Orca pods on the move

K and L pods, the two groups of orcas that leave Puget Sound each winter, may be timing their travels in a more traditional way this year. That is, they may have departed from inland waters in December rather than waiting for the new year, as they have for the past five years. Prior to 1999, they were almost always gone before January.

"At this point, it does look like their normal travels into South Sound are over (for the winter)," said Rich Osborne of the Whale Museum in Friday Harbour. "We might get one or two visits more."

After that, K and L pods probably will be gone somewhere in the Pacific Ocean until late May or early June. That's when they typically get together in the San Juan Islands for a grand, boisterous reunion known as a "superpod." J Pod is likely to be spotted in Puget Sound occasionally throughout the winter. The travels of all three Puget Sound pods, totalling 89 animals, have grown in importance since 2001, when the whales were proposed for listing under the Endangered Species Act. Where they go in winter has been a mystery for years. Winter sightings off the West Coast - as far away as San Francisco - increased after scientists called on coastal residents and fishermen to watch for the sleek black and white animals.

It is generally believed that the Puget Sound pods - also known as Southern Residents - based their travels on the availability of fish, particularly salmon. Resident killer whales eat nothing but fish, as opposed to the wide-ranging "transient" orcas, which eat marine mammals.

What K and L pods eat in winter remains largely unknown, although their return in spring usually corresponds to early runs of salmon migrating back to their natal streams. As runs of chinook and sockeye decline up north, the whales move into South Puget Sound, where they dine on coho and chum, observers say.

Those observations are confirmed by early results of recent studies in which researchers in boats pick up bits of fish tissue left on the surface by orcas. The species of fish can be identified with DNA tests or by observing fish scales under a microscope.

"One of the things that has fascinated me is this underlying relationship with the fish," said Brad Hanson, a marine mammal researcher with National Marine Fisheries Service, "They (the orcas) seem to assess the environment and somehow make decisions based on those assessments."

What the orcas are eating may play a critical factor in their long-term survival. The whales, recently listed as endangered, are known to contain extremely high levels of toxic chemicals. Researchers want to know if they are picking up the chemicals from salmon or possibly from other, more-contaminated fish that the orcas may consume when salmon are less available. Chinook salmon, apparently their favorite food, were themselves listed as "threatened" in 1999.

For several years up until 2005, autumn chum returned in large numbers to Puget Sound, which may explain why the orcas stayed around into January, if not February. But this past autumn, the total number of chum was less than
the years before, according to Jay Zischke, a salmon biologist with the Suquamish Tribe. Because of early rains in September, some of the fish also escaped up into the swollen streams. It's not known if that caused the whales to depart for the ocean sooner. But observers say the whales did not travel into South Puget Sound as frequently this fall as in years past - and they did not stay as long.

"We had commercial fishing going through early November," Zischke said, "but the runs did seem to shut down pretty rapidly. Normally, we see fish off the west side of Bainbridge Island until Thanksgiving." Fish were fewer, he said, but salmon bound for the Nisqually River were coming through Puget Sound until well into December. They should have been available for the whales. And so researchers are left to ponder the orcas' travel patterns, reinforcing an old saying among whale observers: When you think you've figured them out, they will do something different.

Source: kitsapsun.com