Whales Ho !
September and October are the peak months when humpback whales (tafola) visit our balmy waters. It's almost impossible not to get excited when one is spotted. Most of us feel inexplicably privileged for a brief glimpse into their mysterious world, and there's an uncontrollable urge to shout 'thar she blows'.
Part of our fascination with whales is their huge size, of course. Adult humpbacks (Megaptera novaeangliae) grow up to 50 feet long and weigh about 40 metric tons (which equals the combined weight of 200 sumo wrestlers). We rarely get a chance to see the whole whale, except when they make a spectacular leap (“breach”) out of the water. We usually see only their air spout or their humped back as they prepare to dive:
Humpbacks are air-breathing mammals (like ourselves) that live their complete lives in the ocean. They reproduce like all land mammals, but they do it underwater. Whales obviously have to make sure that their babies don't drown while being born. Mother whales nurse their young for about a year.
These whales eat small schooling fishes and krill (small shrimps). They feed by sucking in tons of water in a single mouthful, and then strain the food out as they expel the water. The out-going water is filtered through specialized structures called “baleen”, which looks (with a little imagination) like a mouthful of coconut fronds. Humpbacks lack real teeth because they have no need to bite or chew their tiny food items. It seems odd that the whale, which is one of the world's largest animals ever, feeds on such small things.
The
appearance of humpbacks in Samoa is an important segment of their grand
migration up and down the South Pacific Ocean. During the warm months
of the southern hemisphere, our whales feed in the rich waters of Antarctica,
located 3,200 miles to the south of us (see map). Biologists call this
particular group of whales the “Group-5 Antarctic stock”. When Antarctic's
bitter winter sets in, the Group-5 whales seek warmer waters. They migrate
northward, with some going towards Australia and others migrating towards
Tonga. Apparently most of this latter group remains near Tonga, but at
least some migrate onward to Samoa. However, one of our whales was sighted
near Tahiti, so their migration patterns still hold some surprises for
us.
A few humpbacks might arrive in Samoa as early as July or leave here as late as December, but they are most common here in September and October. They occur in small groups of adults or in mother-calf pairs. Humpbacks have been sighted around all 7 of the islands in the Territory, but we don't know how many are actually here. They migrate here to mate and give birth to their young. And, interestingly, they stop feeding while here -- only when they return to the Antarctic do they resume feeding.
 |
| After G. Waller, M. Burchett &
M. Dando. 1996. SeaLife. Smithsonian Inst. Press (Wash. DC). |
While an occasional spout of whale-breath can be seen in our local waters, you can also hear the whales if you stick your head in the water. Humpbacks are famous for their unique “songs”. Yes, whales sing! During mating season, male humpbacks sing to either attract females or to defend their territory from other male whales, much like birds do with their own songs.
The whale's song is haunting and complex. It sounds like a eerie series of chirps, squeaks, whistles and grunts. I know that “grunts” don't seem like they could make much of a song, but you just have to take my word for it. It is unlike anything you have ever heard. Scuba divers can hear the singing if the they hold their breath and pay attention. Snorkelers can also hear the songs, but they have to dive at least 10 feet deep to get below the noisy surface layer of water. The song lasts about 10-20 minutes, it has a beginning, middle and end, and all males of the same stock sing the same song. Biologists can therefore identify where a whale comes from by listening to its song. For example, Hawaiian humpbacks sing a different song (than the Samoan humpbacks), because they belong to a different stock of whales that migrates between Hawaii and Alaska. The whales' song is one of the world's wonders of nature and it's at our doorstep.
Humpback whales are currently listed as an endangered species because their world-wide populations were decimated by whalers in the 1800's and 1900's. By the time commercial whaling was stopped in 1966, 95% of our stock (Group-5) had been killed. Recovery of Group-5 has been unexpectedly slow, probably due to continued whaling by Soviet factory ships as late as 1972 and a subsistence harvest of these whales occurred in Tonga up to 1978. In any event, whales in American Samoa remain few in number, and in some years hardly any are seen here.
Because humpbacks use our waters to give birth to their young, it is important to protect them when they are here. Enjoy their presence, but don't pester them. Avoid the temptation to boat right up to them or follow them at close quarters. Boaters, divers and swimmers should stay at least 100 yards away, and watch from there.
P. Craig, NPS