FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 

 Table 1. — Marked lake trout released in Lake Michigan 



mission to publish information on young lake 

 trout from his collections, also to George Lunger 

 for recommendations regarding statistical treat- 

 ment of data. Photographs of the scales were 

 made by William L. Cristanelli. Scale samples 

 were taken and measurements of the fish were 

 made by Kiyoshi G. Fukano. 



MATERIALS AND METHODS 



Scales from lake trout of known age were ob- 

 tained from fish recovered during a marking 

 experiment inaugurated in 1944 as part of a pro- 

 gram for the study of lake trout in Lake Michigan 

 by the Great Lakes Lake Trout Committee.^ 



Early attempts to mark various species of fish 

 in the Great Lakes (Milner 1874; Cole 1905; and 

 others) met with small success. Most of the fish 

 were "never heard from again" after release. 

 Smith and Van Oosten (1940) reported the recov- 

 ery of 218 or 15.4 percent of 1,416 lake trout caught 

 commercially, tagged, and released between June 

 20, 1929, and August 4, 1931, in Lake Michigan 

 at Port Washington, Wis. Although Smith and 

 Van Oosten estimated the growth of the tagged 

 fish, they made no study of the scales of the re- 

 covered fish to establish the validity of the ages of 

 the fish as determined by examination of their 

 scales. 



Two later plantings of tagged lake trout in Lake 

 Michigan resulted in sparse returns. The Wis- 

 consin Conservation Department (Schneberger 

 1936) tagged and liberated 650 lake trout in Green 

 Bay during the fall of 1935. Only 13 of these fish 

 were recaptured subsequently. Three years later 

 in November 1938, Shelter ' tagged 28 lake trout 

 which were released about three-fourths of a mile 



* The committee, composed of representatives of the Great Lakes States, 

 the Province of Ontario, and the Fish and Wildlife Service, was organized 

 in 1943. It was combined with the Oreat Lakes Sea Lamprey Committee 

 in 1952 to form the Oreat Lakes Lake Trout and Sea Lamprey Committee. 

 In 1953, the functions of the coniniitlee were broadened, representation from 

 the Canadian Federal Department of Fisheries added, and the name changed 

 to Oreat Lakes Fishery Committee. 



» Tagging of Lake trout in Lake Michigan, November 7, 1938. By David 

 S. Shetter. Michigan Institute lor Fisheries Research, Ann Arbor, Mich. 

 Report No. 502 (unpublished). 



WNW by W of Seven Mile Point in northeastern 

 Lake Michigan. The following November two fish 

 from this planting were recovered within 5 miles 

 of the point of release. 



RELEASE OF MARKED LAKE TROUT 



Considerable success in the capture of marked 

 lake trout was attained from plantings made ac- 

 cording to plans of the Great Lakes Lake Trout 

 Committee. Although the original purpose of 

 these plantings was to obtain definite information 

 on the survival of hatchery-reared fingerlings, later 

 destruction of a large part of the lake trout popu- 

 lation by the sea lamprey disrupted the experi- 

 ment. Some of the marked fish were recovered, 

 however, and they form the basis for this study. 



Over a period of 3 years, the conservation de- 

 partments of Michigan and Wisconsin, participat- 

 ing with the United States Fish and Wildlife 

 Service, distributed lake trout reared through their 

 first summer in the United States Fish Hatchery 

 at Charlevoix, Mich. The plantings were made 

 each year during the first 3 weeks in September. 

 About 10 percent of the fingerlings were marked by 

 the removal of fins. Pertinent data on the mark- 

 ing and release of the young lake trout are shown 

 in table 1. Control groups of marked and un- 

 marked fingerlings were transferred each year to 

 ponds at the Michigan State Hatchery near 

 Marquette, Mich. The effect of removal of the 

 fins from these lake trout was reported by Shetter 



(1951). 



RECOVERIES 



Recoveries of marked lake trout in Michigan 

 and Wisconsin waters of Lake Michigan were made 

 by commercial fishermen, who were paid $2 for 

 each fish sent in.^ Slightly more than half of the 

 recovered lake trout were taken in chub gill nets 

 2% to 2% inches, stretched mesh; the remainder 

 were from large-mesh gill nets (4)2 inches and 

 greater) . 



8 In 1952, when numbersof the marked fish were approaching or had reached 

 legal size (Ui pounds minimum weight or larger), a $4 reward was established 

 for marked lake trout. Relatively few of these larger rewards were claimed . 



