Michigan Department of Conservation
Institute for Fisheries Research Report No.1741, 1967
Mortality and Production of Brook Trout and Rainbow Trout Planted in East Fish Lake, Michigan
Gaylord R. Alexander and David S. Shetter
Abstract.-We studied survival, growth, angler exploitation, and production from five consecutive matched plantings of brook trout and rainbow trout (8.5-9.5 inches long) in East Fish Lake, Montmorency County, Michigan, 1958-1962. The 16-acre lake received 300 of each species each year. Rainbow trout survived at nearly 100% from planting time in October to the following fishing season in April, whereas brook trout averaged only 49%. Most mortality of brook trout occurred between 15 October and the date of ice formation (approx.15 Dec.). Brook trout stayed in shallow water along shore more than did rainbow trout. Loss of trout was attributed to various predators. Of control trout held in wire enclosures, few died. Anglers caught 86% of the rainbow trout which were planted, but only 39% of the brook trout. For each pound of trout planted, anglers caught 3.59 lb. of rainbow trout, but only 0.76 lb. of brook trout. In addition to the five-fold better return on a poundage basis, the rainbow trout provided a fishery throughout the 4-month angling season, whereas nearly all brook trout were caught during the first 10 days. The brook trout grew well, but the rainbow trout did better-up to 1.5 lb. per year. An even greater poundage return on rainbow trout would accrue if the beginning of the angling season were delayed somewhat, to take better advantage of the spring growing season.