Why a fishery data collection program?

Under the 2013 Common Fisheries Policy, the Data Collection Framework (DCF) is a set of methods designed for the collection, management, and analysis of data related to fishing activities. It aims to ensure that Member States’ fishing activities are sustainable in the long term from an environmental, social, and economic perspective.

The CFP is based on the principle that the level of exploitation of fishery resources must allow for the recovery and maintenance of stocks of exploited species above the MSY.

MSY ( Maximum SustainableYield) is the maximum amount of biomass that can be harvested on average over the long term from a fish stock, under existing environmental conditions, without affecting the reproductive process, according to a definition by the FAO (Foodand Agriculture Organizationof the United Nations).

Management measures are based on the best available scientific advice, derived from high-quality data sets. The DCF therefore proposes the implementation of a multi-year plan for the collection of fisheries data, which each Member State adapts at the national and regional levels.

Who is responsible for data collection?

In France, the DGAMPA (Directorate General for Maritime Affairs, Fisheries, and Aquaculture) is responsible for national implementation.The IRD implements this program for tropical tuna fisheries in the Indian Ocean (purse seiners and longliners).

In Réunion, it is the CITEB that is in charge of the fishing data collection program for Réunion’s longline fleet. The goal is to cover 5% of this fleet’s fishing effort in order to meet the government’s obligations to the regional fisheries management organization (IOTC —Indian Ocean Tuna Commission) and the European Union.

All data are verified, anonymized, processed, and analyzed at the IRD, which thereby enriches both the national database and that of the IOTC. This data will be used either to feed into stock assessment models or to refine existing resource management measures.

What is a longline?

The longline, or drift longline for large pelagic species, is a type of longline that is kept near the surface or at a certain depth using evenly spaced floats. The numerous hooks at the end of each line are baited with squid. It is a fishing gear used by 37% of active vessels in Réunion.Swordfish (Xiphias gladius), yellowfin tuna (Thunnus albacares), and albacore tuna (Thunnus alalunga) are the three main species caught using this technique.

Longline catches account for 81% of the average catch volume in Réunion, or 2,569 metric tons in 2023 (Source: SIH Ifremer, June 2024).

How is data collected on board longline vessels?

Through on-board observation

A qualified scientific observer closely monitors the fishing operation: the course of the fishing operation, the detailed structure of the longline and the fishing strategy, identifies and measures all species brought on board, and records all bycatch that is discarded.

It then provides a tide report with a preliminary analysis of the collected data.

Observers can also participate in research programs (tagging protected or iconic species such as sharks (project ASUR), collecting samples, and testing anti-predation devices ( PARADEP…)

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These observations are conducted on vessels in the Réunion longline fleet across all fishing areas to provide an accurate picture of overall fishing activity over the course of a year (120 sets observed annually).

Through self-sampling of fishing patterns

Captains are trained to accurately complete forms regarding fishing operations. The information requested covers fishing strategy, sea conditions, catches (commercial, bycatch, incidental, discarded, etc.), as well as any interactions with large marine mammals (sightings, captures, predation).

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Temperature and depth (TDR) sensors are also deployed on the line, allowing captains to monitor their fishing depth and enabling scientists to study the behavior of the line at depth as well as that of the species caught. Below, the behavior of a line equipped with a sensor shows a swordfish being caught at a depth of about 15 meters.

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How important are these data collection programs for fishermen? 

• – Contribution to the collective effort toward the sustainable management of fishery resources
• – A better understanding of the interactions between fishing activities and marine mammals
• – Improved accuracy of inventory estimates and fleet data
• – Gathering information on climate change andshifts in catch composition using multi-year data sets
• – Access to grants and fisheries support programs
• – Gaining insights into one’s fishing technique byequipping the line with pressure and temperature sensors
• – Commitment to sustainable and responsible fishing and eligibility for eco-certifications such as the MSC (Marine Stewardship Council)

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This map shows all the fishing trips observed (in red) and self-reported (in green) from 2006 to 2020 in the southwestern Indian Ocean, carried out by vessels from Réunion (map produced by IRD, Ob7) as part of the fisheries data collection program.

Salomé Khatib