A Two-stage Approach to Integrate Vessel Geo-tracking Data and Logbooks for Monitoring Fishing Activity of Coastal Fisheries in Waters Off Northwestern Taiwan

Abstract

Catch and fishing effort data are fundamental information to stock assessment and fisheries management, but difficult to obtain without the support of administration and sound fishery data collection system. This study integrated various sources of data from a simplified vessel geo-tracking system and logbooks from interviews with captains of coastal gillnet fisheries. We developed a two-step approach based on hierarchical cluster analysis to characterize the operation patterns and infer the fishing activities of the fishery. Results showed that the fishing effort in terms of operation duration could be estimated precisely for various vessel sizes, with catch composition and harvest information from logbooks incorporated in the analysis. We then demonstrated how to monitor the geographical extent of fishing effort and the fishing intensity by vessel size and fishing season. The method developed in this study could benefit to understand the fleet dynamics and fishing pattern, and thus could potentially overcome the difficulty regarding to fisheries management due to the complexity of operation pattern in seasonal changes on target species and various strategies to fishing.