Sperm Quality of Hatchery-Reared Lake Trout Throughout the Spawning Season

Abstract

The objective of this study was to investigate variation in sperm quality metrics (motility, velocity, linearity, longevity, and density) of hatchery-reared Lake Trout Salvelinus namaycush throughout the spawning season. Seasonal variation in sperm quality was investigated using both a regression and repeated-measures approach. Sperm was collected from the same 16 individuals over four sampling periods, separated by 3-week intervals. Regression analyses showed that 7–27% of the variation in sperm traits could be explained by seasonal variation, indicating that seasonality can have a significant impact on the quality of sperm. Significant positive linear relationships were found for percent motility and linearity at 5 s postactivation. Significant negative quadratic relationships were found for velocity at 5 s postactivation, longevity, and density, whereas a positive quadratic relationship was found for linearity at 10 s postactivation. Repeated measures ANOVAs showed a significant effect of season for percent motility and linearity at 5 and 10 s postactivation, velocity at 10 s postactivation, and longevity. Our findings are important for optimizing fertilization protocols for hatchery production and can also be used to understand reproductive biology and ecology of wild Lake Trout stocks.

Received March 15, 2012; accepted June 30, 2012

ACKNOWLEDGMENTS

This research was funded by the Natural Sciences and Engineering Research Council of Canada in the form of Discovery Grants and Research Tools and Instrumentation Grants, as well as grants awarded by the University of Windsor, to T.E.P. and a Ministry of Research and Innovation postdoctoral fellowship grant to I.A.E.B. Bill Sloan, Scott Ferguson, and Ben Lewis of the Ontario Ministry of Natural Resources (OMNR) provided invaluable assistance at the OMNR Codrington Fisheries Research Facility.