By Victoria Cavaliere
SEATTLE (Reuters) - The first calf born in two years to an endangered killer whale population off the coast of the Pacific Northwest has been declared missing and presumed dead just weeks after its birth, experts said on Tuesday.
The mother of the baby orca was seen for three days in a row swimming in the waters off Washington state without her calf at her side, a sign it was dead, said Howard Garrett, co-director of the Washington-based Orca Network.
"For the first two years, a calf is glued to its mother's side. This calf hasn't been seen with its mother, and that's conclusive that it died," Garrett said.
The baby was born in early September, the first since 2012, and was a hopeful sight for whale experts who have seen the number of orcas in ocean waters off the Pacific Northwest fall to some of their lowest levels in history.
There are 78 orcas in the region, down from 98 in 1995 and historic highs in the 19th century of over 200, Garrett said. The population was declared endangered in 2005.
Experts had given the baby orca between a 50 percent and a 65 percent chance of survival.
The largest members of the dolphin family, orcas are highly social and intelligent marine mammals that communicate using whistles and pulsed calls and maintain group cohesion or "pods" through their lifetime, according to the National Oceanic and Atmospheric Administration (NOAA).
Threats to the population include pollution and overfishing of their major food source, chinook salmon, near the San Juan Islands in the Salish Sea.
The whales also have been hurt by vessel noise and military exercises using sonar, artillery and bombs that can upset their underwater communications and foraging behavior, according to the Center for Whale Research.
(Reporting by Victoria Cavaliere, Editing by Alex Dobuzinskis and Cynthia Osterman)