Australian scientists say coral reef shark populations on the Great Barrier Reef are in a catastrophic collapse.
Research -- conducted by William Robbins and colleagues at James Cook University and the Australian Research Council's Center of Excellence for Coral Reef Studies -- found grey reef shark numbers have declined to around 3 percent of unfished levels and are falling so quickly they could collapse to 1-1,000th of unfished levels within 20 years.
The study is the first of its kind to combine direct underwater counts of shark abundance with mathematical models that project future population trends.
"Our research indicates current reef shark abundances and levels of fishing pressure are simply not sustainable," said Robbins, the study's lead author. "Reef sharks are effectively on a fast track to 'ecological extinction' -- becoming so rare that they will no longer play their part in the ecology and food web of the reef.
"It also suggests that immediate and substantial reductions in fishing pressure will be needed to give threatened populations any chance of recovery," he added.
The research appears in this week's issue of Current Biology.
Copyright 2006 by United Press International
Explore further: Unsafe levels of toxic pollutants in heavily fracked Ohio county