Sexual Practices of Healthy Lake Trout Uncovered
Ann Arbor, Mich. — Great Lakes lake trout populations were decimated in the 1950s and 1960s through the combined effects of sea lamprey and overfishing. After four decades of stocking to restore self-sustaining populations, significant lake-wide natural reproduction remains limited to Lake Superior. Much of the available evidence suggests the first year is the critical period for lake trout survival.
John Fitzsimons, a fisheries scientist with the Department of Fisheries and Oceans in Burlington, Ontario and his research team compared the reproductive strategies of lake trout in Keuka Lake, New York with those of Great Lakes stocks to try to understand what factors may continue to impede lake trout recovery.
"With the loss of native stocks that appeared to have a much wider reproductive repertoire than that now used by hatchery lake trout," Fitzsimons explains, "we lost the ability to assess the importance of different reproductive strategies, strategies that may be critically important in avoiding the effects of a number of mortality factors including wave turbulence and egg and fry predators."
By studying the reproductive strategies of successful populations in smaller inland lakes like Keuka Lake, which is one of New York's Finger Lakes, scientists can better understand what is necessary to aid restoration in the Great Lakes.
"The Finger Lakes, while smaller than the Great Lakes, suffer from many of the same stresses," Fitsimons says, "but because of their smaller size they are more amenable to the type of detailed observations necessary to evaluate reproductive strategies."
Fitzsimons and the Environment Canada dive team at the Canada Centre for Inland Waters used a combination of observation by remotely operated vehicle and egg nets to uncover the reproductive behaviour of Keuka Lake lake trout. Their studies revealed that lake trout in Keuka Lake spawn in 20-25 metres of water, much deeper than the 2-10 metres observed for stocked lake trout in most of the Great Lakes. Spawning occurred in December and was among the latest reported for the species, and some one to two months later than in the Great Lakes.
Although eggs were deposited over thin layers of shale, which provided an easily accessible meal for hungry yellow perch, the perch quickly became satiated and appeared to keep other egg predators like sculpins away. The surviving eggs settled into spaces among the shale where sculpins were less able to find and eat them, allowing a larger number of eggs to successfully incubate over winter.
Original Publication Information
Results of this study "Deepwater spawning by lake trout (Salvelinus namaycush) in Keuka Lake, New York" are reported by John Fitzsimons, Georgina Fodor, Bill Williston, Henk Don, Bruce Gray, Mike Benner, Todd Breedon, and Dave Gilroy in the latest issue (Volume 31, No. 1, pp. 1-10) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2005.
Contacts
For more information about the study, contact John D. Fitzsimons, Department of Fisheries and Oceans, Canada Centre for Inland Waters, Burlington, Ontario L7R 4A6; fitzsimonsj@dfo-mpo.gc.ca; (905) 336-4865.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; marlene.evans@ec.gc.ca; (306) 975-5310.
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.
