Whales assumed to have returned to ocean

Published: May 31, 2007 | 6309th good news item since 2003

After more than two weeks of swimming up and down the Delta, a humpback whale and her calf appear to have returned quietly to the Pacific Ocean.

Marine experts are optimistic that the long, worrisome sojourn of the two humpback whales, dubbed Delta and Dawn, is finally over. The two whales that swam their way

90 miles to Sacramento were last seen around 8:40 p.m. Tuesday near Tiburon, a five-mile home stretch from the Golden Gate Bridge. They have not been spotted since.

“We would love to have seen them one last time to say good-bye, but if they made it home, that’s what counts,” said Bernadette Fees of the state Department of Fish and Game at a Wednesday morning press conference.

Rescue efforts came to a close Wednesday evening after authorities in boats and helicopters spent all day searching the San Francisco Bay and beyond the Golden Gate Bridge but turned up no sign of the pair.

Word of an early morning sighting of two whales off Baker Beach gave authorities brief hope in that the pair had indeed made it to the Pacific, but scientists later confirmed the spotting was of a pair of gray whales, said Fees.

By mid-day, rescuers had moved their command center to the Farallones National Marine Sanctuary at San Francisco’s Presidio to be closer to the Golden Gate Bridge in case the whales resurfaced nearby. At the rate they had been traveling for the past two days, U.S Coast Guard officials had guessed that the whales would have reached the bridge around noon.

With no confirmed sighting of the celebrated mother whale and her calf since Tuesday night, authorities wound down their last day of rescue efforts on the assumption that the pair had safely and stealthily swam their way out to sea.

“We’re confident that these animals have swam out to their habitat under the cover of darkness,” said Scott Hill of the National Oceanic and Atmospheric Administration on Wednesday evening.

The whales’ quiet leave-taking came on the tail of a surprising burst of breakneck swimming, following weeks of lollygagging in the Delta.

Experts began to worry that the two were struggling to find their way down the tributary and out to sea. For days they appeared to retrace their course back and forth under the Rio Vista Bridge, prompting rescuers to try a multitude of things to coax them downstream to the Bay.

It was at this point they became seriously concerned about the whales’ health, particularly the condition of their skins. They administered antibiotics on Saturday, the first time that had been done with humpback whales in the wild. By Monday, they saw improvements in skin tone, possibly from the antibiotics, the salt water or both.

Experts also took samples of the whales’ skin to try to learn which migration group they came from and more about their general health.

They hope to eventually track the whales by their dorsal markings, as they did with Humphrey, another humpback who swam into the Delta in 1985 and returned to Candlestick Point in 1990.

Experts are still considering theories about why the two swam into the Delta.

Based on what authorities and scientists have been able to observe so far with Delta and Dawn, Fees said the whales seemed to slow down in the afternoons. But officials do not know what they do at night because they have not been monitoring them after dark.

“If we learned anything about these two,” Fees said, “they are gonna do what they want to do when they want to do it.”

While many officials had wished for the chance for a proper send-off for the pair, they agreed that the rescue experience gave them an unprecedented chance to learn more about the species. It’s the first time marine mammal experts have had the opportunity to monitor the endangered whales for such a long time, Fees said, noting they have learned a lot about their general health. And despite the fact that the bulk of the whales’ progress was made independently, Fees said humans’ use of fire hose spray and the metal pipes were effective at least in deterring the whales from entering hazardous Delta tributaries.

“We saw that we had some influence but didn’t have control,” said Dr. John Calambokidis, a researcher for the Cascadia Research Collective, at a Wednesday afternoon news conference with NOAA officials and others from the Marine Mammal Center in Sausalito. They and others had tracked the daily activities of the whales.

Furthermore, the orchestrated efforts of the many agencies involved worked nearly flawlessly and may become a prototype for the next whale rescue.

“They’ve worked together as a team and they put their heart and soul into it,” Fees said.

Because of the high volume of people seeking information, authorities will continue to keep the Farallones information center open for a few more days.

Published in Animals
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