Variation in Reproductive Investment among Ohio Reservoir Largemouth Bass Populations

Abstract

Reproductive investment, expressed in terms of fecundity and egg quality produced by individual female fish, varies among populations for many species, reflecting plasticity in life history strategies related to intraspecific density dependence or environmental variability. Fisheries scientists and managers have long sought to understand differences in Largemouth Bass Micropterus salmoides population dynamics, yet basic life history traits, such as variation in reproductive investment, remain largely unknown. We determined the fecundity–weight and ovary energy density–weight relationships (where fecundity indexes egg quantity and ovary energy density indexes egg quality) for Largemouth Bass populations from 19 Ohio reservoirs and examined factors that were correlated with population‐specific differences. We found that both relationships varied among reservoir populations, with some interannual variation in reservoirs sampled in multiple years. We then related fecundity and ovary energy density to (1) population characteristics, including population density (as indexed by standard shoreline boat electrofishing CPUE, fish/h) and growth (as indexed by the growth coefficient k from the von Bertalanffy growth function); and (2) reservoir characteristics, including reservoir size (as surface area) and productivity (as Secchi transparency depth). We found that populations with greater fecundity also exhibited greater ovary energy density, indicating that the quantity and quality of reproductive output were greater in some populations than in others. Populations with high reproductive investment were associated with low Largemouth Bass density, fast growth, large reservoir size, and high productivity (i.e., low Secchi transparency). The among‐population variation in reproductive investment provides evidence of density‐dependent control of fecundity and egg quality.

Regional differences in energy allocation of black sea bass (Centropristis striata) along the U.S. Northeast Shelf (36°N to 42°N) and throughout the spawning season

“…Energy allocation can also be affected by overwintering preparation, where individuals at higher latitudes with pulsed environmental productivity rapidly acquire energy reserves, whereas fish at lower latitudes with constant productivity accumulate them more gradually (Schultz & Conover, 1997). Density dependence across a range can also influence energy allocation where fish in densely populated habitats exhibit lower reproductive investment and slower growth (Pritt et al ., 2020). Investigating how energy allocation differs across the wide distribution of certain fish species can provide insight into potential differences in reproductive output and recruitment success throughout a distribution.…”

“…Moreover, NS C. striata biomass has been increasing in the northern regions leading to higher population density in the MA region. Density dependence is known to affect growth and fecundity for a number of fish including the round goby (Neogobius melanostomus;Gutowsky & Fox, 2012;Houston et al, 2014), largemouth bass (Micropterus salmoides;Pritt et al, 2020), and European anchovy (Engraulis encrasicolus;Basilone et al, 2020). High population density in the MA region could therefore negatively affect energy allocation and reproductive output.…”