Spoilt for choice? Linking individual fishing behaviour with fleet dynamics

Abstract

Much progress has been made in developing a precautionary approach to fisheries management, however in most cases, this has been largely confined to biological elements and a more balanced application needs to address social and economic risks as well. A current challenge for global fisheries governing bodies is to manage fishing capacity so that it is commensurate with the availability of the resource. Fisheries science is by its nature an interdisciplinary field, and combining information has proven to be increasingly important in achieving sustainable fisheries management. One factor of increasing importance is the ability to anticipate fisher behaviour in response to management regulation, in order to reduce the unanticipated side effects of management actions aimed both at the fishery sector and at other sectors. The primary aim of this work is to improve understanding of fisher behaviour to support fisheries management. Statistical modelling tools were applied to determine the relative importance of, and improve understanding of, selected drivers for both short term and long term behavioural responses to fishery management measures, to quantify the relationships between capacity, effort and fishing mortality and to investigate spatial competition with other marine sectors. The results demonstrate that expected revenues from target species, experience or habit, management measures, fuel prices, aggregate activity and maritime traffic are significant factors in determining fisher decision-making on when and where to fish. Some of the unobserved random components of the model causing heterogeneity in the selection of fishing grounds by fishers could be attributable to individual variations in decision-making, along with other factors such as skipper skill, age, nationality and vessel attributes. Detailed individual-level vessel data that take into account the heterogeneity and dynamics of a beam-trawl fishing fleet were analysed to draw linkages between capacity, effort and fishing mortality. These relationships could be developed for use as indicators for spatial and temporal management. A key finding from this study was the detection of a switch in species targeting and fishing efficiency over time, with an estimated 6.2% annual decrease in plaice (Pleuronectes platessa) and an estimated 0.6% increase in sole (Solea solea) over the 11-year study period. The research demonstrated how knowledge of drivers of fisher behaviour can lead to better understanding of responses of fishing fleets to management and how more detailed information on fleet structure and dynamics (including effort and capacity) improves knowledge of the relative contributions of different components of a fleet to fishing mortality.