Deep-water sharks join the ranks of species facing extinction, together with polar bears and the hippopotamus, listed on the World Conservation Union’s 2006 Red List of Threatened Species. The World Conservation Union (IUCN) Red List, released on 2 May 2006 in Switzerland, is the world’s most authoritative inventory of the conservation status of animals and plants.
It underlines the ongoing decline of the earth’s biodiversity, and man’s impact on life on earth – and in our oceans. (1) Once believed to be resilient to extinction, today marine species are disappearing at a faster rate than their terrestrial counterparts. IUCN and partners recently launched the Global Marine Species Assessment (GMSA) in order to obtain a more comprehensive view of the state of conservation of marine species, particularly commercial fishes and invertebrates. This year saw the first comprehensive regional assessment of selected marine groups and the picture is far from encouraging for the ocean’s large marine animals, which top extinction risk categories. (2) “The IUCN Red List findings underline the plight of many species throughout the world’s seas and oceans, from the Mediterranean to Chinese coasts. Animals that are part of our heritage and have been around since the age of the dinosaurs are now going down the drain,” warned Carl Gustaf Lundin, Head of the IUCN Global Marine Programme. (3) Sharks and rays (Chondrichthyes) were among the first marine groups to be systematically assessed and the biggest marine group to go onto the Red List this year. Of the 547 species listed, one fifth are threatened with extinction. (4) This confirms suspicions that these mainly slow-growing species are exceptionally susceptible to over-fishing and are disappearing at an unprecedented rate world-wide. Deepwater sharks have a naturally low biomass, and are limited by the low productivity and geographic constraints that define their cold, deepwater environment. These factors combined with the limited reproductive capacity of all sharks (often even lower for deepwater species) cause deepwater sharks to be particularly vulnerable to fishing pressure.
In the past, sharks and rays were discarded, but today they are purposefully targeted for their fins and meat, and are under serious threat from a combination of destructive fishing practices, including high seas bottom trawling. They are also caught as bycatch – fishers in deepwater areas cannot avoid catching deepwater sharks alongside other fish species, due to their diversity and widespread nature. Gulper sharks comprise a group of about 16 widespread, mainly bottom dwelling deepwater species. They are believed to be among the most biologically vulnerable of all sharks meaning that even low levels of incidental catch can dramatically reduce populations. For example, the gulper shark (Centrophorus granulosus), caught by trawls, line gear and gill nets, has declined by 80-95% in its main range within the Northeast Atlantic and is now listed as Vulnerable. Although this species has not been reviewed globally, recent regional assessments show that it is at increasing risk. (5) The Australian endemic Harrison’s dogfish (Centrophorus harrissoni) has undergone an even more dramatic decline of over 99% in two decades, fuelled by demand from the fisheries and cosmetics industries. (6) The International Council for the Exploration of the Sea (ICES) advised zero catch of depleted deep-sea sharks in November last year. According to David Griffith, General Secretary of ICES, “Deep-sea fish… are long-lived, slow reproducing fish that can withstand only low levels of fishing pressure. All our evidence indicates that the current fishing pressure on these stocks is much too high. We are particularly concerned about deep-sea sharks such as the Portuguese dogfish and leafscale gulper shark, which are now heavily depleted.”
“Marine species are proving to be just as much at risk of extinction as their land-based counterparts: the desperate situation of many sharks and rays is just the tip of the iceberg,” said Craig Hilton-Taylor of the IUCN Red List Unit. Deep sea species in general tend to be slow-growing and highly vulnerable to disturbance. Deep sea bottom trawl fishing vessels operating in international waters, drag huge nets across the sea bed at depths of up to two kilometres, crushing everything in their path, including important cold water coral habitats. The nets weighted with steel plates and heavy rollers can even drag up cold-water coral branches and rocks, along with huge quantities of bycatch that may include sharks, rays and as yet undiscovered species. “Ultimately, removing species at the top of the food chain will impact on each and every one of us as eliminating predators has a ‘domino effect’ on other animals and species we most frequently put on our plates,” said Lundin. “As human beings, we can only point the finger at ourselves,” notes Sarah Fowler, Co-Chair of the Shark Specialist Group of the IUCN Species Survival Commission (SSC), “We are the ones driving amazing creatures to extinction.”
“The 2006 IUCN Red List shows a clear trend: biodiversity loss is increasing, not slowing down,” said Achim Steiner, Director General of the World Conservation Union (IUCN). “The implications of this trend for the productivity and resilience of ecosystems and the lives and livelihoods of billions of people who depend on them are far-reaching,” he said. (11) Mr. Steiner, soon to be appointed Executive Director of UNEP, in his current post as IUCN’s Director General has called deep sea bottom trawling an act of insanity and said “We must protect the high seas before it’s too late”.
Notes: (1) Release of the 2006 IUCN Red List of Threatened Species reveals ongoing decline of the status of plants and animals (2) 2006 IUCN Red List brings to light underwater giants’ downfall; ray of hope for some marine marvels (pdf) (3) See (2). (4) 2006 IUCN Red List of Threatened Species: Marine facts & figures (pdf) (5) Marine Red List Case Studies (pdf) (6) See (2).