A review of the sharks and rays in the Mediterranean has shown that over 40% are at risk, making this group one of the most threatened populations in the world.
The overview of cartilaginous fishes in the Mediterranean by Rachel Cavanagh and Claudine Gibson for the World Conservation Union (IUCN) found that of the 71 chondrichthyan (sharks, rays and skates) species 30 are threatened and only 14% aren t at risk at all.
The IUCN Red List is a globally recognised scientifically based source of information on the status of plants and animals based on their life history, ecology, distribution, habitat, threats and population trends. Species are classified as Critically Endangered, Endangered, Vulnerable, as well as Near Threatened, Least Concern and Data Deficient.
Species found to be either Critically Endangered or Endangered in the Mediterranean sea included Shortfin mako shark and Porbeagle shark, White and sandbar sharks, Maltese skate, three species of angel sharks and the endemic Giant devil ray which can grow up to six metres long.
Sharks, rays and skates are often at the top of the food chain. They are long living with low reproductive rates and long gestation periods (sometimes longer than that seen in elephants). This means that the consequences of the wide ranging threats experienced by these species are far reaching as there is no rapid population growth.
This study found that the most serious threat to sharks was fisheries. This included overfishing for species such as dogfish, rays, smoothhounds and catsharks; bycatch eg. being caught on the lines used for tuna and swordfish, and bottom trawling altering the ocean floor habitats needed for both predator and prey.
In addition it was found that there was degradation of nursery and spawning grounds by industrial pollution, and a knock on effect where pollution accumulates at the top of the food chain resulting in species such as the spiny dogfish containing illegally high levels of mercury, organochemicals and trace metals.
Throughout the Mediterranean there are no limits on fished species of cartilaginous fish with only eight species of shark listed in conservation conventions and only three species actually protected.
Sonja Fordham, Deputy Chair of the SSG and Policy Director for the Shark Alliance is reported as saying in Science Daily Never before have Mediterranean countries had more reason or opportunity to safeguard the region s beleaguered sharks and rays.
Country officials should heed the dire warnings of this report and act to protect threatened sharks and rays through regional fisheries agreements, international wildlife conventions, and national legislation.
Such action is necessary to change the current course toward extinction of these remarkable ocean animals.
The Mediterranean Sea represents only 0.7% of the world's ocean surface area. Worldwide there are 1200 species of chondrichthyans; some species of which have seen more than an 80% decline in numbers in the last 50 years.
For more information see: Cavanagh, RD C Gibson (2007) - Overview of the Conservation Status of Cartilaginous Fishes (Chondrichthyans) in the Mediterranean Sea. IUCN, Gland, Switzerland and Malaga, Spain. vi + 42 pp.