Second juvenile humpback whale in six weeks washes ashore in Fort Bragg

A young humpback whale washed ashore on the northern edge of Fort Bragg on Saturday, the second in six weeks.

Because the 31½-foot male calf was so decomposed, a cause of death may never be determined, though tissue and bone samples have been collected.

The whale’s blubber was thick, suggesting it was well-fed and did not die of starvation. There were no overt signs of ship strike, another frequent cause of coastal whale deaths, said Sarah Grimes of the Noyo Center for Marine Science.

The center is one of the organizations that studies stranded whales under the California Academy of Sciences and the National Oceanic and Atmospheric Administration’s West Coast Stranding Network.

The first whale, a 26½-foot male, was found Sept. 12 south of town, just outside Noyo Bay. That whale also appeared well-fed.

“So two young, two juvenile male humpbacks, not overly thin, not emaciated, and within about a mile and a half of each other within about six weeks of each other,” Grimes said. “And my only thought on that is we’ve seen a lot of humpbacks along the coast since August. We’ve seen a lot of humpbacks up and down the coast feeding.”

Justin Viezbicke, NOAA’s California stranding response coordinator, said the finds did not raise alarms.

“We’re in that time of year when humpbacks are moving around,” he said, noting that humpbacks on the central and north coast are becoming less tied to seasonal migration and more of a year-round phenomenon due to food availability.

Scott Mercer and his wife, Tree, have surveyed whales and other marine mammals along the northern Sonoma and south Mendocino coasts for years under the name Mendonoma Whale and Seal Study.

“In 10 years, we’ve not seen the numbers of humpbacks, especially feeding humpbacks, nor the persistence into autumn that we are observing this year,” Mercer said by email. “In the past, on a typical autumn day, we would find maybe a half-dozen humpbacks foraging along this shore. Last week, even with some bad observation weather, we documented 97 sightings of humpbacks. The phenomenal abundance of anchovies that has brought hundreds of humpbacks into places like Monterey Bay, has spread northward, and brought humpback whales with it.”

Some humpback populations are endangered, so scientists want to be aware of any unnatural losses. Each necropsy can supply valuable information, not only about the well-being and biology of the individual animal, but on the health of the ocean ecosystem, as well.

“Every example is like a textbook’s worth of knowledge,” Grimes said.

Some initially worried that one of the two dead calves might have been from a popular female humpback name Fran, who was tracked and photographed up and down the California coast into Mexico for 17 years before her death from an apparent ship strike in August. Fran, whose carcass washed ashore in Half Moon Bay, was known to have had a calf earlier, though it may have been old enough to wean on its own.

Grimes and her partners with the California Academy of Sciences, Cal Poly Humboldt and the Marine Mammal Center have had two other unusual strandings this year.

A dead beaked whale, a denizen of extremely deep water, washed ashore May 15 at Jug Handle State Natural Reserve, about 5 miles south of Fort Bragg.

Then July 29, another deep-water species, a large sperm whale, turned up in a rocky cove off the Mendocino Headlands and Portuguese Beach.

Sperm whales, long hunted for their oil, are endangered throughout their range and are rare on the coast, as they feed at depths up to 10,000 feet.

Males can reach up to 52 feet in length.

An effort in early August to tow the sperm whale off the reef to a more suitable inspection point failed when the whale sank before it reached the shore.

The Noyo Center and its partners are still hoping to retrieve samples from the whale that might provide data.

Grimes and her team were able to recover pieces of baleen, pelvic bone, skin, whale lice, blubber and other tissue from the recent humpback whale to study.

Grimes said she will continue to monitor the remains if they stay on the beach in the event the skeleton eventually reveals fractures or any other evidence of value.

Marine mammals offer a window into the health of the world’s oceans and changing marine conditions, and are closely monitored under the auspices of the National Oceanic and Atmospheric Administration.

The federal agency has been tracking gray whales, whose population has been in decline since 2015-16 and is estimated to have fallen by 38%, according to a report released earlier this month.

West Coast gray whales also produced the fewest calves on record this year since assessments began in 1994, NOAA reported.

An “unusual mortality event,” or UME, was declared in 2019 amid continued strandings. Many of the gray whales that washed ashore were emaciated, though the evidence was not consistent. Just over 600 stranded gray whales have been found on the coast of Canada, Mexico and the United States since 2019, NOAA said.

Investigation so far suggests one culprit may be diminishing sea ice and shifting ocean conditions in the Arctic, where gray whales feed, redistributing their prey and leading to poor nutrition among animals whose annual migration takes them 10,000 miles around-trip, NOAA reported.

A similar population decline in the late 1980s to the early ‘90s lead to a decrease of about 40%, though the whales later recovered to a higher point than previously, resulting in their removal from the Endangered Species List. The same occurred in 1999 and 2000, when a decline of 25% was followed by a new peak in 2015-16.

You can reach Staff Writer Mary Callahan (she/her) at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.