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Crappie Hybridization in Southern Minnesota Lakes and Its Effects on Growth Estimates
Author(s) -
Miller Loren M.,
McInerny Michael C.,
Roloff Jason
Publication year - 2008
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/m07-070.1
Subject(s) - hybrid , biology , microsatellite , genetics , botany , allele , gene
Species‐specific microsatellite DNA markers were used to identify hybrids of black crappies Pomoxis nigromaculatus and white crappies P. annularis and to determine the effect of hybridization on crappie growth. Specifically, we determined the contribution of hybrids to the skew in length frequency distributions that is frequently observed within year‐classes of sympatric crappie populations and the resulting upward bias on growth estimates for the two species. Hybridization was found throughout most southern Minnesota lakes that contained both species, but the frequency of hybrids was low in our length‐stratified subsamples (mean frequency of first‐generation (F 1 ) hybrids among all lakes and year‐classes = 3.2%; mean frequency of advanced‐generation (F x ) hybrids = 1.4%). Among the 22 study lakes, only 2 contained no hybrids (based on polymerase chain reaction amplification of microsatellite loci). The F 1 hybrids were disproportionately classified as black crappies under a Minnesota Department of Natural Resources (MNDNR) classification system that only allowed assignment of crappies to the two parental species. In one lake sampled over multiple years, we found F 1 hybrids in only 5 of 14 year‐classes of MNDNR‐classified black crappies and in 4 of 11 year‐classes of MNDNR‐classified white crappies, indicating annual variation in the prevalence of hybridization. Consistent with their faster growth and tendency to be classified as black crappies, F 1 hybrids accounted for 82% of all statistical outliers in length distributions of MNDNR‐classified black crappie age‐classes and 33% of the infrequent outliers in MNDNR‐classified white crappie age‐classes. The presence of F 1 hybrids in our subsamples produced an upward bias in back‐calculated length estimates for black crappies but had nonsignificant effects on white crappie length estimates. The effects of hybridization should be taken into account when estimating growth in crappie species from sympatric populations.