1. Home
  2. Research
  3. Projects
  4. Developing and testing bycatch release devices in tuna purse seiners
Project M.1.d - Developing and testing bycatch release devices in tuna purse seiners

01 Jan 2021 - 31 Dec 2023

Program(s) in charge: Ecosystem & Bycatch Program
Develop and test bycatch release devices in tuna purse seiners to improve post release survival, handling and release of sensitive key bycatch species, with particular emphasis on sharks
  • Bycatch of Endangered, Threatened and Protected (ETP) species, especially elasmobranchs, are a concern in tropical tuna purse seine fisheries
  • While the IATTC has resolutions promoting the application of best bycatch handling and releasing practices (e.g., for mobulids, sharks, turtles), there is a lack of clear guidelines for the fleet, and current release methods are quite rudimentary, often involving manual handling or basic self-made tools
  • As part of fisheries improvement projects, several fishing organizations have implemented voluntary programs to improve bycatch handling and releasing practices.
  • Associating and collaborating with experienced research institutions and fishing organizations would help explore, discuss and progress towards a reduction of bycatch mortality through the promotion of new tools that facilitate best handling and releasing practices
Relevance for management
Contributes to increase crew safety and survival of key sensitive bycatch species accidentally caught in tuna purse seiners
24 months
Workplan and status
  • Coordinate the testing of a number of novel technological devices to release bycatch species in large tuna purse seiners
  • These specific devices will be designed to achieve more efficient releases (e.g. faster, less handling stress, safer for the crew)
  • The benefits of these devices will be assessed in terms of species survival using satellite tags and other biological indicators (e.g. lactate levels, vitality indicators, etc.)
  • Collect device utilization data through IATTC observers and, scientific cruises with embarkment of AZTI/IATTC/ISSF scientists
  • Use results of the project to inform conversations during skippers’ workshops
  • Promote the utilization of the most efficient devices and methods in the region and, as appropriate, help shape recommendations
External collaborators
AZTI Foundation, the International Seafood Sustainability Foundation (ISSF) and OPAGAC
  • A report showing results from novel alternative bycatch release devices tested at sea in large tuna purse seiners
  • Dissemination material, including documents and presentations for the IATTC Bycatch Working Group, the SAC and the tuna conference.
Updated date: 01 May 2023
Progress summary for the reporting period
  • Jun-Sept 21: Discuss, decide, and build specific tools for large purse-seine vessels.
  • Sept 21-Jan 22: Develop data collection forms and protocols as well as discuss and agree the sampling design.
  • Jan 22-Apr 22: Finalize dedicated data collection forms and instructions and coordinate logistics for the first scientific cruise with a researcher from AZTI and an IATTC observer.
  • Apr 22: The first scientific cruise had to be postponed at the last minute due to issues related to COVID-19.
  • May 22: the first scientific cruise happened where 16 silky sharks were tagged.
    Jun-Dec 22: information on shark handling and releasing practices was collected on two more trips.
  • May 23: a second scientific cruise has been organized to tag sharks and take blood samples to better understand the effect of stress in survivorship of the species.
  • A third scientific cruise is expected in 2023 and project-specific observer-only data collection will also happen in additional trips.
Challenges and key lessons learnt
  • Some technological devices seem promising to improve both fishing crews’ safety and sharks post-release survival.
  • New cutting-edge promising technologies (i.e., suction discs) are currently being explored as a potential technology to be used in purse seiners.
  • Blood samples are needed to better understand the effect of stress on post-release survival of the species and develop size and fishing-operation-specific survival curves.
  • A presentation at the BYC-10 meeting.
  • A presentation at the EBWG-01 meeting.