New study published in PLOS ONE quantifies bycatch rates in the Maldivian pole-and-line tuna fishery

Results from IPNLF’s pole-and-line tuna fishery observers programme confirms fisheries’ low-impact nature and environmental attributes

As with other pole-and-line tuna fisheries, the Maldivian bycatch rate has been considered to be very small, but until now this has not been properly verified. To strengthen the scientific grounding of IPNLF’s work programme and support the data used to determine management practises, the IPNLF team has been working in collaboration with the Marine Research Centre (MRC) of the Maldives since August 2014 to conduct at-sea surveys of the fishery. The project was led by Kelsey Miller and guided by Dr Shiham Adam, IPNLF Director for Science & the Maldives, with the aim to observe 100 day trips of the Maldivian pole-and-line tuna fishery in order to quantify bycatch and discards, thereby identifying main factors influencing bycatch rates and to highlight any areas of concern.

IPNLF is delighted to announce that the findings from this work – one of our most comprehensive research projects to date – have been published by PLOS ONE in a new paper ‘Bycatch in the Maldivian pole-and-line tuna fishery’, authored by Kelsey Miller, Ibrahim Nadheeh, Riyaz Jauharee, Charles Anderson and Shiham Adam. This study is the first to quantify bycatch rates in the Maldivian pole-and-line tuna fishery and the influence of school association on catch composition.

In producing the report, the research team observed some 106 pole-and-line tuna fishing days, comprising 161 fishing events, during which time more than 146 tonnes of one-by-one tuna were caught. Bycatch (all non-tuna species caught plus all tuna discards) amounted to 0.65% of total tuna catch, much lower than most other commercial tuna fisheries. Most of this bycatch was utilised, so dead discards were particularly low: only 0.02% of total tuna catch. The findings also demonstrated that free school associations yield larger skipjack and less bycatch compared with associated schools (schools within one nautical mile of any FAD or other floating object or within five nautical miles of a seamount).

As well as delivering very valuable data and findings, the report offers some important suggestions to further progress the understanding of pole-and-line fishery issues and ways in which the small number of interactions with non-target species might be further mitigated.

The full report can be viewed here.

Results from these trips have contributed to other studies including IPNLF’s Technical Report on Interactions with Endangered, Threatened and Protected Species in the Maldivian Pole-and-Line Tuna Fishery