A Surprise Encounter with Sei Whales
May 16, 2018
Summer on the Farallones isn’t all about the birds. In addition to daily opportunistic sightings, we conduct standard 1-hour whale watches from atop Lighthouse Hill to document the timing and abundance of Cetaceans around the island. These data are useful in particular for showing where whales are in relation to the shipping lanes leading into San Francisco Bay, to better inform mitigation measures aimed at reducing the number of ship strikes.
On one particular whale watch, during an exceptionally calm day, we came across a feeding flock of 6 black-footed albatross and several dozen pink-footed shearwaters. We considered the possibility that this flock was associated with killer whales, since albatross have been known to scavenge on orca kills, and killer whales had been reported in recent days just south of us in Monterey Bay. Sure enough, after watching for a few minutes a tall black dorsal fin came into view, followed by two smaller fins. A pod of transient killer whales that were feeding on some unknown pinniped at the surface. After radioing the sighting to the rest of the crew, everyone made it up to the lighthouse for a look before they eventually departed to the west.
After the killer whales had left we decided to keep looking around for other sightings. Within minutes a blue whale surfaced right next to the East Landing mooring ball, in water probably half as deep as the length of the animal itself. As if that wasn’t good enough, someone pointed out a small pod of whales swimming toward the island. They were all dark baleen whales with a visible blow, six of them traveling in tight formation towards an islet we call Sugar Loaf. Initially, we assumed perhaps it was a group of minke whales, clumping together in response to a pod of their natural predators nearby. The shape of their rostrums, size, behavior, and blow were all wrong though, and as they got closer we couldn’t see an signs of white patches indicative of minkes on their pec fins. They were too small to be fin or blue whales, too big to be minkes, and definitely not a toothed whale. The only other obvious possibility for this part of the world is the sei whale, a species of rorqual found in temperate waters worldwide, but generally seen much further offshore and rarely sighted off California.
To put this sighting into context, only 17 sei whales have ever been seen on the Farallones since 1987, and generally the sightings consisted of a solitary individual. Not only did this group contain a Farallon record breaking 6 animals, but they swam close enough to the island for us to get excellent looks for a prolonged period of time, and even photos of the event. Truly a rare and amazing sight.
Photos/Figure/Text by Mike Johns