SEATTLE (AP) — A small barrel roll gave Washington whale watchers a gender reveal over the weekend and reason to be hopeful about a pod of endangered southern resident orcas that frequent Puget Sound.

The Center for Whale Research confirmed that the J pod’s newest calf, J58, is a female after the 6-month-old calf was seen rolling onto her back, allowing researchers to determine the gender, SeattlePI.com reported.

The calf was born last September to J41 near Vancouver, British Columbia.

It was the second orca born that month, with the first, born to Tahlequah, confirmed to be a male. Tahlequah raised international concern in 2018 when her calf died and she carried it for 17 days and more than 1,000 miles (1,609 kilometers).

The new female is a promising sign as the sustainability of the population depends on viable females.

Orcas remain in close association with their mothers for life, and pods usually center around older female members. Reproductive age for female orcas ends at around age 40, according to Orca Network.

The Center for Whale Research confirmed that the total southern resident population was at 74 at the end of 2020, comprising all three pods. The birth of a new calf in the L pod last month brought the population to 75. Whether that calf is female or male has not been confirmed.

Threats to their survival include boat noise and vessel disturbance; pollution; and lack of food, especially chinook salmon.