An evaluation of observer monitoring program designs for Chinese tuna longline fisheries in the Pacific Ocean using comp
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RESEARCH ARTICLE
An evaluation of observer monitoring program designs for Chinese tuna longline fisheries in the Pacific Ocean using computer simulations Jiaqi Wang 1,2 & Xiaodi Gao 1 & Jessica Chen 2 & Xiaojie Dai 1,3,4 & Siquan Tian 1,3,4 & Yong Chen 2 Received: 29 May 2020 / Accepted: 14 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This paper evaluates the performance of different observer coverage rates and 9 possible sampling designs to estimate via computer simulation the total catch of target and non-target species for Chinese tuna longline fisheries in the Pacific Ocean. The stratified random samplings include different stratification schemes (based on target species or fishing areas) with different strategies for allocating observers. The observer data from 103 vessels between 2010 and 2019 were assumed to be the “true” sampling population. We concluded that the accuracy of catch estimates had a significant positive relationship with species detectability and observer coverage rate. On average, the accuracy improved by 50% when the coverage rate increases from 5 to 20%. Current simple random sampling in Chinese tuna longline fisheries is less efficient for monitoring many species. Stratified sampling designs based on the target species tended to yield the most accurate estimates of the total catch. Allocating the observers based on the scale of the fleets in different stratum seemed to be less efficient. The proportion of observers between different fleets should be adjusted according to different monitoring objectives. In general, a large proportion of observers are recommended to be allocated onboard vessels targeting bigeye tuna (Thunnus obesus). This study has the potential to have a significant contribution to future designs of the observer monitoring programs in Chinese tuna longline fishery and many other fisheries. Keywords Observer programs . Coverage rate . Stratified samplings . Tuna longline . Pacific Ocean . Computer simulation
Introduction Mismanagement of bycatch is one of the most significant issues affecting fisheries management today. The impact of
Responsible Editor: Philippe Garrigues * Siquan Tian [email protected] 1
College of Marine Sciences, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China
2
School of Marine Sciences, University of Maine, Orono, ME 04469, USA
3
National Distant-Water Fisheries Engineering Research Center, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China
4
Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China
tuna longline fisheries in the Pacific Ocean is widespread, not only posing a threat to nearby vulnerable species but also risking the destruction of the habitats that provide the ecological basis for these complex marine ecosystems (Hall et al. 2000). Monitoring the bycatch and discards contributes to effective fisheries management and ecological and s
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