Walrus: Two Tonne Tusker (S33E08)

Eighteen-year-old Sivuqaq, a vibrant captive Pacific walrus, should have been a father by now, but circumstances haven’t favored him. Enter reproduction scientist Holley Muraco, who is determined to tackle the toughest challenge of her career: helping Sivuqaq become a parent. However, understanding walrus romance proves to be elusive; even pandas have been bred with greater success. Holley believes that the key to unraveling this mystery lies in studying Sivuqaq's wild relatives. To find the answers, she sets off on an expedition to their breeding grounds in Northern Alaska.