Length-at-age and Size-Selective Mortality of the Western Basin Lake Erie Walleye (Sander vitreus) Population, 2000-2008

摘要

Size-selective mortality is common in systems where selective harvesting targets a specific size- or age-class. In general, commercial and recreational fisheries selectively remove the largest and fastest growing individuals, which may have evolutionary consequences. My goals were to examine length-at-age patterns, age at first and full recruitment to the fishery, and to determine if size-selective mortality existed in a commercially and recreationally fished population of walleye in Lake Erie of the Laurentian Great Lakes between 2000 and 2008. Mean fork length-at-age was found to increase from west to east within Lake Erie for age 2 and 3 walleye. However, mean fork-length at age 1 was not statistically different among sampling areas. Walleye first recruited to the fishery at age 1 and were not fully recruited by age 3. Smaller (slower growing) individuals were found to disproportionately survive to older ages than faster-growing fish, indicating that size-selective mortality of larger (faster growing) fish occurred. Size-selective mortality will likely have a negative effect on morphological (i.e., body size) and life history traits.