Fin Erosion in Intensively Cultured Walleyes and Hybrid Walleyes

Abstract Fin erosion was observed in two cohorts of walleyes Stizostedion vitreum and one cohort of half-sibling hybrid walleyes (walleye × sauger S. canadense) raised from hatch in fiberglass tanks. All size and relative fin length (fin length/standard length) differences between stocks within the same year were statistically significant. Morphometric measurements of the 1993 cohorts of walleyes and half-sibling hybrids were made in 1994 at 414 d posthatch (dph). Caudal fin erosion was more severe in walleyes than in hybrids, but hybrid walleyes had more severe pectoral and pelvic fin erosion. Also, compared with mean relative fin lengths from reference sources, pelvic fins of walleyes were about 45% of the reference values versus 28% for hybrids; relative pectoral fin length for walleyes was 78% but only 28% for hybrids; relative caudal fin length was 94.9% for walleyes and 130% for hybrids. In the 1995 cohorts, we compared measurements of 206-dph walleyes from Spirit Lake, Iowa (SLW), with 227-dph dome...