Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists
Paternity Analysis of Pooled-Milt Spawning Practices for a Muskellunge Broodstock
Loren M. Miller
Abstract.—Minnesota Department of Natural Resources biologists use milt from multiple Muskellunge Esox masquinongy males to fertilize eggs of a single female. Protocols recommend multiple males to provide sufficient milt volume and increase genotypic diversity; pooling milt addresses concerns about infertile males and practicality in the lakeside setting where wild adults are spawned. To provide sufficient males, some may be held and reused or their milt may be preserved. Using microsatellite DNA loci, I assessed paternity of fry from 22 lots, each derived from 1 female and 2–6 males. Males had significantly different numbers of offspring in 17 of 22 lots (P < 0.05). Linear mixed models indicated that paternity success of reused males or held milt was only 44% that of new males when in competition, but males also had significantly different success in four of seven lots with all new or reused males. Because this was an assessment of current practices and not experimentally controlled, I could not determine what combination of unequal milt volume, unequal sperm count, and sperm competition accounted for the unequal offspring contributions. Regardless of the causes, changes in protocols could be considered to reduce disparities in offspring numbers among males and thus enhance the maintenance of genetic diversity in muskellunge broodstocks.