Fluctuations in the Success of Year-Classes of Whitefish Populations with Special Reference to Lake Erie

• Published in: Journal of the Fisheries Research Board of Canada
• Main Author: Lawler, G. H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1965
• Subjects: Great Slave Lake; Lesser Slave lake
• Online Access: http://dx.doi.org/10.1139/f65-106; http://www.nrcresearchpress.com/doi/pdf/10.1139/f65-106

Year-class strength varied markedly in whitefish (Coregonus clupeaformis Mitchill) populations, and the presence of unusually strong year-classes was evident in the commercial catch. Fluctuations in the catch characterized the Lake Erie fishery and the unusually high production in some years was attributed to the occurrence of strong year-classes in the fishery. The most outstanding year-class in Lake Erie originated in the spring of 1944 and resulted in the highest catches ever recorded in the year 1948 and 1949. The next strongest year-class occurred in 1936 and resulted in high production in 1940 and 1941. The 1926 year-class was relatively strong and was responsible for subsequent high production. Other peaks in production could not be attributed to the presence of strong year-classes, as no age composition data were available, but it was inferred that strong year-classes were responsible. The 1943 year-class was unusually successful in Lake Huron, Green Bay (Michigan), and the upper portion of Lake Michigan. There is some evidence that year-classes of above average strength may have occurred in Lake Huron in the past, but were not as prevalent or as striking as those that occurred in Lake Erie. The 1944 year-class was dominant in the Lesser Slave Lake whitefish catch. There is no evidence that unusually successful year-classes have ever appeared in Lake Ontario, Lake Winnipeg, Great Slave Lake, or Heming Lake.The whitefish is at the southernmost limit of its distribution in Lake Erie and here environmental conditions, especially temperature, have become progressively unfavorable. The increase in the abundance of species accustomed to more southern warmer conditions was further evidence that the lake itself is becoming warmer at a rather rapid rate.In Lake Erie the above average strength of the 1926, 1936, 1944, and other year-classes which were considered strong cannot be explained on the basis of the size of spawning population, the number of hatchery-raised fry planted, nor on the effect of such ...