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Declining shark and reef fish population cause for concern says scientist

jeff@samoanews.com

Department of Marine and Wildlife Resources (DMWR) Coral Reef Ecologist Ben Carroll has voiced his concern over the shark population as well as some species of reef fish in the territory, due to low numbers and/or natural rarity and subsequent vulnerability to over-exploitation.

Samoa News had a chance to speak with Carroll about his conservation concern via-email, as he is trying bring this to the attention of the public before the upcoming Coral Reef Task Force meeting which will be held in American Samoa.

“Sharks have existed in the world’s oceans for hundreds of millions of years. However, in more recent history, shark numbers in all oceans around the world have declined drastically, with some species suffering reductions of more than 90% of their population. Unfortunately, the same is true in American Samoa where a recent study found that reef shark densities are currently only 4-8% of what they once were,” said Carroll.

According to Carroll, the greatest threat facing sharks is fishing, and many shark species are being overfished, meaning they are being killed faster than they can reproduce. He went on to say that sharks are directly targeted for their meat, liver and other products as they are also caught incidentally or accidentally while fishing for different target species.

“Perhaps the most disturbing practice of all is shark-fining which involves the removal of the sharks fins and the discard of the rest of the shark, while often still alive, at sea,” he said. “Sharks are vulnerable to over-exploitation due to their biology, as they are a relatively long lived species with slow growth rates, a late arrival at sexual maturity (20 years or more in some species) and low birth rates.”

He went on to say that, concerning coral reef fish, there are a few coral reef fish that have similar biology to sharks and are relatively slow to reproduce. This coupled with the fact that these fish species are naturally rare, makes them especially vulnerable to over-exploitation through minimal fishing pressure.

“For example, the bump-head parrot fish (Bolbometopon muricatum) which naturally occurs in low numbers may have had its population further reduced by fishing pressure, as this species is a particularly easy target for spear-fishermen, especially at night. In American Samoa it has only been observed a handful of times in hundreds of surveys over the past eight years.”

Another rare species, the Maori wrasse (Cheilinus undulatus) is also an easy target for fishermen. Both of these species are in trouble in most parts of their natural range and are therefore listed on the IUCN Red List of Threatened Species,  and are both also listed as Species of Concern by the U.S. National Marine Fisheries Service.

“These issues, along with others affecting our coral reef resources, will be addressed at the upcoming Coral Reef Task Force Meeting to be held here in American Samoa from August 17 -23,” said Carroll.



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