Garbo of the Oceans: the Mike Whale
By Mary Jane Schramm
The sea was calm off Duxbury Reef, its surface broken only by a few seabirds riding the gentle swell. Nearby, a fisherman bent over a trap alive with Dungeness crabs when suddenly, silently, a dolphin-like dorsal fin broke the surface. Simultaneously, he heard the quiet exhalation of a breath, and glimpsed a bit of black back. The low, inconspicuous blow hung in the cool air as the creature slid silently back into the swell, leaving only silvery chevrons in its wake. No breaching, no tail-fluking; none of the antics that local humpback whales so often displayed. The crabber smiled and resumed work, wondering “What the heck was that?!” This would be considered a good sighting of a northern, or common, minke whale.
BITSY BEHEMOTH: The minke (pronounced “mink-ee”) is the smallest of the baleen whales: those that gulp and filter their food through sieve-like baleen plates, vs. using teeth. Although modeled along the lines of giant blue whales nearly three times their size, minkes reach only 35 feet. Their bodies are grayish-black, countershading to white on the underside. They sport flashy bright-white “cuffs” on their longish pectoral fins, perhaps to help herd their prey. Their diverse diet includes krill, schooling fish, and larger fish. (See fish fly at https://www.facebook.com/watch/?v=10155163635006572).
Minkes are globally cosmopolitan, but generally favor cooler latitudes over continental shelves. Their tapering “needlenose” head reflects their scientific name, Balaenoptera acutorostrata, meaning “sharp-snouted winged whale.” The snout, or rostrum, is flattened, with a single center ridge and double blowholes above. A second species, the Antarctic minke, and several subspecies, grace our Blue Planet.
GARBO-ESQUE: Svelte and sleekly sculpted, they are a study in cetacean elegance. Minkes in this region are usually encountered in nearshore waters as solitary individuals. They’re so mysteriously elusive, they’re considered the “Greta Garbos” among whales.
STRATEGIST: Noted Bay Area whale researcher Jon Stern studied minkes’ spatio-temporal movement patterns off North-Central California and in the Pacific Northwest, and found they used surprisingly sophisticated foraging patterns to locate food. Stern examined their search strategies, identifying Lévy flights or “walks” to optimize their effectiveness in locating prey patches. He also noted their small proportion of body fat stores, and suggested that while feeding, “the diminutive minke plays by a different set of energetics rules” when compared to large, highly migratory whales. This type of information is essential to conservation efforts, as changing ocean conditions can cause disruption of normal prey patterns. Adaptability in foraging strategies is increasingly essential to upper-level predators’ survival.
ECO-ENCLAVE: Minkes in our region appear behaviorally distinct from more northern migratory whales, forming discrete resident groups within specific home ranges. According to the National Oceanic and Atmospheric Administration, the Northeast Pacific "resident" minkes off California, Oregon and Washington comprise a separate stock that numbers around 636 whales, but possibly as few as 369: their secretive habits make them challenging study subjects.
FROM DEATH TO NEW LIFE: In 2019, NOAA’s Greater Farallones and Monterey Bay national marine sanctuaries partnered with Ocean Exploration Trust and others aboard the E/V Nautilus to explore the region’s deep waters. In the Monterey sanctuary they discovered a “whale fall:” a carcass that had sunk to the sea floor, becoming a lavish banquet for scavenging sea life such as octopuses, fish and invertebrates. It was recently identified as a young minke whale. Revisiting it in October 2020 provided scientists with insights into the spontaneous, opportunistic evolution of deep sea communities over the course of a year.
SURVIVAL: Threats include ocean noise and other habitat disturbance, pollution, vessel strikes, domoic acid poisoning, and fishing gear entanglement. Minkes remain the primary target of whaling nations.
NOAA’s Greater Farallones National Marine Sanctuary extends into Drakes Bay in the Pt. Reyes National Seashore, where these enigmatic whales may be sighted. A minke skeleton hangs in the Drake’s Bay Visitor Center, and is well worth checking out.
Learn more about minke whales at https://www.fisheries.noaa.gov/species/minke-whale and about our sanctuary at https://farallones.noaa.gov/ View fascinating footage of the whale fall at the Nautilus Live website: https://www.youtube.com/watch?v=fFtcK1cK1ro
