Recently I was lucky enough to participate in my daughter’s Marine Biology Class field-trip – a whale watch cruise with Ocean Sports. This adventure took place on a sleek 45-foot catamaran that put out of Anaeho‘omalu Bay. We assembled at the Waikoloa Marriott beach, and shuttled out to the catamaran on a glass-bottom transport boat. Humpbacks like the shallow waters off this north-west side of the Big Island because there are fewer predators here. Sharks tend to hunt in deeper water, where currents bring prey up. At Kailua-Kona, 25 miles south of here, the sea floor drops 10,000 feet just a couple miles off-shore, while here, the water is only 1000 feet deep at the same point. Where there’s nothing to draw sharks, it’s much safer for baby humpbacks.
While settling in, the captain of the Manu Iwa gave us the usual lecture that it’s no disgrace to get seasick, but that it’s best to head to the back of the boat and go for distance. My daughter’s class was joined by a Girl Scout Troop from Kā‘u. I thought the age range might cause a problem for Claire, the on-board biologist. But she handled the transition from 9-year-olds to 17-year-olds with aplomb. She was right up there with the whales as the best thing about the cruise.
Claire started with the usual facts about humpbacks, and in particular, this Central North Pacific population. On average: life span 45 – 60 years, 45 – 60 feet long, weigh 25 – 40 tons, males smaller than females, pectoral fins 15 feet long, migrate at a speed of 15 miles per hour, spend summers in Alaskan waters and winters here to give birth. Adult eyeballs are as big as grapefruits. They are farsighted under water, but nearsighted above water, as when they spy hop to see what’s going on.
But she had an inquisitive audience (okay, it was me) and soon delved into stuff I hadn’t heard before. (See Thar he blows… and Humpback heat run, catamaran style for last year’s adventures with whales.)
Most of us think that the most destructive era for whales was the post-Cook whaling period of the late 1700 – early 1800s. But Claire told us that even more whales were harvested in the 1950s and ‘60s for pet-food and fertilizer (ground whale bones). Soon after, humpbacks became a protected species.
Our first sighting was a mother-calf pair. She said that while the sighting wasn’t unusual, “you are far more likely to see mothers and babies near Maui. Maui is the nursery, while the water near the Big Island is the singles bar.” I’m not sure the 9-year-old Girl Scouts got it, but that’s probably what Claire intended.
She told the kids that humpbacks will “give a better performance” when people shout, hoot and generally make noise. Normally it’s difficult to get kids to shut up. Not this time. I was the only one consistently hooting and letting the whales know we appreciated their presence. My daughter has long since stopped being embarrassed by my behavior.
More cool facts: the mother’s milk is 50% fat and tastes like equal parts of sugar, milk and the oil packed with canned tuna. While baby humpbacks have been seen playing with dolphins, they don’t play with other baby humpbacks. Claire explained it’s because the mother can’t afford to feed the wrong baby. She doesn’t eat all winter and is continually losing weight. Her milk has to go to her baby.
Claire asked how we know that the whales don’t eat while here. I gave the obvious answer – no food. She also pointed out that if they were eating, we would see whale poop. “Believe me, you’d know it if this water contained whale poop.” Their eating and breathing systems are separate, so they never choke on their food or have soda coming out their nose. They also do not drink the sea water, as it would dehydrate them. In summer, they get water from their diet of crustaceans. In winter they get water from the breakdown of fats in their body as they lose weight. Efficient water savers, their bladder holds only five gallons; there’s no need for more.
Claire also told us that the spray that comes out of their blow hole is air entrained in water (like steamy breath in winter) and whale snot. Whale snot? Who knew?
And now, the next exciting topic – whale sex. There are about two times as many male humpbacks in Hawaiian waters as females. They follow the females around in competition pods. Last year I learned this behavior was called a heat run, but apparently, that’s no longer appropriate language. Anyway, if the mother comes back next year to give birth to a new baby, she obviously has to get pregnant this winter. The males are happy to accommodate. Some researchers speculate that a second male may need to assist, but since no one has observed the mating process, no one knows for sure.
We witnessed several types of aggressive male behavior, all designed to scare off other males in the competition pod. (Note that females also exhibit surface behaviors, perhaps to show excitement, size/fitness for mating, and their location.) They waved their pectoral fins in the air. They slapped the water with their tails; one male managed 16 continuous slaps. Imagine thrusting a third of your body weight straight out of the water and bending it to slap hard on the water – talk about belly crunches! Occasionally they will hit other males with their tails or fall on them. They also blow bubbles, but we weren’t close enough to see that.
Claire pointed out that when whales leap and fall back into the water, it is almost always onto their backs. That’s because their ribs are not connected to their sternum, and they could puncture a lung with their own rib. Besides aggression, whales also leap and fall to remove barnacles. At times they inadvertently cut other males with the barnacles.
The folks with Ocean Sports have observed that the breaching / slapping activity seems to increase when the wind picks up and the water gets choppy. Water slapping appears to be a good way to communicate and be heard over the sound of the waves.
Humpback males also sing (listen here), as we heard with the catamaran’s hydrophone. Moms and babies do make noises, but they don’t sing. Claire told us that researchers think the singing keeps males aware of each other so they can keep their distance when not directly tracking a female in heat. While singing, they are “standing” still at a 45̊ angle (head lower than their tail), and pectoral fins out away from the body. Claire said that if a whale stops singing while they are listening on the hydrophones, they know that it will surface soon to breathe.
Whales are mammals. So Claire walked the Girls Scouts through the mammal characteristics: vertebrates, warm blooded, and suckle their young with milk. Most also bear live young. All have hair on their bodies. Check, check, check, check and … hair? Humpback whales have hair that sprouts from fist sized-knobs called tubercles on their head and chin. Cool.
If you get to the Big Island, be sure to see the whales. But plan your trip carefully. They’re only here December through March.
For more essays on whales in Hawaii see:
And for my whale trip in Mexico see:
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