| Approximately 880,000 triploid chinook salmon (Onchorynchus tshawytscha) were stocked into the Great Lakes from 1985 through 1990 in an attempt to produce a trophy salmon fishery. Triploidy was induced with a heat shock of 28.5 C. for 10 minutes at 10 minutes after fertilization. Female chinook salmon have not returned to the monitored release sites at Little Manistee River or Swan Creek. Six mature male triploids have returned to these sites. Triploid males were the same size and similar in appearance diploid fish, but no milt produced. GSI values of triploid males were significantly lower than that of diploids male chinook. Returns of triploid males was significantly lower than returns of diploid male chinook salmon from the same year class. A small population of triploid chinook salmon were held in a pond at the Wolf Lake Hatchery until maturity. Triploid female chinook were not significantly different in size, showed no secondary sexual characteristics, produced no mature oocytes and their GSI was significantly lower than diploid females. Unfortunately, no male triploid chinook remained in the population due to a hatchery stocking error. |
