September 26, 2017

A Dall-lightful day in the Salish Sea

Dall's porpoise in the Salish Sea

09/25/17 – M/V Sea Lion – 12 PM

Just as the rain showers tapered off to a faint drizzle, M/V Sea Lion made her way out of Friday Harbor Marina south towards Salmon Bank off San Juan Island. Moving though San Juan Channel, little 5-6 foot harbor porpoises broke the glass-like surface before disappearing back into the water. We began our search for whales in the confluence of the Strait of Juan de Fuca and Rosarios Strait. Suddenly, tiny rolling black and white bodies appeared ahead of us. A pod of Dall’s porpoise! They were visible in all directions, making small little waves as they surfaced about. These robust little cuties can get up to 7 to 8 feet long and feed on schooling baitfish with their spade-shaped teeth. This unique tooth shape helps with grasping their prey and also makes them different than their dolphin cousins who have cone-like conical teeth.

Continuing on, we made our way over to Hein Bank before turning back towards San Juan Island in the direction of a few bait balls. Bait balls can be observed at the surface of the water because the large groupings of birds that take advantage of the schooling fish being pushed up by a predator underneath. As we slowly moved between small clusters of sea birds, someone shouted “WHALE!”. There it was, a 30-foot minke whale off our port side. Despite its zig-zag dive pattern, we were able to get some amazing looks as this solo whale lifted its head out of the water several times. It was also taking two breaths before going down for another 5 or so minute dive, allowing us to predict its behavior. With the cliffs of American Camp north of us, we were able to watch this feeding baleen whale for about 30 minutes before it was time to head back to port.

Odontocetes like the Dall’s porpoise and mysticetes like the minke whale have different feeding mechanisms. Odontocetes have teeth like you and I to catch their prey, while mysticetes have a structure hanging only from their upper jaw called baleen that is used like a filtering system. Baleen is made from the same protein as your hair and your fingernails, keratin. The hair-like structure traps small bait fish or plankton while the whale expels the salt water from its mouth before swallowing a mouth full of goodies. We were able to see our minke whale friend lunge feed once during our trip today, absolutely amazing!

After a beautiful day on the water with two very different species of cetaceans, we made our way back into Friday Harbor just as the sun broke through the grey clouds.

-Naturalist Courtney