Keywords: Species and food webs, Mammals, Salish Sea, Salish Sea Currents magazine

A resident population of minke whales is catching the attention of scientists who want to learn if the elusive mammals are found here year-round. While small compared to their cousins the blue whales, minkes are still among the largest creatures in the Salish Sea.

One morning a few years ago, I was out in the San Juan islands in a small boat with Brad Hanson, a biologist with NOAA. Hanson was in search of the southern resident killer whales, which he has studied for many years.  It was a good day for whales, with the sky overcast and the water flat calm. “Perfect conditions to find whatever is out there,” Hanson said as we sped off from Friday Harbor.

The problem was that nothing was out there. Oh, the southern residents were in the area, or so Hanson had heard via the network of casual observers that keeps vigil over this part of the Salish Sea. But none of the pods were where he was expecting them to be. Back and forth we went, first to this cove, next to that bank, all the while scanning the orca-less waters of the Strait of Juan de Fuca. As the morning stretched on, Hanson grew more and more stoic. “It’s something you have to get used to when you work with whales,” he said.   Suddenly, maybe a couple of hundred yards to our starboard, we heard an explosive, telltale pfwuh! We both whirled to see a diaphanous plume of whale breath dissipating into the morning air. The breather was at that moment submerging, its dark sleek back curved, a short but sharp fin cutting a chevron through the water. We waited a moment and then it surfaced, breathed again. A single whale. It wasn’t an orca, that much I could tell. The thought that flashed through my head was baby blue whale.

“What is it?” I asked. “That’s a minke,” Hanson said. “A minke!” I goggled at him. “Is it lost?” “No,” Hanson chuckled. “There’s actually a small resident population in the Sound.” “No kidding.” “Yep,” Hanson nodded. “But no one knows too much about them.” We watched the minke for a bit as it surfaced a couple of more times, but then Hanson decided to motor on. This was not the whale we were looking for. But minkes rarely are in these parts.

Minke whale

A minke whale spotted in San Juan County, Washington, June 2018. Photo Jeff Stacey (CC BY-NC)  

Solitary and hidden

The Salish Sea’s cast of cetaceans doesn’t lack for vivid characters, even as their stage is relatively small. The southern resident killer whales usually get top billing, but there are also the gray whales that either migrate past or stick around as Sounders, a growing population of harbor porpoises that pop up to puff for ferry-goers or other boaters, and others that drop by from time to time.

Among these, minke whales swim for the most part by themselves and out of sight. In appearance they are a study in grays, the dark of their back fading to light on their belly, sometimes with whorls near their pectoral fins, which have bright white swatches across them. Officially called the northern minke whale — a companion species, the Antarctic minke whale, lives in the southern hemisphere — the species is the smallest of the rorquals, or baleen whales. Adults might grow to be “only” 35 feet long and weigh a mere 20,000 pounds. Small though they may be, minkes are widespread, occurring from the poles to the tropics throughout the northern hemisphere, and everywhere from bays and estuaries like Puget Sound out to the open ocean.

Minke whale under water.

Minke whale under water. Photo: Len2040 (CC BY-ND 2.0)

The northern minke’s scientific name is Balaenoptera acutorostrata, and scientists recognize two subspecies, although there are likely three. Here in the northeast Pacific and its associated inland waters, the subspecies people are most likely to encounter is B. a. scammoni, named after Charles Melville Scammon. Scammon was a whaler perhaps best known as the first to hunt gray whales in San Ignacio Lagoon and Ojo de Liebre Lagoon, their calving grounds in Baja California. But he whaled widely along the North American coast and had a hunter’s interest in natural history.

In 1874, Scammon published The Marine Mammals of the Northwestern Coast of North America. (Like Moby Dick, it was a financial failure at first, but has since become something of a classic.) The minke figures in the book, although not prominently, and under an alias; Scammon called it “the sharp-headed finner whale,” noting that whalers also called them “young Finback” or “Finback’s calf.” Not much was known about their habits. “…[T]here is a mystery about its history which we had not been able to solve in the course of twelve years’ observations, during which time we had traced it from the coast of Mexico to the Behring Sea (sic),” he wrote. There was one place, however, where the sharp-headed finner whale could be watched more intimately. “In the Strait of Juan de Fuca,” he wrote, “opportunities were afforded for observing its habits more closely than elsewhere.”

Even afforded those opportunities, Scammon in general seemed unsure what else to make of the minke. The chapter he devoted to it, at barely three pages, is the shortest of those on whales. But as a whaler, harvest likely directed the lens of Scammon’s natural history; and no one, he noted, hunted minkes with any real intent, not even the famous Makahs of Cape Flattery, with their great whaling canoes. (Minkes are controversially hunted elsewhere.)

One hundred and forty-five years after Scammon’s book was published, later little would seem to have changed where minkes are concerned in general. “The seasonal distribution and migration patterns of nearly all populations of minke whales,” wrote the authors of a review on all that was known about them in 2019, “are poorly understood.”

Attention grows

It was not until 1980 that the Salish Sea minkes began to receive more focused scientific attention. That was when Eleanor Dorsey, a scientist working out of The Whale Museum on San Juan Island, decided to start studying them. Dorsey had done research on several species of baleen whales, having been a student of the famed biologist Roger Payne. Taking her cue from researchers who were just starting to sketch the complicated family relationships of the southern resident killer whales, she boated around and photographed minkes whenever she came across them. It was the first time anyone had used photo ID with a baleen whale.

Minke whales

(Upper) Minke whale "Nick Jagger" is identifiable by the nick in the lower trailing edge of the dorsal fin. First encountered in 1981, then again in 2005, 2010-2015 and 2017. (Lower) "Chrissy Hein Bank" is identifiable via white scars on the leading edge of the dorsal fin and nicks on the leading and trailing edge of the dorsal fin. Encountered 2004 -2010, 2013, 2016-2020. Photos: Northeast Pacific Minke Project; Erin Gless

Dorsey was joined that first summer by Jon Stern, a volunteer who had just finished his undergraduate degree in California. Together with another volunteer, Rus Hoelzel, they spent hours on the water, taking pictures of dark gray minke backs. Although the minkes were not as straightforward to identify as the southern residents, which have more obvious markings and colorations, Dorsey found that if she got close enough and the photos were reasonably sharp, she, Stern, and Hoelzel could tell the individuals apart by the shapes of their dorsal fins, or other subtle features. Some individuals the team got to know well, with Stern naming them after aging rock stars or actors. One male first seen in 1981, called Nick Jagger, had a notch on his dorsal fin. Al Pacino had clearly been raked by a killer whale’s teeth at some point in his life. Another with a host of scars was Johnny Rotten, until she showed up with a calf and became Chrissy Heinz. (Minkes are impossible to sex in the field, but most in the Salish Sea are females or females and calves, judging by the few regional stranding records.)

After a few years, Dorsey and then Stern had around thirty-five individuals in their minke catalog, twenty or so of which they might see in a given year. For while the minke is the most abundant of the baleen whales — biologists estimate there may be around half a million in the world—the number of minkes in the northeast Pacific is quite low. Stock assessments for the California, Oregon, and Washington coasts put the overall population in this part of the California Current at fewer than six hundred. But those minkes that Dorsey and Stern saw again and again in the Salish Sea, uncommon though they might be, constituted a resident spring and summer population. They would start to show up near the end of April or early in May and stay as late as November. After that? Perhaps they left for the open ocean, or a different part of the coast. Or perhaps some didn’t leave at all but continued to lurk. No one could say for sure.

The Minke Project

After Dorsey left the San Juans in 1988 to return to Massachusetts, where she was from, Stern and Hoelzel continued the minke project. Stern had also taken Dorsey’s protocols down to California in 1984, starting a kind of companion project around the Bay Area; he eventually became a professor at San Francisco State University, having earned his PhD from Texas A&M University.

As a researcher, Stern was focused primarily on minke feeding behaviors. Like other rorquals, minkes feed by lunging through the water and taking in tremendous quantities of it in their expanded throats. They then push the gallons out with their tongues, filtering the goodies with the strips of baleen that line their upper jaw—zooplankton, crustaceans, schools of forage fish such as sand lance or northern anchovy. But where were they going to find those sustaining hordes of zooplankton and forage fish? By following individual minkes for hours as they swam around Puget Sound, Stern was able to describe their foraging patterns, and the particular ways they optimized the number of potential food patches they could find and visit in a single day.

As the only person studying minkes in any depth in both Washington and California, Stern would become not just the leading expert on the species, but also a kind of clearing house for minke photos or stray information and anecdotes. The species might show up in quirky ways. Volunteers doing coastal surveys for gray whales in California, for instance, would call Stern to say that had seen hundreds or even thousands of minkes passing their stations in just a few days — which, Stern knew, was really probably just a one or two individual minkes going back and forth, back and forth, looking for goodies in the lines of kelp close to the shore.

Two men in a motor boat

Rus Hoelzel and Jon Stern taking photos of minke whales in the 1980s. Photo: Northeast Pacific Minke Project

Although he was professionally based in California, Stern continued to come up to the San Juans for a few weeks every summer, going out on his boat and photographing the resident minkes to see whether new ones were joining the population, until he died in 2017 at the age of 62. “Minkes were really his love,” one of his colleagues would say. “And he was their champion.”

With the passing of Stern, the mantle of the minkes has passed to a researcher named Frances Robertson. (“I guess I am now the Minke Project,” she said when I reached her on the phone in the summer of 2021. “That’s kind of a weird thing to say,” she confessed.) She started working with Stern in 2005 — “fell into it really”—after she had come to the Pacific Northwest from Scotland to study the southern residents. She heard about Stern’s work and was eager to collaborate. She now balances her minke work — “my passion project”—with her job as the Marine Program Coordinator for San Juan County. Her main tasks are to find the time to sort through a large backlog of minke photos and finish some manuscripts that Stern had started over the years. “Jon was a brilliant scientist,” she says, “but sometimes brilliance doesn’t publish.”

More than that, though, Robertson is eager to get back into the field. “It’s been a few years since we’ve had any real field component,” she says. But she recently bought a boat — or half a boat, since it still needs an engine—and her goal is to get out on the water throughout the year when circumstances permit. “One nice thing about minkes is they’re fair-weather whales,” she says. “I want to go out in the winter, see if they’re still here. Obviously, there’s still so much left to learn about them.”

Minke whale swimming in the distance.

Minke whale sighting off Cypress Island, Washington, May, 2021. Photo: estehr (CC BY-NC)

'They are out there'

Hanson never did find the southern residents that day, even though he searched for hours. When we finally pulled back into the dock at Friday Harbor in the late afternoon, he seemed a little glum. “Some days you have the luck and some days you don’t,” he said when he dropped me off at the ferry terminal.  

Even though I knew I was not at fault, I felt apologetic somehow. “Sorry we didn’t see anything today,” I said.

“Hey, we saw the minke,” Hanson said, shrugging. “That’s not nothing.”

True. In the years since that trip, I sometimes think back to that lone minke whale, which I saw for perhaps a minute or so. I have been out on many boats in the Salish Sea in the intervening years, but I have yet to see another minke — at least, not that I know of. But it is nice to know that they are out there.

About the author: Eric Wagner writes about science and the environment from his home in Seattle, where he lives with his wife and daughter. His writing has appeared in Smithsonian, Orion, The Atlantic and High Country News, among other places. He is the author of "Penguins in the Desert" and co-author of "Once and Future River: Reclaiming the Duwamish." His most recent book is "After the Blast: The Ecological recovery of Mount St. Helens," published in 2020 by University of Washington Press. He holds a PhD in Biology from the University of Washington.

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