Levy trajectories of Peruvian purse-seiners as an indicator of the spatial distribution of anchovy (Engraulis ringens)

Analogous to other top predators foraging on patchy resources, the spatial behaviour of fishers provides information on the spatial organization of fish. Focusing on the Peruvian anchovy purse-seine fishery, vessel monitoring system data are used to describe fishing vessels' trajectories, and acoustic survey data to characterize anchovy spatial distribution. Vessel trajectories were analysed in terms of move-length distribution, whereas fish distribution was characterized by spatial extent, concentration, and fractal dimension. Fishers perform Levy flights that can be characterized by a single statistic (mu); mu is significantly correlated with the fractal dimension of fish distribution. It is argued that the Levy statistic is a good candidate for an ecosystem indicator that might contribute to realtime monitoring of ecosystems. (c) 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.