Domeier asserts that all white sharks he has Spot-tagged have been proven to be alive after the procedure, each animal generating the satellite pings indicative of a live, swimming shark.
“The level of temporary stress we subject these fish to is unfortunate, but the scientific advancements are well worth the effort,” he wrote by email. “Our tracking data has proven these sharks quickly resume their normal behavior.”
During Domeier’s earlier white shark research at Guadalupe Island, he tagged 75 animals using handheld tagging poles. The satellite tags released from the sharks between 15 and 246 days after deployment, and 9 devices were later recovered, providing data on white shark migratory behavior. At least five of the tagged animals had swum as far west as Hawaii before returning to the Mexican island, and when Domeier and coauthor Nicole Lucas published their findings in October 2008 in the Marine Ecology Progress Series, they added substantially to the amassing scientific knowledge of the life habits and movement patterns of white sharks.
Scientists have been tracking great white sharks for years. A group called Tagging of Pacific Predators, based in Northern California, put transmitters into 179 Northern California great white sharks between 2000 and 2008 and in November published findings on the migratory patterns of the fish. Sean Van Sommeran, founder of the Pelagic Shark Research Foundation in Santa Cruz, has inserted approximately 50 identification tags and transmitters into white sharks using handheld tagging poles as they swam past his boat.
“We’ve been tagging them by hand from a boat for 15 years,” says Van Sommeran. “It’s the best way. It’s less invasive, doesn’t stress the animal, and has produced an avalanche of data. We barely touch the sharks.”
Goldman, the fisheries biologist with the Alaska Department of Fish and Game, conducted transmitter research on white sharks in the 1990s at the Farallon Islands.
“I really wonder how much more information they can get off the Spot tags than from the other kinds of satellite tags already in use that don’t require lifting this heavy fish from the water,” he says.
Mike Lever is, like Douglas, a cage-diving guide, whose vessel, Nautilus Explorer, is based in Ensenada. In 2008, Lever donated $14,000 to Domeier’s work, hoping to assist in understanding the species upon which his livelihood depends. But Lever also has doubts about the safety of white sharks undergoing Spot-tagging.
“I believe in pricking a shark with a spear and receiving tracking data for years afterward, but do we need to be hauling sharks onto boats for the same goal?” says Lever. “The big question is, Are the sharks okay afterward?”
Domeier contends that his work has been criticized unfairly, as other researchers have Spot-tagged large animals. Researchers have placed Spot tags on 400-pound salmon sharks. University of California at Davis biologists have Spot-tagged eight-foot-long hammerheads at the Galapagos. And the Tag-A-Giant Foundation, based in New York, has deployed dozens of pop-off tags onto half-ton bluefin tuna, caught on rod and reel and lifted onto the deck of a vessel.
“These very same colleagues use the exact same methods as I on other species that have similar conservation status, but for some reason it is OK,” Domeier wrote by email.
Even before Domeier began his current research, Spot-tagging had a cloudy history at Guadalupe Island. In 2006, an independent researcher, Dr. Ramón Bonfil, pulled a white shark from the water and placed a Spot tag on the animal as part of another National Geographic film project. The shark, a 16-foot female well known to the Guadalupe Island cage-diving community and nicknamed “Clytie,” has not been seen since.
Other researchers currently study great white sharks at the island. Dr. Mauricio Hoyos, an independently funded biologist from La Paz, is tracking the local movements of Guadalupe Island white sharks via acoustic tags, which are deployed with a simple stab at the dorsal muscles with a handheld lance and which emit a signal each time a tagged shark passes near a subsurface receiver. The data provided by such tags is limited — a presence or absence of the animal. Hoyos could not be reached for comment, but a field assistant, UC Davis biotelemetry grad student James Ketchum, acknowledged the great value of tracking animals across the ocean via Spot tags.
“But I don’t think they need to lift the shark out of the water,” says Ketchum, who believes Spot-tagging could cause internal injuries. “I think they could keep the shark in the water in a sling as they bolt in the tag, but what they’re doing is very sensationalist. It’s something that sells.”