ting the stage for the highly successful sea lamprey control program which 

 followed. This program and the ongoing lake trout restocking program, which 

 began in 1955 in Lake Michigan when about 1.3 million yearling lake trout 

 were planted, have been coordinated by the Great Lakes Fishery Commission. 

 In 1965-78, an average of over 2 million fin-clipped lake trout were planted 

 in the lake each year (data provided by the Great Lakes Fishery Commission) 

 as part of an effort to restore lake trout stocks to self-sustainability. 



By the early 1970's, the lake trout were once again considered abundant 

 in Lake Michigan and spawning activity was widespread each fall (Wells and 

 McLain 1973; Great Lakes Fishery Laboratory 1974). Nevertheless, no 

 naturally produced fingerling or older lake trout (recognizable by their 

 lack of clipped fins) have been found in the lake during routine assessment 

 sampling (Great Lakes Fishery Laboratory 1978). Therefore, little progress 

 has been made toward the goal of rehabilitating self-sustaining stocks of 

 lake trout, even though the lake contains a large population of mature fish 

 that should be ^capable of reproducing naturally. 



REHABILITATION PROBLEMS 



Following the reports of widespread spawning of lake trout in the early 

 1970's, concern deepened about the apparent failure of the fish to produce 

 surviving progeny. Numerous theories have been proposed to account for this 

 reproductive failure, including the following: 



1. Contamination of the water and fish by toxic substances such 

 as pesticides and industrial chemicals; 



2. Deterioration in bottom conditions on spawning reefs as a re- 

 sult of eutrophi cation and possibly increased sedimentation; 



3. "Abnormal homing" of planted trout as spawning adults to their 

 planting sites—generally shallow, inshore areas that offer 

 little suitable spawning substrate and are vulnerable to sedi- 

 mentation or scouring action by waves and ice; 



4. Predation on, or feeding competition with, young lake trout by 

 the now abundant, introduced species, rainbow smelt ( Osmerus 

 mordax ) and alewife ( Alosa pseudoharengus ); 



5. Artificial selection, extensive inbreeding, or physiological and 

 behavioral conditioning of hatchery fish which somehow resulted 

 in their inability to spawn successfully or to produce young 

 that are capable of surviving in the wild; and 



6. Insufficient "critical mass" or numbers of mature lake trout in 

 the lake to permit the realistic expectation of successful re- 

 production in the early 1970's. 



Various studies addressing these theories were soon initiated by the 

 Michigan Department of Natural Resources (MDNR) and the USFWS Great Lakes 



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