Survival of Brook Trout from Egg to Fingerling Stage in Two Michigan Trout Streams

Abstract

Survival of wild brook trout (Salvelinus fontinalis) from the egg to the end of the first summer of life was investigated at the Hunt Creek Trout Research Station, Montmorency County, Michigan, during 1943-48, by confinement of spawners of known size and number in screened diversions, followed by direct enumeration of the resulting fingerlings. The numbers of eggs deposited were estimated from size of spawners. Percentage survival observed in six diversion experiments ranged from 4.5 to 31.7. Survival from egg to fingerling was estimated also for unconfined, natural populations in the Pigeon River and in Hunt Creek (the natural channel) during 1949-58. Consecutive fall population estimates gave the number of breeders present one fall and the number of fingerlings surviving to the following fall. Egg production for the population of breeders was estimated from egg-count data. From a series of 12 population estimates, survival rates from egg deposition to the following September ranged from 2.7 to 6.7 percent (significantly lower than in the diversion experiments at Hunt Creek). For a total of 24 observations (from confinements in diversions at Hunt Creek and Convict Creek, plus population studies on the Pigeon River and Hunt Creek), the percentage survival from egg to fall fingerling ranged from 2.7 to 43, and averaged 8.6. Excluding what appear to be unduly high results from four of the observations, the survival rates ranged from 2.7 to 8.8 percent (average, 4.7).