Evaluation of Scale Shape for the Identification of Walleye Stocks from Western Lake Erie

Abstract

Abstract We used the method of Jarvis et al. to characterize scale shapes of five stocks of walleye Stizostedion vitreum vitreum from western Lake Erie, to assess the effects of age, sex, and year of collection on scale shape, and to determine the level of accuracy for assignment of test individuals to their respective stocks based upon their scale shape. Neither sex, age, nor year of collection had significant effects on scale shape of walleyes from the Maumee River, Ohio. Using discriminant analysis we found some differences among scale shape from the five western Lake Erie stocks. The three Ohio stocks (Maumee and Sandusky rivers and Toussaint reef) were more similar in scale shape to each other than to the Lake St. Clair stocks (Clinton and Thames rivers), but classification rates of test individuals to their respective stocks were low. Differences in scale shape were more apparent when we compared an eastern-basin stock (Presque Isle, Pennsylvania) with western-basin groups, yet rates of successful c...