Sharjah24 – AFP: Overfishing has wiped out over 70 percent of some shark and ray populations in the last half-century, leaving a "gaping, growing hole" in ocean life, according to a new study.
Researchers found alarming declines in species ranging from hammerhead sharks to manta rays.
Among the worst affected is the oceanic whitetip, a powerful shark often described as particularly dangerous to man, which now hovers on the edge of extinction because of human activity.
Targeted for their fins, oceanic whitetips are caught up by indiscriminate fishing techniques. Their global population has dropped 98 percent in the last 60 years, said Nick Dulvy, the study's senior author and a professor at Simon Fraser University (SFU).
Dulvy and a team of scientists spent years collecting and analysing information from scientific studies and fisheries data to build up a picture of the global state of 31 species of sharks and rays.
They found three-quarters of the species examined were so depleted that they face extinction.
These are "the most wide-ranging species in the largest, most remote habitats on the earth, which are often assumed to be protected from human influence", the study's lead author Nathan Pacoureau.
"We knew the situation was bad in a lot of places but that information came from different studies and reports, so it was difficult to have an idea of the global situation," added Pacoureau, a post-doctoral fellow at SFU's department of biological science.
The study, published Wednesday in the journal Nature, points the finger at overfishing and weak protection, and emphasises that species can stage a comeback when conservation efforts are made.
The research focuses on oceanic sharks and rays, species that primarily live in open water. While it found variation in the health of different populations, the overall trend was clear.
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