Known numbers of marked F1 progeny of wild-stock rainbow trout were introduced as fall fry (1982-83) or yearlings (1984-1989) into two adjacent, small, oligotrophic, coastal montane lakes with similar low concentrations of inorganic nutrients but different morphometries (z = 2.9 and 12.5m). Survival, growth and yield were monitored by total removal and restocking. Minimum survival to age 2 was independent of size-at-stocking between 2 and 38 g, and did not vary between the two lakes. The average survival to age 2 was 42%. Instantaneous growth rates varied inversely with initial mean sizes and with initial standing crops, and were significantly lower in the deeper lake. Yield averaged 6.9 kg/ha/yr in East Twin Lake (z = 2.9 m) and 2.9 kg/ha/yr in West Twin Lake (z = 12.5 m). Power analysis of a proposed fertilization experiment indicated that four years of sampling would permit the detection of two-fold or greater yield increases with 95% power.
Johnston, N.T., Ashley, K.I. ; Tsumura, K.. 1991. Survival, Growth and Yield of Rainbow Trout (Oncorhynchus mykiss) in the Twin Lakes, Southwestern British Columbia, Prior to Lake Fertilization. Ministry of Environment. Fisheries Project Report. RD29