Comparison of Diploid and Triploid Saugeye Recruitment, Growth, and Condition in Kansas Impoundments

• Published in: North American journal of fisheries management 2018-04, Vol.38 (2), p.446-453
• Main Authors: Koch, Jeff, Steffen, Chris, Goeckler, Jason, Marteney, Ron, Jagels, Josh, Brown, Bonnie
• Format: Article
• Language: English
• ISSN: 0275-5947; 1548-8675
• DOI: 10.1002/nafm.10044

Saugeyes (Walleye Sander vitreus × Sauger S. canadensis) are stocked by natural resource agencies to provide angling opportunities and biological control of abundant small‐bodied fishes. Concern has been raised regarding the stocking of fertile diploid saugeyes in Kansas waters due to potential genetic introgression into wild parental stocks and unintended natural reproduction in ecologically sensitive systems. As such, triploid saugeyes have been stocked in Kansas since 2006 but with minimal evaluation. We compared relative recruitment, growth, and condition of diploid and triploid saugeyes after stocking equal numbers of 3–6‐d‐old diploid and triploid saugeye fry in four Kansas reservoirs for 3 years. Saugeyes were sampled from study reservoirs annually (2014–2016) with autumn night electrofishing, and flow cytometry was used to determine the ploidy of sampled fish. Throughout the study, diploid fish composed approximately 80% of sampled saugeyes. Age‐0 year‐classes consisted of 67–100% diploid fish, depending on the study reservoir and sampling year. As saugeyes reached ages 1 and 2, similar patterns in relative recruitment were indicated, with diploids outnumbering triploids by approximately four times. At individual study impoundments, diploid saugeyes composed 75–87% of fish from all study year‐classes. Mean length of diploid saugeyes was generally greater than that of triploids at age 0, whereas mean lengths at ages 1 and 2 were similar for the two groups. Our results indicate that diploid saugeye fry represent a more efficient stocking option than triploid fry and that managers should carefully balance consideration of the relative recruitment of diploid and triploid saugeyes with potential genetic integration between Sander spp. when conducting supplemental stockings.