The southern resident population of orcas is down to less than 100 individuals.| Photo: NOAA

With just 81 individuals left, a population of killer whales (a.k.a. orcas) local to the West Coast has been listed as a federally Endangered species since 2005. Now, new data on the beleaguered whales' habits is prompting a wildlife protection group to ask for better protection of orca habitat along more than half the U.S. Pacific coast -- including more than a third of the California coast.

In a petition filed Thursday with the National Marine Fisheries Service (NOAA Fisheries), the Center for Biological Diversity (CBD) is asking that the agency dramatically expand its designated critical habitat for the southern resident orcas to include a 47-mile-wide band of ocean along the entire coast from the Olympic Peninsula to Point Reyes north of San Francisco Bay.

The whales' current critical habitat is restricted to the whales' summer habitat in the Puget Sound area. But new telemetry data indicates that southern resident orcas venture as far south as the Marin County coast, where they gather off the mouths of coastal streams to feed on salmon. And human activity from water pollution to ocean noise threatens the orcas' ability to feed along the coast.

"These whales somewhat miraculously survived multiple threats over the years, including deliberate shootings and live capture for marine theme parks," said CBD attorney Sarah Uhlemann, a senior attorney at the Center for Biological Diversity in a press release. "But we can't expect orcas to thrive once again if we don't protect their critical habitat."

Orcas, toothed whales known to science as Orcinus orca, may be the most widespread whale species on the planet, with a range spanning all oceans from pole to pole. The fiercely intelligent species seems to be in the process of evolving into a few distinct groups, and taxonomists debate whether to divide orcas up into as many as five new species. There are the so-called "transient" orcas, which travel in small bands and feed mainly on marine mammals such as sea lions. There are "offshore" orcas, about which little is known: they can gather in groups of a few hundred and likely subsist on schooling fish, though they may also feed on sharks and marine mammals.

And then there are "resident" orcas, the most intensively studied, which live in matrilineal family groups (pods) and mainly eat fish and squid. They exhibit distinct dialects in their complex vocalizations; females are thought to select potential mates based in part on whether the male's dialect is different from hers. As differences in dialect between pods parallel how closely the pods are related to one another, such a preference for a sexy foreign accent may help to limit inbreeding.

The Southern Resident population of orcas consists of three pods, denoted by biologists as "J," "K," and "L," each made up of orcas related through by maternal descent. Members of the K and L pods regularly travel from Puget Sound and the Strait of Juan De Fuca to forage along the Oregon and California coasts: telemetry from individuals in each of those pods in the first seven months of 2013 shows that the K and L pods came within a stone's throw of the San Francisco Bay Area. Southern Resident orcas will eat chum and coho salmon, as well as herring and rockfish, but they strongly prefer the larger Chinook salmon, which may make up as much as four fifths of their diet.

And that means that protecting California salmon and their offshore habitat may well be crucial to the health of two of the Southern Resident orca's three pods, especially in a drought year that may be devastating to California's Chinook population. Southern Resident orcas may already be feeling the effects of drought, as well as other factors depleting fish stocks off the Pacific coast. Only two calves were born to the population in 2012, and 2013's sole new calf died before the year was out.

"Killer whales are important to the identity and spirit of the Pacific Northwest, and beloved by people across the country," said Uhlemann. "If this population of amazing, extremely intelligent animals is going to survive for future generations, we need to do more to protect their most important habitat."