Overfishing threatens ocean sharks

Overfishing threatens ocean sharks

About 25% of oceanic shark habitats are found in active fishing grounds, according to a new international study involving 109 scientific centers. The number of these predators has not stopped decreasing due to the use of their meat for shark fin soup.

Thepelagic sharks They are those who swim in the open sea, far from the coast. They include large predators such asTiger shark, heWhite shark, or theshortfin mako, whose fishing is headed by Spain Sometimes they are caught by accident, but many others are targeted for their meat and valuablefins for the controversial Asian soup.

There is very little management of the capture of these species because the high seas are normally outside the national jurisdiction. However, for several years there has been a warning of a significant decline in many of these stocks due to overfishing. In spite of everything, the specific areas where the sharks are concentrated and the catches that are made in them remain very little known.

An international team, made up of more than 109 scientific centers from 26 different countries, includingSpain, has analyzed which areas inhabited by sharks coincide with those of high fishing activity. The objective was to know if these species can take refuge from the industry. The work is published in the latest issue of the magazineNature.

The researchers tracked the movements of nearly 2,000 sharks using satellite trackers and combined them with movement data from the vessels oflongline fishing –The type of fishing that most of these animals catch–, which they obtained through a safety and anti-collision system.

The results revealed that, on average, the24% of space occupied by pelagic sharks coincides with industrial fishing zones.

Limited shelter to avoid fishing

"The work shows that the main fishing activities in the high seas are currently focused on shark hotspots of ecological importance around the world," explains David Sims, researcher at the UK Marine Biological Association and lead author of the study. .

In the case of blue shark and shortfin mako the overlap was much greater, averaging 76% and 62%, respectively. Even internationally protected species, such as the great white shark and porbeagle, have overlap values ​​that exceed 50%.

"This indicates that the species have a very limited refuge space to avoid industrial fishing," the researcher details to Sinc. The main areas of overlap includeIberian Peninsula, heNorth AtlanticSouth AfricaNew Zealand, theAustralian Great Barrier Reef or the coast ofCalifornia, among other.

From these data, the authors developed a series of maps that can be used to assess where they can be located.Marine Protected Areasand protect areas with high concentration of species.

According to Sims, "there is an urgent need for conservation and management measures at the concentration of pelagic sharks to begin rebuilding populations."

“Some of the shark‘ hot spots ’we studied might not be there in just a few years if management measures are not taken to conserve these animals and the habitats on which they depend,” the biologist concludes.

The study highlights the potential of simultaneous satellite surveillance of sharks and fishermen as a tool for high seas management.

Bibliographic reference:

David simset al. “Global spatial risk assessment of sharks under the footprint of fisheries”.Nature (July 24, 2019). DOI: 10.1038 / s41586-019-1444-4

Video: Overfishing threatens critically endangered sharks, rays in Camarines Norte (October 2020).