Guadalupe Island Conservation Fund :: Shark tracked to Cabo San Lucas

Shark tracked to Cabo San Lucas

Tag recorded movements for 90 days
By KEVIN HOWE
Monterey County Herald Staff Writer
Article Last Updated: 05/23/2007 08:24:00 AM PDT

A male great white shark exhibited at the Monterey Bay Aquarium last fall and released in January is apparently thriving in the deep ocean and behaving like a normal member of the top predator species, scientists at the aquarium reported Tuesday.

Before being let go, the shark was fitted with an electronic tag programmed to be released from the fish after 90 days.

It popped to the surface 25 nautical miles off the southern tip of Baja California near Cabo San Lucas on schedule April 15 and began transmitting stored data via satellite to scientists at the Tuna Research and Conservation Center, a collaboration between Stanford University and the Monterey Bay Aquarium.

The tag was tracked by radio and retrieved from the water on April 23 about 77 miles west of Mazatlan, Mexico, by senior aquarist Scott Reid and an international team from the aquarium, Stanford and Mexico that was hosted by Fernando Marquez of Mexico's Instituto Nacional de Pesca — National Fisheries Institute.

The device recorded the white shark's movements in the wild every 10 seconds for 90 days, and Stanford researchers spent the past month analyzing and mapping its data.

The shark swam more than 700 miles offshore and at times dove more than 1,000 feet deep during its 2,200-mile voyage, scientists found.

"It looks like the shark spent his days near the surface, with occasional deep dives to around 660 feet — a pattern typical of adults when they are traveling to and from the California coast to offshore hotspots between California and Hawaii," said Kevin Weng, a white shark researcher affiliated with Barbara Block's laboratory at Stanford University's Hopkins Marine Station in Pacific Grove.

The shark avoided surface waters at night and swam at an average depth near 250 feet, and made its deepest dives at dawn and dusk, Weng said.

After the shark's release off Point Pinos in waters around 50 degrees Fahrenheit, it quickly moved offshore to water in the 60-degree range. As it continued south, it spent time in waters as warm as 75 degrees before returning to slightly cooler temperatures around 70 degrees, Weng said.

The shark was the second kept on exhibit by the aquarium and later released into the ocean. The first great white was kept in the aquarium's Outer Bay tank for 198 days before being released into the wild in 2005.

In both cases, Weng said, the sharks "immediately engaged in active swimming patterns similar to what we've seen in the wild."

The latest shark was caught by aquarium collectors offshore in Santa Monica Bay on Aug. 17, spent two weeks in a 4-million-gallon ocean pen off Malibu, and was observed feeding in the pen before he was brought to Monterey.

The shark was 5 feet 8 inches long and weighed 103 pounds when it arrived at the aquarium Aug. 31. By the time it was released Jan. 16, it had grown to 6 feet 5 inches and 171 pounds — large enough, said Randy Hamilton, vice president of husbandry for the aquarium, that its release could have been a logistical problem and a safety risk if it was delayed much longer.

"Animals in the aquarium have gained weight a little faster than we can discern from the wild, probably because it's a little bit plush there compared to what they face in the wild," Weng said. "They get very high-quality food and probably a little more calories than in the wild."

The shark released in 2005 was tagged with an electronic device that was timed to release after 30 days, he said, and it was recovered off Point Conception in Southern California.

That shark also could have continued swimming south toward Mexico, Weng said.

The timing on this year's shark tag was set longer to provide data on a longer voyage, he said.

"The most important thing we learned from the track as a whole is that the animal made a very long-distance movement between U.S. and Mexican waters," Weng said.

The shark's international border crossing, he said, indicates that the two nations will have to collaborate on management of the great whites.

"It clearly shows that like many migratory animals, sharks don't recognize international boundaries," said Dr. Salvador Jorgensen, a postdoctoral researcher with the aquarium and the Tagging of Pacific Predators team at Hopkins Marine Station. "It underscores how important it is to work closely with our Mexican colleagues to make sure we have adequate protection for the species."

The white shark's last known position was the Cabrillo Seamount at the entrance of the Sea of Cortez.

Jorgensen said juvenile and adult white sharks have been captured inside the Sea of Cortez, but scientists don't know whether they are born there or migrate in and out.

"It's very interesting to see this juvenile show up right at the entrance," he said.

The Monterey Bay Aquarium will begin its fifth field season of white shark research later this month and will attempt to bring another young shark back to Monterey for exhibition.

"The size of the (exhibit) animal is extremely important," Weng said, adding that he and Reid captured and tagged some 3-year-old white sharks two years ago in the 350-pound range.

"Those were considered too large to be candidates for holding, so we put satellite tags on them and released them," he said. "We'll be looking for animals that are less than a year old to be held in the aquarium."

In contrast with the behavior of the two released juvenile sharks, which have tended to hug the coastline, Weng said, the tags show that the adult white sharks that appear off San Juan and A o Nuevo island make long-distance runs to Hawaii.

"We are seeing an expansion of habitat as these animals grow."

Kevin Howe can be reached at 646-4416 or khowe@montereyherald.com.





Shark fining gets national attention with this shocking report Watch Video... Learn about the science supported by GICF with this new video from RTSea Productions Watch Video... Mexico Passes Shark Finning Ban, new protections for Great White, Whale and Basking Sharks, Manta Rays. Read Article... White Shark tracked to Cabo San Lucas. Tag recorded movements for 90 days. Read Article...	Shark tracked to Cabo San Lucas Tag recorded movements for 90 days By KEVIN HOWE Monterey County Herald Staff Writer Article Last Updated: 05/23/2007 08:24:00 AM PDT A male great white shark exhibited at the Monterey Bay Aquarium last fall and released in January is apparently thriving in the deep ocean and behaving like a normal member of the top predator species, scientists at the aquarium reported Tuesday. Before being let go, the shark was fitted with an electronic tag programmed to be released from the fish after 90 days. It popped to the surface 25 nautical miles off the southern tip of Baja California near Cabo San Lucas on schedule April 15 and began transmitting stored data via satellite to scientists at the Tuna Research and Conservation Center, a collaboration between Stanford University and the Monterey Bay Aquarium. The tag was tracked by radio and retrieved from the water on April 23 about 77 miles west of Mazatlan, Mexico, by senior aquarist Scott Reid and an international team from the aquarium, Stanford and Mexico that was hosted by Fernando Marquez of Mexico's Instituto Nacional de Pesca — National Fisheries Institute. The device recorded the white shark's movements in the wild every 10 seconds for 90 days, and Stanford researchers spent the past month analyzing and mapping its data. The shark swam more than 700 miles offshore and at times dove more than 1,000 feet deep during its 2,200-mile voyage, scientists found. "It looks like the shark spent his days near the surface, with occasional deep dives to around 660 feet — a pattern typical of adults when they are traveling to and from the California coast to offshore hotspots between California and Hawaii," said Kevin Weng, a white shark researcher affiliated with Barbara Block's laboratory at Stanford University's Hopkins Marine Station in Pacific Grove. The shark avoided surface waters at night and swam at an average depth near 250 feet, and made its deepest dives at dawn and dusk, Weng said. After the shark's release off Point Pinos in waters around 50 degrees Fahrenheit, it quickly moved offshore to water in the 60-degree range. As it continued south, it spent time in waters as warm as 75 degrees before returning to slightly cooler temperatures around 70 degrees, Weng said. The shark was the second kept on exhibit by the aquarium and later released into the ocean. The first great white was kept in the aquarium's Outer Bay tank for 198 days before being released into the wild in 2005.	Donate to ongoing White Shark Research Donations will help fund valuable white shark research efforts at Isla Guadalupe. Since 2000, privately funded efforts have supported the collection of critical white shark data.
	In both cases, Weng said, the sharks "immediately engaged in active swimming patterns similar to what we've seen in the wild." The latest shark was caught by aquarium collectors offshore in Santa Monica Bay on Aug. 17, spent two weeks in a 4-million-gallon ocean pen off Malibu, and was observed feeding in the pen before he was brought to Monterey. The shark was 5 feet 8 inches long and weighed 103 pounds when it arrived at the aquarium Aug. 31. By the time it was released Jan. 16, it had grown to 6 feet 5 inches and 171 pounds — large enough, said Randy Hamilton, vice president of husbandry for the aquarium, that its release could have been a logistical problem and a safety risk if it was delayed much longer. "Animals in the aquarium have gained weight a little faster than we can discern from the wild, probably because it's a little bit plush there compared to what they face in the wild," Weng said. "They get very high-quality food and probably a little more calories than in the wild." The shark released in 2005 was tagged with an electronic device that was timed to release after 30 days, he said, and it was recovered off Point Conception in Southern California. That shark also could have continued swimming south toward Mexico, Weng said. The timing on this year's shark tag was set longer to provide data on a longer voyage, he said. "The most important thing we learned from the track as a whole is that the animal made a very long-distance movement between U.S. and Mexican waters," Weng said. The shark's international border crossing, he said, indicates that the two nations will have to collaborate on management of the great whites. "It clearly shows that like many migratory animals, sharks don't recognize international boundaries," said Dr. Salvador Jorgensen, a postdoctoral researcher with the aquarium and the Tagging of Pacific Predators team at Hopkins Marine Station. "It underscores how important it is to work closely with our Mexican colleagues to make sure we have adequate protection for the species." The white shark's last known position was the Cabrillo Seamount at the entrance of the Sea of Cortez. Jorgensen said juvenile and adult white sharks have been captured inside the Sea of Cortez, but scientists don't know whether they are born there or migrate in and out. "It's very interesting to see this juvenile show up right at the entrance," he said. The Monterey Bay Aquarium will begin its fifth field season of white shark research later this month and will attempt to bring another young shark back to Monterey for exhibition. "The size of the (exhibit) animal is extremely important," Weng said, adding that he and Reid captured and tagged some 3-year-old white sharks two years ago in the 350-pound range. "Those were considered too large to be candidates for holding, so we put satellite tags on them and released them," he said. "We'll be looking for animals that are less than a year old to be held in the aquarium." In contrast with the behavior of the two released juvenile sharks, which have tended to hug the coastline, Weng said, the tags show that the adult white sharks that appear off San Juan and A o Nuevo island make long-distance runs to Hawaii. "We are seeing an expansion of habitat as these animals grow." Kevin Howe can be reached at 646-4416 or khowe@montereyherald.com. Read original article
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