The Search Area

by Jessica Miller

July 19, 2006

The following posting is from Carroll, who is onboard in the Bering Sea…

This afternoon we entered the southern part of our search zone for humpback whales, in the area northwest of St. Matthew and southwest of St. Lawrence. It’s less than 200 miles between the two islands, but our search will take us back and forth across 700 miles of sea.

It seems like a long way, but it pales in comparison to what the humpbacks themselves do every year. The humpback whale has the longest migration of any mammal, making a ten-thousand mile roundtrip between its calving grounds in temperate seas and its feeding grounds closer to the poles. Even though the humpback is the most studied large whale on earth, our understanding of which humpbacks go where in their annual journeys is still incomplete.

Humpbacks have three major winter calving grounds in the North Pacific—off the coasts of Mexico and Central America; around Hawaii; and in the western Pacific from south of Japan to the Philippines. Scientists have also identified the major summer feeding grounds—off the U.S. Pacific coast from California to Washington; from northern British Columbia across the Gulf of Alaska; and in the Aleutian Archipelago and Bering Sea. But the connections between these areas are still being worked out. Most humpbacks from Mexico and Central America winter off California, Oregon and Washington. But there is a smaller, and seemingly distinct group, that heads farther north to British Columbia and the Gulf of Alaska. Some Hawaiian humpbacks also summer in the Gulf of Alaska. Still others, however, have been spotted in the Aleutians and southern Bering Sea. And what of the humpbacks from Japan? No one knows for sure yet, but one hypothesis is that at least some of these whales travel north into rich waters of the central Bering. It’s an open question, that hopefully this trip will help answer.

In 1999, a whale survey of the region identified significant numbers of humpbacks in the waters southwest of St. Lawrence, near the Russian border. The same waters we’re sailing through now. With any luck, we’ll encounter some of those humpbacks and get close enough to take the photo identification shots necessary to match the whales here to individuals already documented further south.

It won’t be easy. The 1999 survey had 10 humpback sightings in more than 6,000 miles of effort. Nearly ten times the distance we’ll be covering. But finding even one match will help us better understand the movements, and the habitat needs of this remarkable migrant and open an unexplored new feeding ground to humpback research.

It’s worth a few hundred miles at sea.


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