Localized Spatial and Temporal Variation in Reproductive Effort of Florida Bass

Abstract

Few studies have explored annual reproductive effort of fish populations, yet factors such as skipped spawning could influence recruitment processes. We estimated the number of broods produced annually as an index of reproductive effort for Florida Bass Micropterus floridanus across four lakes in north-central Florida. Snorkel surveys were used to estimate reproductive effort in the lakes from 2010 to 2012. Mark–recapture methods were used to estimate the abundance of Florida Bass in each lake during each year. All four lakes contained high-density Florida Bass populations that showed evidence of relatively slow growth. Average relative weight in all populations was low, ranging from 65.4 to 68.8 for adults (≥25.0 cm TL). Annual reproductive effort (estimated number of broods) varied among lakes and across years. We found evidence for multiple spawning events per adult and for skipped spawning. Devils Hole Lake produced the highest number of broods in all 3 years, ranging from 1.62 broods/spawner in 2012 to 3.72 broods/spawner in 2011 (median = 3.24 broods/spawner in 2010). All other populations exhibited skipped spawning, with the proportion of nonreproductive adults varying across years. Picnic Lake fish had the lowest number of broods overall (only 0.02 broods/spawner in 2011 and 0.01 broods/spawner in 2012). The other two lakes showed variable levels of spawning effort. Spawner abundance in these populations was not related to the estimated annual number of broods, contrary to the general assumption made for many population models. Variability in annual reproductive effort may be more common than anticipated, potentially clouding the relationship between spawner abundance and recruitment. Estimation of annual reproductive effort may provide insight into density-dependent population regulation and recruitment processes.

Received February 14, 2013; accepted July 22, 2013

ACKNOWLEDGMENTS

This study was funded by the Sport Fish Restoration Program through the Florida Fish and Wildlife Conservation Commission. We thank W. Porak, C. Suski, D. Philipp, and J. Dotson for input on study design and approach.