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article imageCoral reef decline linked to overfishing of sharks

By Michael Thomas     Sep 20, 2013 in Environment
A simple case of cause and effect may be why the world's coral reefs have been trending towards decline. According to a new study, the killing of too many sharks is also killing the population of herbivorous fish that keep reefs healthy.
According to Australian and Canadian scientists, led by the Australian Institute of Science (AIMS), removal of sharks from the temperamental ecosystems causes what's known as a "cascade effect." When a predator at the top of a food chain is removed, an explosion in the population of mid-level predators occurs, and the newly-enlarged population in turn kills the smaller fish that help to keep coral reefs in good shape.
The study, which will be published in the September 28 issue of the journal PLOS One, monitored Scott Reef and Rowley Shoals, an area 300 km of the northwest Australian shore that Indonesian fishers regularly visit.
"Going by our surveys, around four sharks a day were being taken from these reefs," Mark Meekan, principal research scientist at AIMS, told the Guardian Australia. "This doesn't sound like a lot, but it has been going on for a long time. The fishermen come in their sailing prows, which can dry an awful lot of shark fin on the decks."
According to the Guardian, a staggering 100 million sharks are killed per year.
Research into what's hurting the coral reefs is coming at an opportune time, according to Science Daily. The reefs have been facing heavy pressure from both human activity and climate change.
"Given that sharks are in decline on reefs worldwide, largely due to the shark fin trade, this information may prove integral to restoration and conservation efforts," said Jonathan Ruppert, a University of Toronto PhD student involved with the study.
The Guardian also notes that the population of reef sharks within the Great Barrier Reef has shown a very marked decline, despite a third of the reef being declared a "green zone" that protects sharks from human predators.
More about Coral reefs, Sharks, Australia, Fish, Overfishing
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