Great white shark. (Photo: Oceana)
Conservation groups push to protect great white sharks
Thursday, August 16, 2012, 23:00 (GMT + 9)
Oceana, the Centre for Biological Diversity, and SharkStewards filed a scientific petition with the National Marine Fisheries Service (NMFS) in Washington DC seeking to protect the US West Coast population of great white sharks under the Endangered Species Act. This week, they will also seek protection under California’s Endangered Species Act.
New findings show the numbers of adult great white sharks off the coast of California and Baja California, Mexico are alarmingly low. This unique population is on the brink of extinction because of its low population size and the ongoing threats it faces from human activities.
“The new science set off alarm bells for all of us, as no one expected the population to be so dangerously low,” said Oceana’s California Programme Director Dr Geoff Shester. “Great white sharks are powerful allies keeping our oceans healthy, and they need us to protect them far more than we should fear them.”
Great white sharks found off the US West Coast are part of the Northeastern Pacific population, genetically distinct and isolated from all other great white sharks around the globe.
In 2011, new scientific studies by Taylor Chapple et al and Oscar Sosa-Nishizaki et al produced the first population estimates of West Coast adult and sub-adult great white sharks, together totalling fewer than 350 sharks-- far lower numbers than researchers expected, presenting an inherently high extinction risk. The continued existence of white sharks is also hampered by their low reproductive output, slow growth rate, late maturity, and high mortality rates during the first year.
Deadly gillnets capture and kill great white sharks, and are presently the leading threat to their survival. While their direct capture for sale is prohibited off the coasts of California and Mexico, young great white sharks are killed as incidental bycatch in commercial fishing.
Set and drift gillnets--which together target California halibut, white seabass, thresher sharks and swordfish--are responsible for over 80 per cent of the reported young white sharks caught in their nursery grounds. These fisheries have very low observer coverage, meaning more white sharks are caught than what is reported.
“The fierce great white shark is no match for gillnets that are like curtains of death for marine animals. There are so few of these majestic sharks left in our waters, they urgently need protections,” said Catherine Kilduff, attorney for the Centre for Biological Diversity.
Young great white sharks off the Southern California coast are also found to have the second highest mercury level on record for any sharks worldwide, six times higher than levels shown to cause physiological harm to other ocean fish species. In addition, these sharks had the highest levels of the contaminants PCB and DDT in liver tissue observed in any shark species reported to date globally.
“These majestic predators are vital for the health and balance of our ocean ecosystems,” said David McGuire, Director of SharkStewards. “Even the removal of one sexually mature individual from a population this small can have serious impacts on the population as a whole. They need stronger protection immediately.”
An Endangered Species Act listing will afford the sharks protections from key threats and garner funding for research to better understand the status and threats to this distinctive population of white sharks.