Comparative study of the response of simulated temperate and tropical fish communities to fishery exploitation and environmental variability

Two simulation models of a temperate and a tropical fish community were used to compare and explore the effect of fisheries exploitation and environmental variability on the structure of the community.;The Lake Erie fish community model, a temperate system, consisted of one top predator (walleye), four secondary predators (yellow perch, white perch, white bass, and drum), and two forage groups (zooplankton and zoobenthos). The Lake Guri fish community model, a tropical system, consisted of five top carnivores (aimara, pavon, curvinata, payara and caribe) and three forage groups (two fish groups, characids and cichlids, and zoobenthos).;Fishing exploitation produced an enjuvenation effect due to the decline and loss of the largest and longest living forms in the community. Lake Erie fish community showed a surprising recovery capability, indicating the existence of only one stability domain in the presence of one top predator. In contrast, the Lake Guri fish community revealed the existence of several domains of stability induced by exploitation in the presence of various top predators at high abundances in the community.;Environmental variability induced large fluctuations in abundances of species in both fish communities. These fluctuations were larger during high exploitation than during moderate exploitation. Environmental variability did not induce shifts in the community configuration of either system.;Major implications and guidelines for the management of the fish resources of these communities were suggested: for Lake Erie, caution of introducting top predators into a relatively simple community which could destabilize the community; and importance of setting end points for species recovery programs to avoid impoverishment of the community. For Lake Guri, fishing regimes, commercial and sports, are suggested to be important means to maintain the abundances of the most valuable species in the lake; and the multiple domains of stability can be used to regulate the abundance of the top predators.