Monday, September 26, 2011

Marine Mammals in SE Alaska & British Columbia

Just about the biggest highlight of the Alaska cruise was the chance to see so many varieties of marine mammals.

The biggest, and the most exciting to watch, were the humpback whales. They are very social creatures, and one of their unique cooperative efforts is called "bubble-net feeding." A pod of whales will locate a school of herring, and swim in circles around the school, making the herring condense into a tighter mass. All the time, the whales are singing a low-pitched song, which also frightens the herring so they huddle together. The senior member of the pod then dives below the school, and swims in a circle, blowing a curtain of bubbles that make a cylinder around the herring. The whole pod dives below the cylinder, and the song changes to a high-pitched loud call, which is the signal to lunge upward, scooping up hundreds of herring (and a lot of water) in the whale's pleated, expandable throat. Humpback whales have no teeth, just baleen to filter their food out of the water they gulp in.

The three pods we watched one afternoon and evening performed this feeding routine at least 15 or 20 times, in a big circle around the ship. (Herring are small fish, maybe 6 - 8 inches long; it takes *hundreds* to make a whale mouthful, much less a belly full.) We were able to hear the songs and see the bubble net clearly. So could the gulls and other seabirds, who appeared from nowhere every time, to hover over the bubble net in anticipation of picking off any leftover herring.

We watched until it was too dark to see, but we could still hear the song into the night.

Here's a long shot in which you can see whales' mouths gaping inside a ring of bubbles (click to enlarge):

At one point, one of the pods made their bubble net right up next to the ship. Lots of passengers (including me) were so gobsmacked seeing these giants leap up out of the water, mouth first, that we didn't get our camers to our faces quickly enough. All I got was a shot of the last barnacle-covered nose sinking back under the water. You can see from the arm of the passenger next to me just how close the whales were to the ship. It was truly an OMG moment:

DH had retained his composure enough to get this incredible shot showing the pleated throat that expands to gulp in a huge volume of water along with as many herring as possible. There are portions of at least 4 whales in this shot, mostly upside-down in the water:

After this episode, the chief engineer called up from the engine room to ask what the heck was going on - he had heard and felt the thump of fins and tails banging into the ship, and barnacled sides scraping against the hull plating.

We also saw several pods of Orca, and at various times, a pod of Dall's Porpoises, and huge numbers of Pacific White-Sided Dolphins. The porpoises (maybe 25-30 of them) happily rode the bow wave for almost 30 minutes before dashing off somewhere else.

A few days later, the dolphins (a huge pod over 300 strong) stayed near the ship longer. Some rode the bow waves, but most just kept pace with the ship. A few individuals out on the leading edge of the pod were competing to see who could do the most acrobatic moves - barrel rolls, somersaults, back flips. We all laughlingly agreed it was probably the adolescent males...

The sound made by that number of dolphins was incredible. First of all, these guys were swimming pretty fast, and that many tails thrashing the upper few feet of the water was noisy, like a giant egg-beater. And the leap/exhale/inhale/dive action added another aural dimension. Then there were the huge belly-flop splashes of dolphins hitting the water after a major acrobatic move.

I'll look through DH's photos to see if I can find any close-up dolphin pictures. With my little Point & Shoot camera, I couldn't zoom far enough to get close, but DH was using the DSLR with a long lens. Here's a look at a very small portion of the pod. For every dolphin you see on the surface, there are 3 or 4 just under the surface, swimming like mad and waiting to take their next breath. Again, click to enlarge the image.


neki desu said...

just plian great! the last photo is like those etruscan murals in tarquinia and cerveteri.

neki desu said...

oops meant plain