Potential for Exploitation of Freshwater Crayfish in Coolwater Systems: Management Guidelines and Issues

Crayfish species found in coolwater systems are relatively long lived. They have slow to moderate growth, low fecundity, and low juvenile survival rates, making them poor candidates for intensive aquaculture. However, these characteristics make them well adapted to the pulsed food regimes and low energy inputs characteristic of high latitudes. The high economic cost of enhancing nutrient/temperature regimes of high latitudes through intensive culture techniques makes harvest the most effective alternative for using most wild stocks. Because changes in growth and fecundity in response to exploitation are limited, finfish models are inappropriate for development of management guidelines for crayfish fisheries. Age-specific mortality rates are the most important mechanisms adjusting population size when stocks are exploited. Coolwater crayfish populations appear resilient, self-regulating, and capable of producing sustained, moderate yields. As long as habitat remains intact, removal of 50% of the adult population is possible with little danger of growth or recruitment overfishing. To maintain a high yield-high recruitment situation, the most desirable tactic for a trap fishery may be to harvest without sex or size restrictions, provided that harvesting each year begins after females release the young. The major obstacle to exploitation of these crustaceans will likely be the development of suitable markets, rather than any limit on their productivity.