Abstract
The annual production (P) of Orconectes virilis between the summers of 1976 and 1977 in Dock Lake was 52.5 kg/hectare. The annual P/ ratio was 1.8, while the mean biomass () was 28.7 kg/hectare. On nearby Shallow Lake during the same time period the annual production was 43.8 kg/hectare. The annual P/ ratio was 1.5 and the mean biomass was 29.6 kg/hectare. Compared to several similar Michigan lakes (surface area 1.4‐1.9 hectare) annual production and mean biomass values are lower in the Ontario lakes (surface area 1.2‐1.6 hectare). The crayfish in the Ontario lakes have a faster growth rate, earlier age at maturity, and higher mortality rates. The P/ ratio compares to those recorded for other species and regions of the world. Thus far annual P/ ratios reported in the literature vary from 0.5 to 2.0.

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