**The title, authors, and abstract for this completion report are provided below.  For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**

Natural Lake Trout Strain Identification in Lake Huron

Wendylee Stott^{2, 5},  David Reid³, James Johnson⁴

² Great Lakes Science Center-USGS

Ann Arbor, MI

 

³ Ontario Ministry of Natural Resources

Upper Great Lakes Management Unit

Owen Sound, ON

 

⁴ Michigan Department of Natural Resources

Alpena Great Lakes Fisheries Station

Alpena, MI

 

⁵ Corresponding author

email: wstott@usgs.gov

tel:  734-214-7242

Abstract

Considerable financial commitments have been made to restore lake trout to the Great Lakes and lake trout rehabilitation remains one of the primary goals of restoration and management programs.  Although successful natural reproduction of lake trout in the Great Lakes outside of Lake Superior has been limited, reproduction has occurred in Lake Huron.  Procedures for genetic stock identification were applied to lake trout samples from Lake Huron to assess the contribution of different lake trout strains to successful natural reproduction.  Samples of naturally produced lake trout and recaptured hatchery lake trout were analyzed to determine which hatchery stocks produced them using individual assignment tests.  Samples were obtained at five collection sites.  Three of the sites are in Georgian Bay (Owen Sound, Parry Sound, and Iroquois Bay), South Bay Mouth is on the southern shore of Manitoulin Island, and the fifth site is in the main basin of Lake Huron (Parking Lot Reef).  The results of the assignment tests were compared to stocking rates to determine if stocks survive and contribute to natural reproduction at the same rate as they were stocked.  Assignment accuracy was low overall (55%), primarily due to the large number of baseline samples used in each comparison, but also because some of the hatchery strains are similar genetically (Lake Manitou and splake backcross and Michipicoten Island and Slate Island).  Overall, hatchery strains developed from lake trout from Georgian Bay contributed more than those developed from lake trout from Lake Superior.  Over 70% of the unclipped lake trout were classified as inter-strain hybrids, many of them between strains with dissimilar origins.  Coefficients of relatedness were low overall indicating that spawners are not closely related and/or the size of the spawning stock is relatively large.  Further monitoring of natural reproduction in Lake Huron will help determine if trends observed to date continue and also will help to understand possible effects of effective population size and outbreeding depression on the overall fitness of rehabilitated stocks of lake trout in Lake Huron.