A female orca from the endangered southern resident killer whale population off the West Coast is considered missing and may be dead, according to U.S. researchers that monitor the group.

J14, a 42-year old female from J-pod, who has three living offspring and is also a grandmother, was last seen at the beginning of August, the Centre for Whale Research said in a news release. 

J14, who is also known as Samish, was born in 1974.

Ken Balcomb of the Centre for Whale Research last saw J14 on July 31, and she "gave no indication of being sick or otherwise unhealthy." 

The whale research centre said another staff member photographed the whale from shore on Aug. 3.

Since the last July sighting, the organization has had three on-the-water encounters with J pod, but J14 was not present.

The research centre said it will have to wait for one more definitive encounter before it officially records her as deceased.

The southern resident orca whales' population has been in decline for several years. Last year however, the group did experience somewhat of an orca baby boom, with eight calves being born.

The southern resident killer whale population is made up of 84 killer whales living in three different pods in the Salish Sea off the south coast of B.C. and the north coast of Washington state.