Introduced
Species Summary Project
Atlantic Salmon, (Salmo salar)
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Scientific Name: Salmo salar
Classification:
Phylum or
Division: Chordata
Class: Osteichthyes
Order: Salmoniformes
Family: Salmonidae
Original Distribution: Northern
Atlantic Ocean
Current Distribution: Atlantic
& Pacific, off northwest coast of North America and in rivers of British
Columbia and northwest US
Site and
Date of Introduction: Pacific coast of British Columbia and Washington and
Alaska, and rivers and streams along that coast. Introduced prior to 1990s, but increased significantly in early
1990s.
Mode(s) of Introduction: Through
planned and unplanned escapes from fish farms, although species indigenous to
the pacific are also escaping from fish farms.
Reason(s)
Why it has Become Established: Planned escapes were to
study viability of hybrid progeny; however the population has not successfully
established itself. All Atlantic salmon
caught are thought to be escapees, whether planned or unplanned. Approximately
10,000 fish escaped in 1993.
Ecological Role: In 1996
Atlantic salmon escapees constituted 0.004% of the yearly Pacific salmon
catch. Farmed salmon continue to escape
from pens on an ongoing basis and to appear in the ocean, rivers and streams,
evidently attempting to spawn, though no successful incidence of this has yet
been recorded.
Benefit(s):
Commercial fishing – minimal yield to date, although there have been landings
of 864 fish per year in early 1990s, except 1993 when it was higher due to a
higher number of escapes.
Threat(s): There is a potential fear of
genetic alteration of native populations, including alterations that may
threaten viability of native species which might reduce fitness and disrupt
genetic diversity. There is also a
possibility of interbreeding, competition, disease and parasitism; however,
these things have so far not occurred.
Control Level Diagnosis: Minimal
priority. Considering the
difficulty of producing viable hybrid progeny in the lab crossing Atlantic with
Pacific salmon, the threat to native populations is somewhat in abeyance via
interbreeding. To date, there is no
evidence that Atlantic salmon have reproduced in the wild among themselves or
with others, though it is expected they will try to spawn amongst themselves
(there is a greater probability of successful breeding with native populations
by indigenous Pacific salmon escaping from fish farms into the wild);
conversely, there is no significant benefit deriving from the presence of these
fish on the west coast, so their artificial presence, potentially disruptive,
might as well be terminated. Though projected threats have so far not
materialized, there is no reason to incur these risks. Repeated failures to introduce Atlantic
Salmon in this region and continued high mortality suggest that there is little
threat either of interbreeding or challenging indigenous populations.
Control Method: Stop introducing them in Pacific fish farms. Stop escapes from fish farms of the existing
population by terminating planned escapes and by eating or selling the Atlantic
salmon on hand. If there is no further
importation, it should put a stop to their presence in the Pacific northwest.
References:
Impacts of farmed salmon escaping from net pens, (British
Columbia. Environmental Assessment
Office : http://www.eao.gov.bc.ca/project/aquacult/salmon/escape.htm
[1997])
Taxonomy of Atlantic Salmon (Atlantic Salmon Federation : http://www.asf.ca/Overall/taxonomy.html
[1997?])
Author: Kevin
Mathewson
Last Edited: February 25, 2002
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Project Editor: James A. Danoff-Burg, Columbia University