg complement. There was no important difference in any of the above parameters between salmon originating from West Coast eggs and eggs produced in fresh water. Number and size of eggs from salmon produced in the Great Lakes were similar to that found for West Coast coho salmon. For salmon in the two Lake Superior tributaries, number of eggs per female averaged 1, 973; average diameter was 5. 2 mm. Their ovary weight was only about one-eighth of the total body weight, the percentage of nonviable eggs was less than 1%, and one-eighth of the total egg complement was retained by salmon found dead. Platte River fish differed from Lake Superior fish in that they had both more eggs and larger eggs, a greater percentage of their weight was made up of ovarian tissue, and they appeared to have a higher rate of egg retention. Eggs of salmon in all five samples appeared normal in every respect, which suggests that coho salmon will become part of the indigenous fauna of the Great Lakes.