maybe they don't like the tunes

Whale charmers try to coax humpbacks
by Glen Martin, San Francisco Chronicle Environment Writer
Friday, May 18, 2007

(05-18) 04:00 PDT West Sacramento, Yolo County -- Researchers are sticking to their plan to use humpback whale recordings to entice two wayward and wounded whales from the Port of Sacramento, despite a day of failed attempts on Thursday.

And although worries are increasing that the whales may not have enough to eat, experts say they likely have at least a few more days before trying more stressful ways of moving the mother and her nursing calf.

Biologists and veterinarians are using an underwater broadcasting device called a hydrophone suspended from a U.S. Coast Guard cutter to transmit a variety of humpback sounds that had been collected over the years by recording engineer Bernie Krause.

Peter Folkens, a research associate with the Alaska Whale Foundation, said different types of humpback vocalizations were used in various combinations.

"We have sounds from social, feeding and prey aggregation," or communal efforts by humpbacks to herd fish, Folkens said. "We're trying different things, trying to find something that works. This is new territory for us -- we've never dealt with a pair of whales this far up a freshwater system."

The whales have gained international renown since they were first spotted in the Sacramento-San Joaquin River Delta on Sunday. They have since set an inland travel record for humpbacks, traveling more than 70 miles up the delta and the Sacramento River Deep Water Channel to the outskirts of the capital city.

Both whales were wounded by a ship propeller, either in the open ocean or shortly after entering the bay, Folkens said. The wounds are fresh and relatively superficial, he said, and do not appear to be life-threatening.

Folkens said the injuries are consistent with a single propeller strike from a fairly large ship.

"From the position of the wounds, it appears the mother was nursing the calf, which was suckling while on its side," he said. "It looks like the propeller hit the mother on the back and the calf on the flank."

Researchers hope the whales eventually will respond to one of the recording combinations and follow the cutter back down the shipping channel, through the delta and out the Golden Gate.

Folkens said research indicates humpbacks ignore recordings "about 90 percent of the time, but respond rapidly and dramatically 10 percent of the time. We're looking for the combination that produces that rapid response."

There is a successful precedent for such a strategy. In 1985, recordings were used to lure Humphrey, the last humpback to enter the delta, back to the ocean.

Joe Cordaro, a wildlife biologist with the fisheries branch of the National Oceanic and Atmospheric Administration, said the recordings used during Humphrey's rescue were among the vocalizations played Wednesday.

But the two whales in the shipping channel showed little interest in the underwater concert. As they've been doing for the past three days, they simply milled about the port's turning basin, surfacing regularly to breathe.

U.S. Coast Guard Lt. Amy Marrs said a large freighter and pilings at the port may have interfered with underwater acoustics, confusing the whales.

"The freighter was offloading cement, and we asked them to stop, which they did," Marrs said. "We're doing everything we can to minimize noise, which can interfere with the operation."

Folkens said the strategy for moving the whales will stay the same for the foreseeable future. Researchers also have the option of forming a flotilla of boats behind the whales and banging pipes to drive them toward the sea -- but that would be stressful to the animals, and is not under immediate consideration, Folkens said.

Experience with Humphrey -- who stayed in the delta for 26 days -- indicate scientists have some time to work with the two whales, Folkens said.

"This may take days or weeks," he said. "We have time to work out a plan; there's no need to get desperate. We want to find a combination that works -- we don't want to shock them."

But researchers acknowledge that an extended stay in the shipping channel will also stress the whales. For one thing, the mother will have little or nothing to eat. Humpbacks typically consume huge quantities of small, oil-rich fish such as anchovies, herring and sardines.

In the spring, large numbers of humpbacks typically congregate along the California coast to gorge on vast aggregations of sardines and anchovies. Their intensive feeding replenishes their stores of blubber after wintertime calving and breeding in the warm waters off Mexico, where they typically do not eat.

In contrast to the teeming waters off the Farallones and Monterey Bay, the shipping channel is slim pickings, offering nothing more than a few catfish, carp, and the occasional striped bass and sturgeon -- hardly enough to keep a 45-ton mother nursing a 20-ton calf.

Cordaro said there are signs that the female whale is losing some blubber.

"We're seeing some depressions along the dorsal area, which indicates she has lost some reserves," he said. "The worry is that if she stays up here too long, she may not have enough strength to make it back to the ocean where she can feed."

Cordaro said researchers feel their mission has a fair chance for success, but cautioned against excessive optimism.

"We don't want everyone to get tremendously enthusiastic that it's going to work, and then become devastated if it doesn't," he said. "We're facing some long odds."

It remains unclear why the whales entered San Francisco Bay in the first place, but their apparent compulsion to push northward up the delta and into the shipping channel may be explained by their migratory instincts, Folkens said.

At this time of the year, Folkens said, local humpbacks are moving from Mexico north to their feeding grounds off the California coast.

"One thing we noticed with these two is that they always seemed to be tracking on the north banks (of the bay and delta)," he said. "They probably felt they were heading in the right direction for this time of the year, the direction that would take them to the ocean. They didn't count on the Siskiyous and Mount Shasta getting in their way."

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/05/18/BAGEIPTFEJ1.DTL

This article appeared on page B - 1 of the San Francisco Chronicle
© 2007 Hearst Communications Inc.