Subject: Humpback whale question

Patrick Miller (omalley@cetacea.whoi.edu)
Wed, 15 Jan 1997 16:11:31 -0500

> 
> Patrick,
> 
> I'm doing a research project on Humpback Whales. I've been able to locate
> most of the information by surfing the net. Could you provide some
> assistance in the following two areas:
>       1. Survival rate of Humpback calves
>       2. Current population of Humpbacks
> 
> Thank you,
> Sean McQuilken


Dear Sean,

Your questions are interesting ones. Humpbacks are distributed in all
the oceans of the world. Prior to commercial whaling, there may have
been as many as 100,000 humpback whales, or even more. In many areas,
population sizes are unknown, or only roughly estimated, so the exact
number of humpbacks world-wide isn't known. However, a ballpark
estimate would be around 9,500 whales (assumming approximately 5500
in the North Atlantic, 1,500 in the North Pacific, and 2,500 in the
southern oceans).

Even less is known about the survival rate of humpback calves. Females
only produce one calf every 2 years or so, although sometimes calves
are born in consecutive years. As it is difficult to monitor the
number of births and keep track of individuals in subsequent years,
survival rates are difficult to obtain. Changes in pigmentation
patterns (ie. changes in intensity and/ or color patterns) with age
make it difficult to recognize calves in subsequent years. Some
researchers have suggested that the survival of calves born in
consecutive years might be lower than those born after larger
intervals due to energy demands on the mother, but it isn't known for
sure, and in several cases calves born in consecutive years have
survived just fine. Researchers are trying to answer this question of
calf survival rate as we speak.


				yours in whale research,


					Patrick