Ocean Watch

By Susan Scott

Monday, December 15, 1997



It’s unlikely shark killed
whale at North Shore

Last week, a 20-foot-long juvenile sperm whale washed up dead at a beach park on the North Shore.

Biologists said they didn't know the cause of death, but that didn't stop people from speculating. One observer said, "I think a shark did it, because you have plenty of sharks out there."

Good guess but probably wrong. Sharks aren't that stupid. Because to mess with a healthy sperm whale, even a young one, is asking for big trouble.

Sperm whales are the largest of all toothed whales. Males grow up to 60 feet long and weigh up to 58 tons. Female sperm whales are smaller, growing to "only" 37 feet long.

Although they are big and have a mouth full of enormous teeth, sperm whales also find safety in numbers. These are sociable animals, usually traveling in groups of up to 50. During peak breeding season, from late winter to late summer, sperm whales can gather in groups of up to 150 whales.

Such groups consist either of bachelor bulls, or of females and their young accompanied by one or more large males. When not traveling with their harems, these large males roam the world's oceans alone.

And roam they do. Sperm whales cover a tremendous area, traveling from the tropics all the way to the ice packs of both Northern and Southern hemispheres.

They can also be found at a wide range of depths, from the surface, where the spray from their blow hole is distinctively angled, to 10,000 feet down.

What are sperm whales doing at those cold, dark depths? Eating giant squid and octopuses. These whales sometimes bear round sucker marks on their skin from their battles with the big cephalopods. A 36-foot long squid was once found in a sperm whale's stomach.

Although squid and octopuses are sperm whales' main food, an amazing variety of other things have been found in their stomachs: seals, lobsters, sponges, crabs, jellyfish, rocks, sand, glass fishing floats, coconuts, wood, apples, fishing line, shoes, and of course, the ubiquitous scourge of the ocean, plastic bags.

Researchers also recovered a 10-foot blue shark from the stomach of a large male.

And that's why it isn't likely sharks caused the death of the young Oahu sperm whale. Any whale that can swallow a 36-foot giant squid or a 10-foot shark isn't likely to fall prey, or let its offspring fall prey, to a shark, even a big one.

Sure, the carcass of this 20-foot-long whale had several shark bites on it, and sharks were spotted in the vicinity. But that's normal for any carcass drifting in the ocean. Sharks are part of nature's recycling system.

Even though sharks may not be much of a threat to sperm whales, the whales do have two formidable enemies: killer whales and people.

Since killer whales can eat just about anything they come across, they occasionally attack and kill a sperm whale.

People once attacked and killed sperm whales relentlessly, but sperm whales didn't usually go down without a fight. This is, after all, the legendary species that sent sailors flying through the air, smashed their whaleboats and killed Captain Ahab.

Commercial hunting of sperm whales began in 1712 when people discovered that the material in the whales' heads made good lamp oil. The most intense hunting came during the Yankee whaling era of the 1800s and the factory ship whaling of this century.

The good news is that although certain populations have been depleted, the sperm whale today is the most abundant of all the great whales.

Sperm whales are spotted occasionally around the main islands but are more common in the waters of Hawaii's northwest chain.

Ancient Hawaiians carved pendants from the teeth of whales that washed ashore but did not hunt sperm whales.



Marine science writer Susan Scott's Ocean Watch column
appears Mondays in the Star-Bulletin. Contact her at honu@aloha.net.




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