Growth, Natural Mortality, and Predicted Response to Fishing for Largemouth Bass and Smallmouth Bass Populations in North America

Abstract Growth, natural mortality, latitude, elevation, average air temperature, and degreedays exceeding 10°C were summarized for 698 populations of largemouth bass Micropterus salmoides and 409 populations of smallmouth bass M. dolomieu in North America and used in simulations to determine the effects of fishing on populations of varying productivity. Length at age and von Bertalanffy growth equation parameters varied greatly among populations and resulted in ages at quality length (300 mm for largemouth bass and 280 mm for smallmouth bass) ranging from 1 to 10 years for largemouth bass and from 2 to 9 years for smallmouth bass. Natural mortality also varied widely, but the conditional annual rate averaged 35% for both species. Age at quality length was used as an index of growth rate and was positively correlated (P < 0.05) with latitude and elevation for largemouth bass and with latitude for smallmouth bass. Age at quality length was negatively correlated (P < 0.05) with mean air temperature and degr...