By Kurtis Alexander
About 2,400 great white sharks troll the waters off the California coast, a new report estimates — a number that may give pause to surfers but may also ease concerns that the super predator is in danger.
A 10-person team of researchers pursued the count, published last week in the journal PLOS ONE, in the wake of earlier claims suggesting that the population of great whites in the northeastern Pacific Ocean was perilously low.
A 2011 study by researchers at Stanford University and UC Davis, published in the journal Biology Letters, estimated that fewer than 500 adults live along the continent’s western edge, igniting a debate over whether the genetically distinct Pacific white shark should be listed as endangered.
The new report finds that the great white population is not only “stable” but may be growing. Its conclusions, which were shared with regulators prior to publication, support recent decisions by the state and federal governments not to grant the animal endangered species protection.
“They still have a ways to go to get to their former levels,” said George Burgess, the director of the Florida Program for Shark Research and the lead researcher for the new report. However, “It’s our opinion as a group that the population in the eastern Pacific is getting larger.”
Burgess and his team credit the healthy numbers of great whites to decades of federal protection for marine mammals, which the sharks prey upon, as well as the shark’s classification as a prohibited species, meaning it can’t be targeted by fishermen.
The shark has historically struggled to find sufficient food as well as survive the fishing nets that are used to hunt it — and its prized fin for soup.
“It looks like this is a success story for science,” Burgess said.
Not so fast, say environmental groups that have fought to protect the shark.
The new estimate, even if correct, is still too low to ensure there are enough females to sustain the population, said Catherine Kilduff, a staff attorney for the Center for Biological Diversity, one of three organizations that petitioned to list the shark as endangered.
Great whites are relatively slow to reproduce, she noted, with females maturing at 12 to 14 years old and giving birth every two to three years to litters of two to 10 pups.
The organizations seeking endangered species status for the shark are still deciding whether to challenge the rulings against a listing.
In the meantime, Geoff Shester, California campaign director for Oceana, said his group would push for greater fishing regulations – particularly rules that seek to keep sharks from being caught accidentally as bycatch of other fish.
“We know gill nets are being placed right in the middle of these shark nurseries,” Shester said.
Counting sharks is not an easy task, which may explain why the animal’s success remains a subject of debate. The creatures move across great distances, and they don’t surface to breathe like killer whales or other marine life.
They’re also dangerous, to put it mildly. White sharks can grow to 20 feet or more, and they exhibit fierce hunting abilities that allow them to pounce upon seals and porpoises to support their weight of up to three tons.
Burgess and his colleagues didn’t manually count sharks, and they admit their numbers are estimates. The team arrived at its count by remodeling data from the 2011 study, which had been collected within the Red Triangle, the area known for great whites off the coast of San Francisco between Monterey, Bodega Bay and the Farallon Islands.
Burgess, whose team included some of the world’s foremost shark experts, said the earlier census relied too heavily on counts of sharks visiting central California and didn’t consider the number of transient creatures throughout the Pacific.
— Contact Kurtis Alexander at [email protected] Follow him on Twitter at@kurtisalexander