Seeking the secret to walrus reproduction vallejo Researchers are seeking to learn the secrets of walrus reproduction

Jocko belly-flopped onto the artificial ice floe in the middle of his Vallejo pool and rocked back and forth - a blubbery portrait of walrus bliss.

His counterparts in the wild should have it so good. Their Arctic ice floes are shrinking because of global warming, which means their numbers could decrease.

That possibility makes the breeding behavior of Jocko and his two female friends, who live at Six Flags Discovery Kingdom, fascinating to scientists - to the point that one researcher is creating an artificial vagina to entice the 2,200-pound Pacific walrus into sexual acts that can be measured and quantified.

"This would be the first semen sample out of a walrus in the wild or captivity," said Holley Muraco, a specialist in marine mammal reproduction who has constructed similar body parts for horses, cows and pigs.

She said the dramatic changes likely to occur in the Arctic would affect walrus breeding, an obscure activity about which little is known, partly because it happens underwater and partly because Pacific walruses live in a remote part of the world.

"It's extremely mysterious," Muraco said. "They're very inaccessible. But we're able to study the Six Flags walruses so intimately, and they participate so fully, that we can apply that science to wild animals if we need to."

If researchers can understand and demystify walrus sex, their findings will shed light on how environmental change can influence the conditions that hurt or help breeding.

Visitors peek into the walrus exhibit at Six Flags Discovery Kingdom. Visitors peek into the walrus exhibit at Six Flags Discovery Kingdom. Photo: Paul Chinn, The Chronicle Photo: Paul Chinn, The Chronicle Image 1 of / 7 Caption Close Seeking the secret to walrus reproduction 1 / 7 Back to Gallery

The 14-year-old Vallejo residents - who are already sexually active but have nothing to show for it - are among only 30 or so captive walruses divided among seven facilities in the United States. The Discovery Kingdom animals offer unusual access because they arrived at 2 weeks of age as unrelated orphans from the Bering Sea, and were raised and trained by humans.

The walruses' mothers had been killed during a subsistence hunt. The pups were given Yupik names suggested by Eskimo schoolchildren: Uquq (blubber), Siku (ice) and Sivuqaq (the ancient name for the village of Gambell, Alaska), who was dubbed Jocko in the movie "50 First Dates."

Jocko, still growing, could reach 4,000 pounds, while the females are about 1,700 pounds apiece and gaining steadily. Like other members of their species, they are gregarious, surprisingly agile and prone to blowing snot on whatever or whomever is nearby.

"They want to feel what you're wearing with their whiskers and they want to breathe in your nose," said Discovery Kingdom animal trainer Robert Roozendaal on Tuesday, as the three walruses inspected a visitor to their indoor quarters. "It's a walrus greeting."

Jocko, described as exceptionally mellow and laid back, ate ice cubes and sucked on his tongue. Siku, an overachiever and the "honor roll student" in the group, slid into the pool, while the lazy but assertive Uquq did sit-ups.

"A lot of animals have personality, but these guys are so interactive they can express that personality with more animation," Roozendaal said.

Toni Rael, another animal trainer at the Vallejo theme park, said polar bears have gotten most of the attention in the uproar over global warming, while walruses have been overlooked - although the Center for Biological Diversity, a conservation group, sued the U.S. government in December to force it to add the Pacific walrus to a list of threatened species. A census is now under way, but there are no hard numbers for the elusive creatures.

"They're an underappreciated marine mammal," Rael said. "But it's funny how they capture your heart."

Sweet, lovable creatures

Ron Schusterman, a research marine biologist at UC Santa Cruz, has been studying the sounds of the walruses at Discovery Kingdom since they were babies.

"They're so lovable," he said. "They truly are. They want to snuggle up to you all the time. Of all the animals I've worked with, they're the coziest. They love to rub and touch. They're just very sweet animals that right now need protecting."

Schusterman has scrutinized a vast repertoire of walrus vocalizations that include whistles, groans, bellows, grunts, knocks, taps and metallic bell sounds. He said he hopes that the Vallejo pinnipeds, who provided vocals in "Jurassic Park" and the "Lord of the Rings" trilogy, will soon reproduce.

"It's very important that the animals in captivity should be bred if at all possible," he said. "It's a good way to make a contribution to the environment. We know so little about them."

Although the ice floe in the Six Flags pool was built out of surfboard material, it is treated like the real thing by Uquq, Jocko and Siku, who has no tusks because they became infected when she was younger. The white object is their favorite hangout, said Leah Coombs, marine mammal supervisor at Discovery Kingdom.

In the wild, Coombs said, ice floes are crucial because Pacific walruses, not known as marathon swimmers, can rest on them, give birth on them and follow them during a lengthy migration from summer in the Chukchi Sea to winter in the Bering Sea.

With fewer ice floes, the easily spooked herd animals retreat to rocky shores, where the calves are sometimes trampled to death by the adults when something frightens them and they take off en masse.

Coombs is excited about the reproduction study. "Nobody has figured it out yet," she said of walrus sex.

Destructive and dirty

Captive walruses are rare because they are difficult to acquire, given the many rules and regulations, as well as very destructive and dirty, said Michael Muraco, animal director at Discovery Kingdom.

"It's very expensive to manage them," he said. "And they're like an elephant. A lot of the food that comes in comes right back out."

His wife will monitor the walruses' hormones, use ultrasound, determine when the females cycle during the winter breeding season and watch them mate under water - in addition to making the latex or rubber artificial vagina into which semen can be deposited when Jocko ejaculates.

"They're not shy with their sexuality," Holley Muraco said. "So we'll try to put the pieces of the puzzle together and see why we don't have a baby yet."

For more pictures and a video of the walrus exhibit at Six Flags Discovery Kingdom, go to sfgate.com.