According to a new research study, designed to systematically assess the global fate of sharks and rays, approximately one quarter of all cartilaginous fish across the globe face extinction within the coming decades. The research study was published in the journal eLife and expanded upon previous investigation into local fishing practices, involving populations of sharks and rays.
IUCN Red List Shows Rays and Sharks are Threatened
The study was performed by the International Union for Conservation of Nature’s (IUCN’s) Shark Specialist Group (SSG). The organization is co-chaired by Nick Dulvy, the Simon Fraser University Canada Research Chair in Marine Biodiversity and Conservation in British Columbia.
Although prior research has established that local fishermen were over-exploiting populations of sharks and rays, the latest study was the first to explore their status across coastal seas and oceans. Over the course of two decades, the authors utilized the IUCN’s Red List of Threatened Species – the world’s most definitive database on the conservation status of biological species – to assess the current standing of over 1,000 species. Using the vast knowledge of the IUCN inventory, a series of workshops – involving over 300 experts – assimilated the following information on each of the species:
- Abundance and distribution
- Population patterns
- Catch, threats and conservation attempts
Ultimately, the survey found that 249 species of the shark, ray and chimaera (a.k.a ghost sharks) species, out of a total of 1,041 recorded species, were allocated to three threatened categories on the IUCN Red List. The authors found that 107 species of rays and 74 species of sharks faced extinction; around a quarter of all species investigated were classified as “Least Concern.”
Sharks and rays are considered at higher risk of extinction than numerous other animals and were shown to comprise of the fewest number of species that were regarded as being “safe.” In looking at the worst affected regions for dwindling numbers of sharks and rays, the authors concluded that the Red Sea, the Mediterranean Sea and the Indo-Pacific had the hardest hit marine ecosystems.
Fisheries and Destruction of Marine Ecosystems Trigger Population Declines
Dulvy, acting as co-author of the latest paper, recently reflected on his team’s findings during a press release. Dulvy singles out sharks and rays inhabiting shallow waters as being placed at the greatest risk, since these areas are frequently targeted by fisheries.
In particular, sharks are often killed to produce shark fin soup – a remarkably popular serving of Chinese cuisine, typically reserved for banquets and other special events. Acquisition of the ingredients – excised from the pectoral, caudal and dorsal shark fins to make the soup – is estimated to lead to the death of millions of sharks, annually. A bowl of shark fin soup can sell for a handsome price of $200, per bowl, throughout Asian restaurants. All in all – according to a recent survey of global shark populations, performed by the Pew Environment Group – India, Indonesia, Mexico, Spain and Taiwan appear to be the top countries for landing the most sharks.
Dulvy also mentions that the combined impact of habitat degradation, and over-exploitation of populations of sharks and rays, are most severe for 90 of the threatened species identified in freshwaters. He then ruminates over the future of these threatened species, in the absence of conservation efforts:
“A whole bunch of wildly charismatic species is at risk. Rays, including the majestic manta and devil rays, are generally worse off than sharks. Unless binding commitments to protect these fish are made now, there is a real risk that our grandchildren won’t see sharks and rays in the wild.”
The group believe a loss in the afore-mentioned shark and ray populations would be tantamount to losing chapters of evolutionary history, since they are the “… only living representatives of the first lineage to have jaws, brains, placentas and the modern immune system of vertebrates.” Absence of some of the largest, predatory species could also have a cascade effect on entire marine ecosystems.
In the future, the IUCN’s Shark Specialist Group would like to see governments implementing policies that are designed to protect sharks, rays and chimaeras. To achieve this, the organization suggests a complete clamp-down on groups catching the most threatened species, the safe-guarding of vital habitats and the implementation of scientifically determined quotas for fisheries.
By James Fenner