Electronic monitoring for improved accountability in western Pacific tuna longline fisheries

Christopher J Brown,Amelia Desbiens,Max D Campbell,Edward T Game,Eric Gilman,Richard J Hamilton,Craig Heberer,David Itano,Kydd Pollock

doi:10.1016/j.marpol.2021.104664

Abstract

The collection of accurate fisheries catch data is critical to ensuring sustainable management of tuna fisheries, mitigating their environmental impacts and for managing transboundary fish stocks. These challenges are exemplified by the western Pacific tuna longline fishery, who’s management includes >26 nations, but is informed by critically low coverage of fishing activities by scientific observers. The gap in observer data could be filled by electronic monitoring (EM), but there are few trials that span multiple nations. A large-scale trial of EM systems on tuna longliners based in Palau, Federated States of Micronesia and the Republic of the Marshall Islands, is reported on. Comparisons are made of catch rates of market and bycatch species in corresponding EM, logbook and human observer data. Retained species were under-reported in logbooks by up to three times and discards of many species were not reported in logbooks. Discards identified in the EM data included threatened species such as marine turtles. Catch rate estimates from EM data were comparable to those estimated by human observers. EM data recorded a higher species diversity of catches than logbook data. Analysis of the EM data indicated clusters of bycatch that were associated with specific fishing practices. These results suggest further expansion of EM could inform improved management of both target and bycatch species. Ultimately greater coverage of EM data could contribute to reconciling debates in international stock allocation schemes and support actions to reduce the impacts of the fishery on threatened bycatch species.

Highlights

Fisheries management authorities rely on accurate catch records to determine controls on fishing effort, determine appropriate license fees, and to manage environmental impacts on bycatch species
Collecting accurate catch data for the highly migratory species caught in tuna fisheries poses additional challenges, because tuna fisheries operate over large areas, are at sea for long durations and often fish across multiple exclusive economic zones (EEZ)
The highest rate of under-reporting for the presumed target tuna was for yellowfin in Palau and Republic of the Marshall Islands (RMI)

Summary

Introduction

Fisheries management authorities rely on accurate catch records to determine controls on fishing effort, determine appropriate license fees, and to manage environmental impacts on bycatch species. Regional assessments of endangered, threatened and protected species (e.g., [7, 8]) are not representative of all fleets and geographies, so their findings may be misled by biased data inputs [9]. It is unknown how much catch is discarded, whether the catch locations reported in logbooks are accurate, or how much catch is transhipped at sea [10]. Insufficient catch data is impeding environmentally sustainable management of the fishery and may compromise the management of stocks that are rapidly adapting their distributions in response to a changing climate [11]

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Results

Conclusion