The magnificent black and white predators were first seen off Half Moon Bay, where they were apparently searching for salmon, which are declining in numbers in the Pacific Northwest.

Photos were taken Jan. 24 of from nine to 15 orcas swimming in the open water between the Farallon Islands and San Francisco.

Although killer whales have been seen off the coast before, researchers believe some five dozen or more individuals are now regularly leaving their historic habitat in the Puget Sound area for the abundant waters near the Golden Gate.

"It's exciting for us because they traveled so far to get to California, which means they can travel farther than people thought to find food," said Nancy Black, a marine biologist and whale expert for Monterey Bay Whale Watch. "Before, it was just transient (orcas) that have been seen in Bay Area. This is something unusual."

Ken Balcomb, senior scientist and founder of the Center for Whale Research, which has tracked the pod in Washington for 30 years, said the whales, including a mother and calf, were positively identified through the photos as members of a family group called "K-pod."

Based on observations made a little over a week earlier off Half Moon Bay, Balcomb believes that members of "L-pod" are also in the vicinity. If they are, it would mean that as many as 63 whales could be spread out over 30 miles around the Farallones.

The animals make up two of the three pods of the southern resident killer whale population, which provide thrills every summer for whale watchers in the Pacific Northwest as they follow salmon toward the rivers where the fish spawn.

The southern resident whales, so-named because they are the southernmost group of orcas in the Pacific Northwest, have been documented along the Central California coast five times before, starting in 2000, scientists say. The sightings this year were seen by whale experts as confirmation that the orcas have extended their habitat.

"This is the first time we've noticed this as a recurring activity on this scale," said Kelley Balcomb-Bartok, Balcomb's son and the spokesman for the whale research center. "It extends their range 1,000 miles."

The presence of the highly social species off the Golden Gate may be great news for whale watchers, but it's not such a good thing for fishermen, who see it as an indication of how few salmon there are left off Washington and Oregon. Salmon fishing was severely limited along the coasts of the two states and California last year because of a huge drop in the number of chinook and coho salmon in the Klamath River.

Experts believe the orcas are undoubtedly looking for salmon off the California coast, where the runs in the Sacramento and San Joaquin River systems were not so depleted, like in the Klamath. The addition of killer whales into waters already teeming with the fish-loving seals and sea lions could spell the further decline to a fishery already impacted by water diversions and habitat destruction.

"You get a pod of killer whales feasting on salmon -- that could create another problem," said Zeke Grader, executive director of the Pacific Coast Federation of Fishermen's Associations. "I don't want this to be a red herring that distracts people from the fact that we need adequate water flow and better conditions for migrating fish in the rivers, but even if we resolve the Klamath issue, there may not be this abundance of fish because of these other factors."

The killer whale, or Orcinus orca, is the largest species of the oceanic dolphin family and is found in all the world's oceans. Males can reach up to 31 feet long and weigh 8 tons. They are one of the fastest marine mammals, reaching speeds of up to 35 mph. Individuals can be identified by the shape and coloration of a saddle behind the dorsal fin that is as unique on each whale as a fingerprint is on a human.

Highly intelligent and social, orcas generally travel in matrilineal family groups, but within those groups there are vast differences. Some orcas feed on seals and sea lions and others feed on other whale species. There are also transient orcas that feed mostly on sharks. None of them are considered a threat to humans.

The southern Washington orcas feed almost exclusively on fish, with chinook salmon being their favorite meal.

Their numbers have declined precipitously in the past decade because of pollution and the destruction of the historic salmon habitat, said Balcomb. They were declared an endangered species last year by the National Oceanic and Atmospheric Administration.

It is unclear whether orcas once inhabited the Bay Area. Balcomb said whale captains told him they had seen killer whales inside the Golden Gate in the 1950s when he was a federal biologist for the Golden Gate and Del Monte whaling stations.

He said there is no record of resident orcas in Northern California, but the sightings will lead to further research.