Report: Great White Shark Population Off California Is Growing
Friday, June 27, 2014
Photo by Sharkdiver.com / Wikimedia Commons
Shark researchers found the population is much larger than previously thought and does not warrant further protections. Great white sharks have been protected in California since 1994 and in the U.S. since 2005.
More than 2,400 great white sharks are thriving off the California coast, according to a new report.
A team of shark researchers, including Cal State Long Beach marine biology professor Chris Lowe, found the population is much larger than previously thought and does not warrant further protections.
A 2011 study, conducted by UC Davis and Stanford University researchers, stated the population of white sharks and subadult white sharks near Ano Nuevo Island and the Farallon Islands off California was 219, prompting environmental groups to petition for the predator to be listed as an endangered species.
“White sharks have been protected in California since 1994 and protected in all federal water since 2005,” Lowe said. “And it’s really been since the early 2000s that we’ve started to see this uptick.”
Lowe said the shark’s recovery can also be attributed to increased protections of marine mammals, a great white’s favorite meal, and the fishery industry — fewer pups are dying in nets.
“Since the Marine Mammal Protection Act in 1973, and better fisheries management and regulation of commercial fisheries, we’ve seen marine mammal populations really skyrocket,” Lowe said.
He said the biggest indication of the shark's increase comes from the commercial fishing records.
"Despite the fact that fishing pressure has been substantially reduced over the last 20 years, the number of little white sharks incidentally caught in some of these commercial fisheries and recreational fisheries has been increasing," Lowe said. "However, most of the sharks are released alive and those sharks we know now will survive."
Lowe uses two tagging tools to track adult and juvenile great whites.
“Acoustic telemetry requires us to catch a shark," he said. The researchers then surgically implant into the shark a transmitter that has a battery life of 10 years. “Then we have listening stations, underwater listening stations, all along the coast,” he said.
Lowe's other method is satellite transmitters.
“Every time the shark comes to the surface we can actually get a position of where the shark is,” he said.
Lowe said the tracking devices have helped him identify hotspots where great whites spend some of their time.
“There seems to be a hotspot in Santa Monica Bay, there seems to be a hotspot off Ventura, there seems to be a hotspot off San Onofre.”
He said San Diego’s waters provide a nursery ground for 5-foot-long harmless newborns. The pups are often drawn close to shore to feed on stingrays and fish.
“We’ve had several sharks, up to four sharks, go in and out of Los Angeles Harbor,” Lowe said. “And we suspect the reason why they’re doing that is because when they’re born they’re naive. Their moms leave them, they have to learn how to hunt on their own and we suspect that they’re looking for places where there’s readily abundant prey that are easy to catch.”
The pups' 20-foot-long parents prefer a meal of seals and sea lions. Lowe assured that La Jolla’s pinniped population of 300 isn’t large enough to lure adult predators to the region.
“Those are a drop in the bucket compared to what you find along the Central California coast or along the offshore islands,” Lowe said.
The two main population centers for adult great white sharks is the Farallon Islands off of San Francisco and Mexico’s Guadalupe Island.
Lowe said people should be excited and not worry about the great white shark population increasing because it could be one of California’s greatest conservation success stories.
“It’s a sign that we’re doing things better,” Lowe said. “And despite the fact that we have three times more people living in coastal California now than we did 40 years ago, the fact that all these populations are showing signs of increase in the last 40 years is a sign that we can fix some of the problems that we’ve created. "
To view PDF documents, Download Acrobat Reader.