J. Great Lakes Res. 32:386–394 Internat. Assoc. Great Lakes Res., 2006 386 Relative Survival of Lake Trout Stocked at Different Sizes and Quality in Lake Michigan Charles R. Bronte 1,* , Patrick C. McKee 2 , Mark E. Holey 1 , Michael L. Toneys 2,† , and Paul E. Haver 3 1 U.S. Fish and Wildlife Service Green Bay Fishery Resources Office 2661 Scott Tower Drive New Franken, Wisconsin 54229 2 Wisconsin Department of Natural Resources 110 South Neenah Avenue Sturgeon Bay, Wisconsin 54235 3 U. S. Fish and Wildlife Service Jordan River National Fish Hatchery 6623 Turner Road Elmira, Michigan 49730 ABSTRACT. Beginning in 1995, the size of yearling lake trout (Salvelinus namaycush) stocked into the upper Great Lakes was increased based on the assumption that these fish would be healthier and survive better since natural mortality is thought to be inversely proportional to body size. We compared the post- release, relative survival of paired stockings of lake trout reared to 44 fish/kg (standard size) with larger fish reared to 22–26 fish/kg (enhanced size) in Lake Michigan. About 60,000 lake trout each of the stan- dard and enhanced sizes for the 1994–1997 year classes were released as yearlings in spring near Clay Banks Reef, Wisconsin, and identified with coded-wire tags and an adipose fin-clip. Recaptures were made from 1997 to 2003 in four gill net surveys conducted in spring and fall near the release location. Comparisons of catch-per-unit of effort corrected for numbers stocked generally indicated no significant differences in relative survival of standard and enhanced lake trout. An autopsy-based assessment of overall fish health and condition indicated few measures where significantly different between standard and enhanced lake trout prior to stocking. Size differences between standard and enhanced fish remained statistically significant at all observed ages at recapture; however growth rates were the same for the two groups. Stocking numbers at certain sites on Lake Michigan were reduced concurrent with the change to larger yearlings with the expectation of increased survival, which did not occur; hence recruitment was essentially reduced in these areas for the restoration program. INDEX WORDS: Lake trout, hatcheries, stocking, survival, size, Lake Michigan. * Corresponding author. E-mail: charles_bronte@fws.gov †Current address: Retired; 6698 Hwy C, Sturgeon Bay, Wisconsin 54234 INTRODUCTION Maximizing the survival of stocked fish and the efficiency of hatchery facilities has been the focus of many studies in fisheries management. This has been the case as well for the lake trout (Salvelinus namaycush) restoration program in the Great Lakes. Post-release survival has been measured for a wide variety of variables that include stocking season (Buettner 1961, Pycha and King 1967, Elrod et al. 1988), size at stocking (Pycha and King 1967), strain stocked (Eshenroder et al. 1995, Elrod et al. 1995), method of rearing (Elrod et al. 1989), and method of stocking (Elrod et al. 1993, Elrod 1997). The centerpiece of the restoration program is the annual stocking of various strains developed from donor stocks (Krueger et al. 1983, Krueger and Ihssen 1995) that originated from the Great Lakes and adjacent waters. When stocking began in the early 1960s, a target size of about 44 fish/kg was