Conservation groups petition to protect West Coast populations
By Summit Voice
SUMMIT COUNTY — Recent studies suggest that populations of great white sharks off the West Coast of the U.S. have dwindled well below previous estimates, leading conservation groups to call for Endangered Species Act protection for the apex predator of the ocean.
In a formal petition to the National Marine Fisheries Service, a trio of environmental groups outlined threats to the sharks, including high mortality from gillnets used to catch other fish. The petition is based on 2011 studies suggesting that adult and sub-adult great white sharks may number as few as 350 — far fewer than researchers expected, presenting an inherently high extinction risk.
Other studies have shown that sharks are also accumulating high levels of DDT and PCBs in their livers.
Federal biologists will examine the information in the petition to decide whether endangered or threatened species status is warranted. If they agree, they would propose a listing, subject to extensive public review and comment, along with an economic impact analysis.
A listing could include a critical habitat designation that could help resource managers protect and recover populations.
The groups — Oceana, the Center for Biological Diversity and SharkStewards — also plan to ask for protection under California’s Endangered Species Act., claiming that the sharks are on the brink of extinction because of its small 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 program 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 U.S. West Coast are part of the northeastern Pacific population, genetically distinct and isolated from all other great white sharks around the globe.
The continued existence of white sharks is hampered by their low reproductive output, slow growth rate, late maturity and high mortality rates during the first year.
Great white sharks are a critical part of the ocean ecosystem, playing an important top-down role in structuring the ecosystem by keeping prey populations in check, like sea lions and elephant seals. The presence of great white sharks ultimately increases species’ stability and the diversity of the overall ecosystem.
Deadly gillnets capture and kill great white sharks. Gillnets 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 — targeting California halibut, white seabass, thresher sharks and swordfish — may be responsible for more than 80 percent of the young white sharks caught in their nursery grounds. These fisheries have very low observer coverage, meaning the gillnet bycatch is probably under-reported.
“The fierce great white shark is no match for gillnets, which are like curtains of death for marine animals,” said Catherine Kilduff, attorney for the Center for Biological Diversity. “There are so few of these majestic sharks left in our waters, they urgently need protections.”
Young great white sharks off the Southern California coast are also found to have the second-highest documented mercury level of all shark species 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.
An Endangered Species Act listing would help protect the sharks from key threats and garner funding for research to better understand the status and threats to this distinctive population of sharks.
Filed under: biodiversity, endangered species, Environment, Marine biology, ocean conservation Tagged: | California, Center for Biological Diversity, endangered species, great white sharks, marine conservation, national marine fisheries service, sharks