Genetic Pedigree Reconstruction Detects Bias in Largemouth Bass Nest Sampling Procedures

Abstract

Fish recruitment can be influenced by the direct effects of and interactions among biological, environmental, and anthropogenic factors. However, interpretation of data that quantify associations between recruitment during early ontogenetic stages and potential underlying causal factors at whole-population scales can be confounded by the uncertainties associated with data collection. For nest-building species, biases may result from observational methods used to locate nests and determine nest-specific offspring survival. Such biases may hinder efforts to associate estimates of individual reproductive success or failure with recruitment variation at the population level. During spring 2010, Largemouth Bass Micropterus salmoides nests in a 24-ha Michigan lake were surveyed using established observational methods, and genetic data and pedigree reconstruction were used to assess the reliability of those methods. We georeferenced observed nests, visually assessed whether eggs from nests survived to the swim-up fry stage, and collected offspring from each observed nest for multilocus genotyping to characterize nest-specific pedigrees. In late summer, we captured age-0 Largemouth Bass for genotyping and used pedigree reconstruction to determine their nests of origin. Comparisons of genetic pedigree and observational data revealed that genetic methods offered a novel, powerful way of evaluating nest observation procedures. We estimated that 50% of the nests that contributed age-0 recruits were not observed by field crews; 40% of observed nests that produced late-summer age-0 Largemouth Bass (as determined based on genetic data) were not observed to produce swim-up fry during the nesting period (i.e., were misclassified as having failed). Our analyses suggest that nesting observations underestimate nest abundance and incorrectly classify some nests as having failed to produce swim-up fry, thus potentially creating a biased representation of nest-specific contributions to recruitment.

Received March 26, 2013; accepted October 17, 2013

Published online February 10, 2014

ACKNOWLEDGMENTS

This work was funded by the Fisheries Division of the Michigan Department of Natural Resources. Additionally, funding was provided by the Center for Water Science at Michigan State University and by the Ball Fellowship from the Department of Fisheries and Wildlife, Michigan State University. We thank K. Farrel, J. Freed, J. Homola, M. Horsely, J. Kanefsky, A. Kilbourn, C. Koleski, B. Riser, J. Smith, K. Smith, P. Thompson, A. VanSickle, R. Zimmerman, and H. Ziegenmeyer for assistance in the field and laboratory. Finally, we thank the editorial staff and two anonymous reviewers for comments on earlier versions of this manuscript that greatly improved the presentation.