Karmactive Staff
The marine ecosystem faces an unprecedented crisis as shark and ray populations have plummeted by more than half over the past five decades, according to a global study published in Science. The research presents the stark reality of systematic depletion while offering practical solutions for species recovery.
The paper offers a comprehensive analysis revealing that overfishing has decimated populations of chondrichthyan fishes—sharks, rays, and chimaeras—by over 50% since 1970. “In addition to intentional targeting and bycatch, the threat to sharks is compounded by habitat degradation, climate change, and pollution. The result is that over one-third of chondrichthyans now face the threat of extinction,” states Professor Colin Simpfendorfer from James Cook University, co-author of the study.
The research includes the development of an aquatic Red List Index (RLI) for comprehensive assessment of these species.
Professor Nicholas K. Dulvy from Simon Fraser University, the study’s lead author, describes a concerning pattern: “The sequential depletion of the largest and most functionally important species—such as sawfish and rhino rays—was followed by the decline of large stingrays, eagle rays, angel sharks, hammerheads, and requiem sharks. Eventually, fisheries turned to deep-water sharks and skates for the liver oil and meat trade.”
The decline represents more than mere population statistics. As apex predators, sharks maintain marine ecosystem balance through complex food web interactions. Reef sharks contribute to the nutrient dynamics of coral reefs, while rays help oxygenate sediments, supporting marine productivity.
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In response to these alarming trends, some nations, including Australia, Canada, New Zealand, the United States, a few Europian nations, and South Africa, have constituted effective conservation strategies, which include:
- Science-based fisheries catch limits
- Strengthened governance frameworks
- Elimination of harmful fishing subsidies
- Measures to minimize incidental catch
However, there are widespread issues in fisheries management, particularly in regions with weaker governance structures. Chronic underassessment and inadequate management continue to threaten species recovery efforts.
Professor Simpfendorfer emphasizes the clear path forward: “Nations can reduce the extinction risk by lowering fishing pressure to sustainable levels, strengthening fisheries governance, and eliminating harmful subsidies.”
