Hybrid Splake found on Lake Trout spawning reefs and in Brook Trout streams

Ann Arbor, Mich. —Management of Michigan’s fisheries focuses on healthy populations of self-sustaining fish and where these are not found, relies on hatchery fish for rehabilitating depressed fish populations and providing new fishing opportunities. In some circumstances the stocking of hatchery fish may conflict with management of wild populations.

Michigan’s state hatcheries rear splake, a fertile hybrid produced artificially by crossing female Lake Trout (Salvelinus namaycush) and male Brook Trout (Salvelinus fontinalis) that are stocked in near-shore waters of the Great Lakes and in selected inland lakes. This hybrid grows quickly and provides localized fisheries that are in high demand by anglers. Since approximately 56% of Splake are fertile, concerns have been raised over Splake stocking practices in Lake Superior especially near Brook Trout and Lake Trout spawning areas.

Fifteen Splake were collected from the Salmon Trout and Pilgrim rivers, and examined using DNA laboratory techniques to determine whether these fish showed signs of being hybrids. Four hybrids were identified among the 15 Splake from the two streams with self-sustaining Brook Trout populations. Fish were also collected at several Lake Trout spawning reefs near Copper Harbor and revealed that sexually mature Splake were present and spawning alongside and likely with Lake Trout.

Results from this study confirmed that stocked Splake were present and may pose a threat to the genetic integrity of spawning Brook and Lake Trout populations where they co-occur. These results suggest Splake stocking in Great Lakes waters where wild Brook Trout and Lake Trout are present should be reevaluated in consideration of management goals promoting wild self-sustaining populations of both species.

Original Publication Information

Results of this study, "Genetic and phenotypic evidence for splake presence in brook trout and lake trout spawning habitats," are reported by Mackenzie Fering, Casey Huckins, William Mattes, Edward Baker, Troy Zorn, John Littlefield, and Kim Scribner in Volume 42, Issue 3 of the Journal of Great Lakes Research, published by Elsevier, 2016.

Contacts

For more information about the study, contact Kim Scribner, Department of Fisheries and Wildlife, East Lansing, MI 48824; [email protected].

For information about the Journal of Great Lakes Research, contact Stephanie Guildford, Scientific Co-Editor, Large Lakes Observatory, University Minnesota Duluth, 2205 East Fifth Street, Duluth, Minnesota, 55812-2401; [email protected]; (218) 726-8064.