Lately, the Alaska SeaLife Center in Seward has been fairly successful at getting its aquatic animals pregnant. Earlier in May, thousands of giant Pacific octopus eggs laid more than a year ago by “Lulu” began to hatch. Now, scientists at the center announce they've successfully bred two Steller sea lions.
Last summer, the scientists facilitated the breeding by housing three female sea lions -- Eden, Tasu and Sitka -- in the same habitat as Woody, a 20-year-old male. Recent ultrasound examinations confirmed two of the females are pregnant. Tasu and Eden are both 13 years old. The remaining female, 7-year-old Sitka, did not get pregnant, according to a SeaLife Center press release.
Scientists have reported that the two pregnant sea lions are carrying normally developing fetuses with healthy heart rates, they’re remaining cautious.
“Because wild Steller sea lions often mate within two weeks of giving birth, females are pregnant and lactating the majority of their lives,” Dr. Lori Polasek, a marine mammal scientist at the center and an assistant professor at the University of Alaska Fairbanks, said in the press release. “If we want to understand this endangered population, it is important to study nutritional and physical demands on a female that is pregnant and supporting a nursing pup at the same time.”
If everything goes according to plan, she said, the pups will be born early this summer, and researchers anticipate breeding the lions again in 2013.
According to the center, the pregnancy studies complement research completed over the past 16 years, including the Chiswell Island video monitoring project that has closely followed reproduction of wild Steller sea lions on an island 35 miles south of Seward, a small city of about 2,800 located along Resurrection Bay on the Kenai Peninsula.
Stellers are the largest of all sea lions, and they have an appetite to match. These giant fin-footed mammals hunt fish, squid, octopus and, rarely, smaller seals. They’re found off northern Pacific coasts from Japan to California, according to the National Geographic Society.
The animals are social and gather at various times throughout the year when not mating. Even in crowds, the large bulls are unmistakable -- they are three times larger than females.
But their breeding habits are one of nature’s great mass spectacles. The lions invade their favorite beaches, or rookeries, blanketing the landscape. Young pups are sometimes crushed by competitive males, who must hold their territory on the beaches in order to breed, according to National Geographic.
Typically, sea lions mate in June when males and females gather on the rookeries, and pups are born about a year later, the SeaLife Center scientists said. The scientists will continue to monitor Tasu and Eden with ultrasound, but predicting the pups’ birthdates is difficult due to limited information about the animals’ pregnancies, said Brett Long, the center’s husbandry director.
To mimic what would occur in the wild, preparations are underway to allow Woody to mate with the same three females again this summer after the pups are delivered. At 20, the 2,396-pound Woody is old for a breeder. But his pampered life at the center has helped Woody remain active and healthy. Still, Woody’s retirement from the breeding program is set for fall 2014, Long said.
Jerzy Shedlock can be reached at jerzy(at)alaskadispatch.com