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Wednesday, October 22, 2014         

OCEAN WATCH


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The humpback of island fame has 23 cetacean cousins here

By Susan Scott

POSTED:


One of the reasons I leave my sailboat, Honu, in Mexico's Sea of Cortez (Gulf of California) is that the marine mammals there are not only abundant, but they also show up at the boat. I've had a sperm whale dive under my hull, and a fin whale swim so close I could smell its stinky breath, and several times dolphins surrounded the boat in such numbers I couldn't see the end of them.

Just before I left home, though (I'll be sailing in Mexico when you read this), I wished Honu were back in Hawaii.

The reason for this was a report I received of a recent five-day whale and dolphin research cruise off Kauai. After reading the details and looking at the amazing photos, I thought I must have misread the dates of this expedition. Could these people really have seen all this in five days? Yes. I read right.

The team, led by whale specialist Robin Baird of Cascadia Research in Olympia, Wash., has been studying (among other things) Hawaii's cetaceans, the scientific name for all whales and dolphins, since 2000.

Most of us think of whales as large and dolphins as small, but size doesn't matter. Researchers classify cetaceans according to teeth: those with and those without.

Eighteen species of toothed whales, which include dolphins, and six baleen whales, which include humpbacks, have been documented in Hawaii's waters. Of these 24 cetaceans, the Cascadia team has seen them all in the past 10 years.

They didn't see them all during their trip around Kauai from Feb. 16 to 20, but those they did see were remarkable.

Humpback whales were a given because this is the height of their season in Hawaii. But humpback whales have been well studied here, and Cascadia's focus is on species not well studied. Among those are rough-toothed dolphins, spotted seven times in three days, the first while the vessel was still anchored in Hana-lei Bay.

Rough-toothed dolphins are the fifth most common species of toothed cetaceans seen in Cascadia's long-term study and represent about 10 percent of all sightings.

The rough-toothed dolphin is named for fine vertical lines on its teeth. No one, of course, can look at a living, wild dolphin's teeth for identification, but no one has to. Rough-toothed dolphins look different from our more common bottlenose and spinner dolphins, having distinct beaks, fins and belly freckles.

During one sighting, researchers saw a piece of fishnet covering the dorsal fin of one rough-toothed dolphin and worried that the animal was entangled.

But while the scientists watched, the dolphin dropped the net, and a pod partner picked it up, also on its dorsal fin. Apparently, the dolphins were playing with the net.

Among other cetaceans the researchers spotted, satellite-tagged, photographed and biopsied for genetic studies on their short trip, were short-finned pilot whales, bottlenose dolphins and leaping spinner dolphins with remoras stuck to their skin.

You can check out great photos and more details of this trip at www.cascadiaresearch.org/hawaii/february2011.htm.

Hawaii anglers and sailors can help the Cascadia team with this much-needed, long-term study by sending photos of dolphins and whales around the islands (besides humpbacks and spinner dolphins) to Robin Baird at www.cascadiaresearch.org.

When I sail Honu home someday, I'll go looking for some of the 24 cetaceans gracing Hawaiian waters. In the meantime I'll be enjoying the 33 in the Sea of Cortez.

------

Susan Scott can be reached at www.susanscott.net.






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