Halifax, Canada, Feb 10: Shark populations are in steep decline in the northwest Atlantic because of overfishing, scientists report.
Even the great white, the fearsome star of the film jaws, is under threat, according to a new study. Fishing records showed that populations of several shark species had fallen to less than a quarter of their former size.
Most affected was the hammerhead, whose numbers were down by 89 per cent since 1986. The white shark, also known as the great white, had declined by 79 per cent. Since the early 1990s, no white sharks had been reported in two zones off Nova Scotia and Newfoundland and very few off the united states eastern seaboard.
Populations of thresher sharks had fallen by 80 per cent, tiger sharks by 65 per cent, and blue sharks by 60 per cent. With the exception of the Mako shark, all the species studied had declined by more than 50 per cent in the past eight to 15 years.
Julia Baum and colleagues from Dalhousie University in Halifax, Canada, wrote in the journal ``Science``: ``Our results show that overfishing is threatening large coastal and oceanic sharks in the northwest Atlantic.
``The large and rapid declines we document are in addition to substantial historical reductions. Over-exploitation of Elasmobranchs (sharks, skates and rays) is known to have already nearly eliminated two skate species from much of their ranges. The magnitude of the declines estimated here suggests that several sharks may also now be at risk of large-scale extirpation.``
Pelagic longlines used by fishermen to target swordfish and tuna in the northwest Atlantic were largely to blame for the dwindling numbers of sharks. The lines stretch up to 40 miles or more with numerous baited hooks attached along their length. They are notorious for indiscriminate fishing, and have caused the death of numerous turtles and sea birds.
The researchers pointed out that being near the top of the food chain, shark numbers have a marked effect on marine ecosystems. They warned that current conservation plans will not be enough to stop the sharks` decline, and called for extra protection on a par with that given to vulnerable populations of sea turtles and tuna.
Bureau Report
