Exploitation dynamics of the Belgian beam trawl fleet targeting hotspots of flatfish

Bottom trawl fisheries, such as the Belgian beam trawl fishery targeting flatfish species, are increasingly challenged by policies, such as the landing obligation in the European Union. These policies aim to reduce the discards of fish and the physical impact of the fishing gear on the benthic ecosystem, in order to avoid irreversible ecosystem changes. In this respect, a number of fisheries management tools have been implemented to reduce the impact of the fishery on the ecosystem while ensuring its socioeconomic viability. However, all these management tools alter incentives for the fishers causing a reallocation of fishing effort in space and time. Obviously, a prerequisite for the successful implementation of any management tool is that the relationship between fishing effort and catch is predictable in space and time. Therefore, the objectives of this thesis were (i) to gain insights into how fishery dependent data at high spatiotemporal resolution can be used to predict this relationship, and (ii) to analyse how this relationship is affected by the distributional and operational characteristics of fishing fleets. Various quantitative modelling techniques were used to analyse landing and effort data of the Belgian beam trawler fleet. The results of this thesis revealed (i) the occurrence of a feedback loop between the temporal distribution of fishing effort and fish abundance, (ii) the emergence of spatial exploitation patterns with respect to the tactical decisions of fishers, and (iii) the occurrence spatial interactions between fishing vessels. These processes complicate our ability to accurately predict the relationship between fishing effort and catch in space and time and the interpretation of fisheries dependent data sources. Therefore, this uncertainty should be acknowledged in the design process of fisheries management tools.

ISBN:978-94-6357-092-3

Publication year:2018

Keywords:exploitatiedynamiek, boomkorvloot, platvis