Overfishing has put the oceans in crisis. The global population of sharks and rays has been reduced by half since 1970, and one third of these marine species is at risk of extinction, according to a study published in the journal Science.
The population of sharks, rays, and chimaeras (cartilaginous fish similar to sharks) decreased by 64.8% since 1951, according to the study covering 1,199 species worldwide.
Ocean Crisis
The catches of these animals doubled between 1950 and 2000, going from 750,000 kilograms to 1.5 million tons. In 2020, between 33.3% and 37.5% of shark and ray species were at risk of extinction, compared to 3.5% in 1970.
This decline affects the functioning and balance of marine ecosystems, as sharks are key predators, and their decline disrupts the food chain. Additionally, some sharks transport nutrients between ecosystems.
Rays also play an important role, mixing and oxygenating sediments while searching for food, benefiting other species living in these sediments. Furthermore, they contribute to carbon storage.
Zones of Hope and Solutions
Researchers have identified “hope spots” where shark and ray populations are in better conservation status, such as Australia, Canada, the United States, New Zealand, and some regions in Europe and South Africa.
Colin Simpfendorfer, from James Cook University in Australia, points out that nations can reduce the risk of extinction by decreasing fishing pressure to sustainable levels, strengthening governance of fishing areas, and eliminating harmful subsidies.
Initiatives and Projects
The study was conducted under the Global Shark Trends Project (GSTP), involving the International Union for Conservation of Nature (IUCN), Simon Fraser University in Canada, James Cook University, and the Georgia Aquarium in the United States.
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