Using Genetic Markers as Individual Tags: a Case Study of a Mark–Recapture Estimate of Adult Muskellunge Population Size

Tag retention, tag reporting rate, misreading of tags, and other issues are common concerns with traditional tagging methods when marking fish for various stock assessments. These concerns have prompted the development and evaluation of alternative marking techniques by fisheries scientists. Wildlife scientists have overcome these obstacles by using genetic samples in lieu of tagging when studying rare, elusive, and capture-sensitive species. Recent technological advances facilitate similar alternatives for fisheries stock assessment. Muskellunge Esox masquinongy populations exist at low density and are difficult to sample; the Muskellunge is therefore an appropriate species to use in assessing this tool. We used microsatellite DNA analysis of samples from two connected lakes in north-central Minnesota to estimate adult population size using mark–recapture techniques. In total, 178 unique fish were identified during a trap-net marking period; 59 individuals were identified within an electrofishing resampling period, and 28 of those were recaptures, recognized by their matching genotypes. Based on these data, we obtained a population estimate of 369 adults (95% confidence interval = 269–470). The results of this study demonstrate the utility of genetic markers in place of traditional tagging methods for fish.