Humpback Whale Migration Update: April 23, 1997

Center for Coastal Studies

To date, most of the identified whales have been large females, although Ms Jooke Robbins of the Center for Coastal Studies reports that lately they have been seeing groups of unfamiliar whales. These individuals may be transients -- passing through this part of the Gulf of Maine on to other feeding grounds. (See my last report about the five feeding grounds in the North Atlantic.)

The last challenge question was about this grouping of whales by sex and age.

Whale researchers believe that the first group of whales to head north is the group of pregnant females and resting females who have had calves in the previous year. Why would these be first? Perhaps to get to the feeding grounds to start building up blubber reserves and to provide nutrition to the growing fetus. The resting females would be recovering strength from the rigors of birthing and nursing. The second wave of whales is usually juveniles -- those who are not concerned with mating yet (so they wouldn't have to stick around down south) and who are still undergoing fast growth. These whales would be followed by adult males and females who stayed behind in the Caribbean as long as possible in order to mate. The last group to appear in northern waters are the mothers and calves. The babies need to build up their strength (through nursing on their mother's rich milk), plus their swimming speed is undoubtedly slower (although some humpback scientists have reported seeing calves swimming close to their mothers and gaining some hydrodynamic advantages from this association).

An excellent description of humpback whales can be found in "A Field Guide to Whales, Porpoises, and Seals from Cape Cod to Newfoundland" by Steven Katona, Valerie Rough and David Richardson. They note: "Most females give birth every two or three years, but several females have borne calves annually. Pregnancy lasts for 11 to 12 months, and the calf, usually about 13 to 15 feet (3.75-4.5 meters) long at birth, nurses for up to a year and grows about 1.5 feet (45 cm) per month. Protective of her calf, a mother will not abandon it, even in extreme danger. Early whale hunters took advantage of this behavior, first killing a calf, then killing the mother, who refused to leave the carcass."

That's too depressing a statement to close with, so I thought I'd let you know that for my next report I am hoping to have some personal observations from a whale watch (if weather permits). Also, I'll be observing a meeting soon in which whale watch educators from around the world will be developing whale watch naturalist guidelines. At this time, representatives from at least 12 countries, including Finland, Italy, Japan, South Africa and Columbia are planning on attending. I'm hoping to provide some interesting information from around the globe in future reports.

Until May 7th, this is Anne Smrcina from the Stellwagen Bank National Marine Sanctuary signing off.

The Next Humpback Whale Migration Update Will be Posted on May 7, 1997.