Bioeconomic Regime Shifts and Management of Lake Fisheries Invaded By Rusty Crayfish

Over the last 40 years, as Rusty Crayfish have invaded many inland lakes in Wisconsin and Michigan, USA, some lakes have experienced long-term low abundance of crayfish and little ecosystem change, while in other lakes, high abundance of crayfish and many undesirable ecosystem changes have occurred. Intermediate abundances of crayfish have been transitory. Where crayfish have become abundant, populations of submerged vegetation, invertebrates, and some fishes decline, causing economic losses. Crayfish interactions in the foodweb are complex—including reciprocal intraguild predation with some sportfish species—which may contribute to whether a lake tips from the low crayfish regime to the undesirable, high crayfish regime. The biological system interacts with management actions with reciprocal feedbacks that determine bioeconomic shifts and equilibria. Recent empirical and theoretical work on biological and economic feedbacks support the following conclusions. Weak institutions can eliminate tipping points so that only undesirable states of the world exist. Institutions of intermediate strength interact with ecological relationships to determine the existence and nature of tipping points. Strong institutions that account for feedback responses create the possibility for desirable regimes and can cause undesirable regimes to cease to exist.