Environmental Variability and the Stability in the Outcome of the Professional Fishery in Lake Ijssel, the Netherlands

Abstract

Fishermen experience natural variability through variations in their annual catch per species. In Lake IJssel the catches of pikeperch, Stizostedion lucioperca, in 101 mm gillnets show the largest variability, compared with the variability in the catches of perch, Perca fluviatilis, in these nets and of eel, Anguilla anguilla, in fykenets. Variability in recruitment is the major cause of annual variation in the catch of pikeperch and perch. Year-class strength of pikeperch is highly correlated with summer temperature. Effort limitation provides a marginal gain in stabilising the annual catch in the Lake IJssel pikeperch and perch fishery. In spite of severe over-exploitation, the total outcome of the Lake IJssel fishery has been stable over the last decade, because of the low variability in the catches of eel and because all together four species are exploited.