Fresh water whales?

From: Erich Hoyt (e.hoyt@virginnet.co.uk)
Date: Thu Apr 05 2001 - 00:38:33 EDT


>From: Belinda Lowe-Schmahl <bels@flashcom.net>
>To: e.hoyt@virginnet.co.uk, pita@whale.wheelock.edu
>Subject: Fresh water whales?
>Date: Tue, Apr 3, 2001, 8:02 PM
>

> Hi Dr. Hoyt:
>
> Has anyone ever discovered a fresh water whale, and if not, is the
> salt content of the ocean an important factor?
>
> Thanks, Carolynn Schmahl

Dear Carolyn,

Indeed, some species of cetacea--the order of whales, dolphins and
porpoises--have adapted to living in rivers and lakes.

There are a group of dolphins called river dolphins, which include Amazon
river dolphins (boto), Yangtze river dolphins (baiji), and Indian river
dolphins (susu) which spend their lives in rivers from the ocean.

There are also a number of typically oceanic dolphins, populations of which
spend their lives in fresh water:

Irrawaddy dolphins, tucuxi dolphins, and finless porpoises.

Beluga whales spend a lot of time in rivers and rivermouths. The St.
Lawrence population of belugas lives full time in the river. Other whales,
humpbacks, fins and even blues come up into the river, though typically not
as far upriver as belugas. Of course this river being so broad, it has a
higher salt content than most rivers, but I believe the critical factor is
simply its size and the presence of large amounts of krill, fish and other
food that the whales feed on.

There are some amazing cases of orcas, for example, swimming far upriver. A
humpback whale spent a few pleasant weeks feeding far up the River Clyde
near Glasgow, a few years ago. Gray whales have taken mis-turns (perhaps)
and gone up rivers in the Northwest.

But none of these larger species typically live in rivers for very long.

To find out more about some of the fascinating species mentioned, check the
species/classification information page:
(http://whale.wheelock.edu/whalenet-stuff/classifications.html)

Sincerely,

Erich Hoyt



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