Michigan Department of Natural Resources
Fisheries Research Report No. 2026, 1996.

Relative Growth and Survival of Three Strains of Rainbow Trout and
Three Strains of Brown Trout Stocked into Small Michigan Inland Lakes


Andrew J. Nuhfer

Hunt Creek Fisheries Research Station
1581 Halberg Road
Lewiston, MI 49756


Abstract.-The relative growth and survival was assessed over a 3-yr period for three strains of rainbow trout Oncorhynchus mykiss stocked as yearlings into two small oligotrophic lakes. Their relative tendency to emigrate was evaluated in one lake that had an outlet. The strains tested were Shasta (SH), Eagle Lake (EL), and Michigan steelhead (STT). Relative growth and survival was similarly evaluated for three stains of brown trout Salmo trutta stocked into four small, landlocked oligotrophic lakes. Brown trout strains examined were Wild Rose (WR), Seeforellen (SF), and Plymouth Rock (PR). No significant differences in survival of rainbow trout strains were found. However, point estimates of survival and standing crop in both lakes were highest for STT, intermediate for EL, and lowest for SH. EL-rainbow trout were significantly heavier than STT in four of the five samples collected over a 3-yr period from both lakes. EL trout were consistently heavier than SH in both lakes during the first 30 months after stocking. In West Lost Lake, EL were significantly larger than SH in all samples collected through 30 months after stocking, but at East Fish Lake weight differences were significant only for the sample collected ten months after trout were stocked. After 37 months residence, EL and SH in both lakes were of similar size. Overall results indicated few significant differences in growth of SH and STT. There was little evidence that any rainbow trout strain tested was more likely to emigrate from the experimental lake which had at outlet. Mean lengths and weights of WR and SF brown trout were similar during sampling periods from 6-37 months after stocking. WR and SF brown trout strains produced far more legal-sized fish (>=254 mm TL) than PR by six months after stocking because they were larger when stocked. There were no significant differences in survival or standing crops among brown trout strains after 30 months residence in the study lakes. When Ford Lake survival estimates were excluded from ANOVA analyses, survival of PR was significantly higher than for SF or WR, and survival of WR was higher than for SF after 30 months residence. After 30 months residence there were no significant differences in standing crops among brown trout strains.