Scientists and fishers have teamed up to find a way to save manta rays
Summary: Thousands of at‑risk manta and devil rays become accidental bycatch in tuna fishing nets every year. A simple sorting grid could help save them.
The Bycatch Crisis
Every year, commercial tuna fleets in the Atlantic, Pacific and Indian oceans trap more than 200,000 rays in their longline and trawl gear. These large, slow‑moving fish are often mistaken for target species because they share similar habitats and can be mistaken for tuna or swordfish at a distance. The result is a steady loss of mature manta and devil rays, many of which are already listed as vulnerable or endangered. Scientists estimate that bycatch mortality could reduce population sizes by up to 30% over the next decade, threatening the ecological balance of reef ecosystems.
Innovative Sorting Grid
Researchers from the Marine Conservation Institute and the University of Hawaii have engineered a lightweight, modular “sorting grid” that can be installed on the outer frame of a trawl net. The grid features a series of angled slats that redirect larger, non‑target species—such as rays—away from the net’s mouth and into a separate, easily recoverable chute. Field trials in the Gulf of Mexico have shown a 70% reduction in ray bycatch without compromising tuna catch rates. The grid’s design uses buoyant, corrosion‑resistant materials that can withstand the high‑pressure environment of deep‑sea fishing.
Collaborative Approach
Key to the project’s success has been the partnership between scientists, local fishers, and industry stakeholders. Fishermen who participate in the trials receive training on grid installation and maintenance, and are offered a share of the cost savings from reduced gear damage. In return, they provide real‑world data on grid performance and help refine the design. This collaborative model not only accelerates adoption but also builds trust between conservationists and the fishing community, a critical factor for long‑term sustainability.
Looking Ahead
With the grid’s promising results, the next step is to scale deployment across major tuna‑fishing regions. The team is working with the International Trawl Association to incorporate the grid into standard gear regulations, and with the U.S. Department of Commerce to offer subsidies for early adopters. If implemented globally, the sorting grid could reduce manta and devil ray bycatch by an estimated 60%, giving these species a fighting chance to rebound and preserving the health of marine ecosystems worldwide.