|
The only naturally occurring species of salmon in
the Atlantic Ocean is the Atlantic salmon (Salmo salar). It is found
in rivers of the lands bordering on the North Atlantic Ocean from Connecticut
in the USA, north through Canada, in Greenland and Iceland, throughout
Scandinavia and Eastern Russia, and south all the way to Portugal.
Pacific salmon naturally occur in the rivers draining
to the Northern hemisphere in the Pacific Ocean. There are numerous
species: sockeye salmon, pink salmon, chum salmon,coho salmon, chinook
salmon, masu salmon and the amago salmon. Many people now also consider
the rainbow trout to be a Pacific salmon.
One important difference between Atlantic and Pacific
salmon is that most of the Pacific salmon (the exception is the Rainbow
trout) die right after spawning, whereas many Atlantic salmon will survive
to spawn two or more times. The carcasses of the dead Pacific salmon
act as a fertilizer for the streams and surrounding forest. This may
be one of the reasons why Pacific salmon populations are generally much
larger than Atlantic salmon populations in similar sized rivers. The
forest gets fertilized when grizzly bears catch salmon, eat part of
the body up on shore, then leave the rest in the forest when they go
back for a better fish. There are no grizzly bears on the East Coast,
but Black bears will eat Atlantic salmon there. However, we do not think
that they ever catch enough to really fertilize the forest.
Sea run rainbow trout are very much like Atlantic
salmon. Their juveniles are territorial and live in fresh water, and
the adults will undergo a long ocean migration with a return to their
home river. The rainbow is the only one of the Pacific salmon that does
not automatically die after spawning. Some will survive and come back
to spawn again in the future. Males of this and other Pacific salmon
species will develop kypes (hooked toothed jaws) just like Atlantic
salmon during the spawning season.
Man has moved Pacific salmon to the Atlantic Ocean,
and Atlantic salmon to the Pacific Ocean. Sometimes this is to farm
in cages the different species that can then be sold to people. Many
fish are accidentally escaping from these cages. In other cases the
fish were moved deliberately to try and establish new species for anglers
to catch. There is a big danger in doing this. Pacific and Atlantic
salmon could compete with each other for food and places to live. This
could result in neither group developing or maintaining healthy populations.
Nowadays, these exotic species introductions are considered to be very
dangerous.
 Back
to Top
|
 |
