NOAA 10-Year Study Shows Orca Whales Still on the Decline

In the decade since Pudget Sound's orca whales were protected under the Endangered Species Act (ESA), scientists behind a NOAA-led study reported Wednesday that these animals are still struggling to recover.

Scientists are "trying to understand ... why the whales haven't increased more than they have," Mike Ford, director of the Conservation Biology Program at NOAA's Northwest Fisheries Science Center, said, according to The Seattle Times.

The report, based on data collected over the last 10 years, revealed that Pudget Sound orcas are among the most contaminated marine mammals due to pollutants, the Associated Press (AP) reported.

The three biggest threats contributing to their decline are: lack of food, noise by marine vessels and pollution.

Despite recovery efforts, including a new rule preventing vessels from coming within 200 yards of any orca and designated critical habitat, the population isn't bouncing back. Scientists are now learning from the study which fish the orcas prefer to eat, how they interact with one another, as well as why their population has fallen - all factors that may be useful in helping these animals.

"We've made some significant progress in understanding each of the three primary factors of decline," Ford said, as quoted by the AP.

For the NOAA study, researchers tracked orcas with acoustic monitoring and satellite tags, following their movements during winter migration. They found that the orcas, also known as southern resident killer whales, feast mostly on Chinook salmon from the Fraser River in British Columbia during the summer.

They also eat halibut, tend to hunt less, travel more and call more loudly when vessels are nearby. This Pudget Sound population will travel as far south as Central California to forage for food and eat salmon from the Columbia and Sacramento rivers, which has high levels of banned pollutants such as PCBs.

A decade ago, there were more than 140 of these animals roaming the seas, but they declined to as low as 71 in the 1970s when these orcas were captured to be displayed at marine parks and aquariums. In 2013, they numbered at only 82.

From 2003 to 2012, NOAA spent about $15.7 million on research and conservation projects, they said.

Orcas were declared endangered in 2005, and hopefully with continued recovery efforts and information from this study, scientists can help these animals flourish once more.