Human impact on reef sharks studied

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MANOA, Hawaii, April 27 (UPI) -- U.S. scientists say they've completed a first large-scale estimate of reef shark losses in the Pacific Ocean -- and the news for the predators is not good.

Many shark populations have plummeted in the past three decades as a result of excessive harvesting for their fins, as an incidental catch of fisheries targeting other species, and in recreational fisheries, their study, published in the journal Conservation Biology, reported.

"We estimate that reef shark numbers have dropped substantially around populated islands, generally by more than 90 percent compared to those at the most untouched reefs," researcher Marc Nadon of the University of Hawaii said.

"In short, people and sharks don't mix."

The findings highlight the enormous detrimental effect that humans have on reef sharks, he said.

"Around each of the heavily populated areas we surveyed -- in the main Hawaiian Islands, the Mariana Archipelago, and American Samoa -- reef shark numbers were greatly depressed compared to reefs in the same regions that were simply further away from humans." Nadon said.

"We estimate that less than 10 percent of the baseline numbers remain in these areas."