Mauyak, a 22-year-old who is getting on in years by female beluga whale standards, has surprised Shedd Aquarium marine mammal experts by becoming pregnant.
Early this year, Shedd officials brought in an adult male beluga from out of town to place him with the three adult female belugas in its collection just in time for the beginning of the mating season.
The officials expected some mating activity this year but said they thought the animals might need a year of getting used to one another before one or more of the females became pregnant.
But the male, Naluark, 18, spent several years in the 1990s living at the Shedd, where he had mated before with all three of the females.
“We did see him mate with all three of our females, but he seemed to spend a greater amount of time with Mauyak,” said Ken Ramirez, vice president of marine mammal programs at the Shedd, after announcing Mauyak’s pregnancy Wednesday.
“Whether that was due to Mauyak seeking him out more than the other females, or him seeking her out due to some attraction he felt toward her, we don’t know.”
It is Mauyak’s fourth pregnancy. She lost two calves at birth when she lived in the Tacoma, Wash., zoo. Her third calf, Qannik, born four years ago at the Shedd, is now a healthy young male just entering beluga adolescence, spending lots of time with the Shedd’s other youngster, Kayavak, a 5-year-old female.
“We’re always cautious about the pregnancies of our marine mammals,” said Ramirez, “because so many things can go wrong. But we feel encouraged by this one, because Mauyak is an experienced mother who successfully reared Qannik.”
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Hers is the sixth beluga pregnancy experienced at the Shedd, but three of the previous five were either stillborn or died shortly after birth. Beluga gestation lasts between 14 and 16 months. Nearly six months’ pregnant, Mauyak is due to give birth next year in late spring or early summer.
Each pregnancy is a learning experience for the consortium of North American facilities that display beluga whales, Ramirez said. As keepers learn more about what is needed to successfully breed the animals in captivity, the rate of successful births has climbed, he said.
“Before we formed the consortium in 1997,” he said, “there had only been five or six successful beluga births in captivity. Since then there have been at least 12.”
That has meant the number of belugas living in captive facilities has stabilized at about 35, though keepers hope that will grow significantly with future breeding success.
“As some of the whales in our collection now are beginning to live past the life expectancies of wild belugas, we are trying to learn how long they can be actively reproductive,” said Ramirez. “We had thought that females might be too old to conceive or give birth once they’re past 25. This may well be the last pregnancy for Mauyak.”
All belugas in the consortium are treated as a single population. Because beluga males in nature only spend time with females at mating time, the consortium ships males from institution to institution for mating, according to genetic considerations.
In his youth, Naluark was the only male at the Shedd, living with several adult females. He had a dismal record as a sire until the aquarium brought in an older, more experienced male, resulting in four pregnancies within a couple of years. One, a stillborn, was Naluark’s.
“We know anecdotally that two males competing for females seems to increase the odds of getting the females pregnant,” said Ramirez.
“But when he was young, Naluark may simply have needed the guidance of an older male.”
He said Naluark probably will remain at the Shedd at least for next year’s mating season, which lasts from late winter to late spring, in hopes he will impregnate one or both of the other two adult females.