78 Killer Whales in Puget Sound, Numbers Continue to Decline

There are only 78 killer whales left in Puget Sound, and their numbers continue to decline.

Such frighteningly low levels have not been seen in the area - located off the state of Washington - since 1985, according to a census by the Center for Whale Research. What's more, the whales appear to be "splintering" from their pods, or social groups.

Where typically all three pods of orcas have come together in waters off the San Juan Islands during summer months, now they are dividing.

"What we're seeing with this weird association pattern is two or three members of one pod with two or three from another pod," Ken Balcomb, of the Center for Whale Research, told The Associated Press (AP). "It's a fragmentation of the formal social structure, and you can see that fragmentation going further. They are often staying miles and miles apart and not interacting.

Experts believe that a lack of food is what's driving this population decline. Killer whales (Orcinus orca) typically feed on chinook salmon passing through the San Juan Islands on the way back to Canada's Fraser River. However, the chinook population continues to fall in most areas largely because of the society's dependence on hatcheries, harvest and hydropower. While state and federal managers are trying to turn the situation around, so far their efforts have had no such luck.

Perhaps the silver lining is that among orcas, offspring tend to stay with their mothers for life. This at least sustains "matrilines," made up of young calves, their mothers and their grandmothers. Luckily, these matrilines have stayed together thus far - although the groups are noticeably smaller.

Still, orca populations have gone down from 88 in 2011 to 78 today.

According to National Geographic, orcas, which are actually the largest of dolphins, prefer cold, coastal waters, and swim as far as from the polar regions to the Equator. Pods are normally comprised of up to 40 individuals, with both resident and transient pods. Resident pods tend to prefer fish, while transient pods - which appear to be increasing, the AP reports - target marine mammals.