Common wisdom holds that a glimpse of the oceanic whitetip shark is a rare one. Researchers say the shark, which lives in tropical water like the Gulf of Mexico, has never been very abundant.
But, as NPR's John Nielsen reports, a new study tells a very different story. As recently as 50 years ago, the whitetip may have once outnumbered all the other big fish in the gulf, according to a paper published in Ecology Letters.
In the 1950s, fishermen in the Gulf of Mexico thought the whitetip was scarce because it was never seen in open waters. But a study of marine life done at the time, uncovered recently by one of Ransom Myers' students at Dalhousie University in Nova Scotia, portrays a different picture.
Federal researchers dragged long lines studded with thousands of hooks back and forth across the gulf. The data added up to a population 300 times more abundant than the current one, says Myers.
Myers then read other studies from the 1950s. They indicated that at the time, the whitetip was common in tropical waters all over the world.
What amazes him, Myers says, is that a species that may have once outnumbered the American bison population at its height could fall so far so fast.
Researchers don't know what happened. Myers suspects that many died tangled in fishermen's long lines; others died when their fins were cut off by fishermen feeding the bottomless Asian market for shark fin soup.
Fishermen and government scientists have been critical of Myers' work, saying the fishing logs he used aren't reliable. But they do agree that, today, there are fewer big fish in the sea.
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