February 19, 2008
Hammerhead Shark Makes Endangered Species List
The scalloped hammerhead shark will be added to the "globally endangered" species list this year. Among the reasons are over-fishing and demand for shark fins, according to discussions that took place during last week's annual meeting of the American Association for the Advancement of Science (AAAS).
Speaking at the Boston meeting, Dr Julia Baum, a marine ecologist at the Scripps Institution of Oceanography and a member of the World Conservation Union (IUCN), said excessive fishing was putting many hammerhead sharks at risk of extinction.
BBC News reported a total of 233 shark species are currently on the IUCN Red List, with twelve classified as "critically endangered". Nine more will be added this year, including the scalloped hammerhead. Three species of thresher shark along with the shortfin mako shark are considered "vulnerable to extinction".
"Sharks evolved 400 million years ago, and we could now lose some species in the next few decades - so that would be just a blink of an eye in evolutionary time," said Dr. Baum.
She added that while concern for the sharks had been growing for many years, it was now imperative that effective action be taken to protect and restore the number of hammerhead sharks.
Material presented during last week's AAAS meeting is beginning to shed light on shark behavior, and reveal ways to best protect the shark population.
The research found that hammerhead and great white sharks inhabit fixed routes in the ocean, and gather at fixed spots around islands in the Eastern Pacific Ocean to mate and feed. The animals also move between a series of "stepping stone" sites off coastal islands between Mexico and Ecuador, as well as congregate around various undersea mountains.
Electronic tagging of 150 great white sharks off the coast of central California revealed similar findings that showed the sharks gather in "hotspots". Researchers have even named a site between Mexico and Hawaii "the white shark caf©" because of its large numbers of sharks. In a BBC News report, Salvador Jorgenson, a researcher at Stanford University's Hopkins Marine Station, said it was unclear why the sharks went there.
"They're going there to feed, or they're going there for meeting, where males and females could meet perhaps away from a feeding area, where there's less competition and more focus on mating behavior," he suggested.
Researchers believe information on shark "superhighway" routes and congregation sites can be used to help fisheries managers concentrate on protecting these areas. As a result, conservation groups are now calling for urgent measures to set limits on shark catch and fishing quotas in international waters, a practice that is now unrestricted.
They added that demand for shark fins as an expensive delicacy has also placed increasing pressure on shark populations, and are calling for a ban on the practice of shark finning, a practice where the shark's fins are removed and the rest of the animal is thrown back into the ocean to die. Hammerheads are among the most commonly caught sharks for finning, and a large shark fin can sell for over 100 dollars per kilo.
Previous research by Dr Baum's and her colleagues had shown the shark population fast declining in parts of the Atlantic Ocean, with numbers declining over 50 percent during the past 30 years in every species they studied. The drop in numbers was much greater for many large coastal shark species, with tiger, scalloped hammerhead and dusky shark populations declining by over 95%.
On the Net:
American Association for the Advancement of Science
Scripps Institution of Oceanography
World Conservation Union (IUCN)