Purse Seine

Description

Global shark populations have declined by about 50% over the past 50 years, largely due to fishing, including accidental capture in tuna fisheries. While small sharks can be handled relatively safely, large adult sharks—critical for reproduction—are difficult and dangerous to release, often leading fishers to leave them on deck until they are near death. Older release methods (like tail ropes) were banned due to injury risks.

To address this, AZTI developed two safer release devices (a padded “shark velcro” and “shark harness”) that allow quick, less harmful lifting and release. Early tests showed promising survival results, but sample sizes were too small for firm conclusions. This new pilot project will expand testing through fisher training, onboard trials, and satellite tagging to assess post-release survival.

If proven effective, these devices could improve shark survival, enhance fisher safety, support sustainable fishing practices, and help fisheries meet conservation standards.

Description

Oceanic shark populations have declined sharply over the past 50 years, largely due to fishing. In tropical tuna purse seine fisheries, vulnerable  and critically endangered sharks are commonly caught as bycatch around fish aggregating devices (FADs). Handling these sharks on deck is dangerous for fishers and harmful to the animals, often leading to injuries and poor survival outcomes.

To address this, AZTI developed slide systems that allow sharks to be released directly back into the water with minimal handling, improving safety and survival. Trials with customized slides, along with the introduction of shark-bite-resistant gloves, aim to further reduce risks. The project includes gear development, training, data collection, and collaboration with fleets to promote adoption.

Expected outcomes include safer working conditions, improved shark survival, wider adoption of release tools across fleets, and potential integration into fisheries regulations—ultimately supporting shark population recovery and more sustainable fisheries.

Description

Mobulid rays (manta and devil rays) are highly vulnerable and now endangered due largely to fishing impacts, especially from tuna purse seine fleets where they are accidentally caught. Current release methods are slow, stressful, and often harmful, leading to high mortality—even when rays are alive upon capture. Research shows that releasing them within three minutes can boost survival rates to up to 90%.

A new solution, the “sorting grid,” developed by AZTI, allows tuna to fall through while retaining large rays, which can then be quickly lifted and released with minimal handling. This method is safer for crews and significantly reduces stress and release time for the animals.

The grids have already been successfully adopted by Spanish and U.S. fleets. This project aims to expand their use to other fleets through gear development, training workshops, at-sea trials, and data collection. Results will be shared to encourage wider adoption and integration into fisheries regulations. Overall, the initiative seeks to improve survival rates of mobulid rays, support their population recovery, and enhance the sustainability of fisheries.