Recruitment of Young-of-Year Largemouth Bass in Relation to Size Structure of Parental Stock

The proportion of body weight contributed by the ovaries - the maturity index - was used to examine the relation between time of spawning and size of the parents for largemouth bass (Micropterus salmoides) in two Mississippi reservoirs. The maturity index increased before the fish spawned, reached a maximum, and then decreased as eggs were released. The maximum was interpreted as occurring at the onset of spawning. A plot of maturity index against time, according to size group, indicated that the larger fish attained a higher index and spawned first. This relationship was formulated with a multiple-regression model. The model, complemented with estimates of stock fecundity, larval growth, and mortality, was applied to populations exemplifying either few or numerous large brood fish to simulate the size distribution of young-of-year largemouth bass by late spring. These simulations indicated that populations with larger brood fish would produce bigger young-of-year largemouth bass by late spring as a consequence of earlier spawning. We postulate that largemouth bass populations with large adults can start spawning earlier and produce larger fingerlings that are better prepared to become piscivorous when prey fish begin to hatch. This could translate into faster first-year growth and the eventual recruitment of a larger portion of the year class into the fishery.