An attempt to estimate the predatory pressure exerted by the lesser weever, Trachinus vipera Cuvier, in the southern North Sea

摘要: In order to evaluate the impact of lesser weever on ecosystem southern North Sea, geographical distribution, density, growth, production and food requirements have been estimated. High densities were found around Brown Ridge, an area with high tidal current velocities, medium grain-size sediment a poor benthic fauna. Growth is restricted months June October. During winter cessation growth considerable loss weight (about 20%) takes place. Mortality has estimated by using average size frequency distribution all catches made from 1972 1984. The resulting convex type survival curve indicates rate II IV-group fishes. (estimated Allen's graphical method) population 100 individuals including age groups (0-VI) amounts 123.7 g AFDW-year‘. areas highest densities, consequently, 0.018–0.078 AFDW-m2 -year-1. With assumed transfer efficiency 10% through year, 0.18–0.78 AFDW-m 2 -year -1. Since feeds mainly fish (85.6%), almost exclusively gobies (Pomatoschistus sp.), approximately 10%, indirect predatory pressure exerted it may amount 1.6 6.7g 2.year A possible feeding pelagic organisms (calanoids, mysids) discussed.