Acipenser transmontanus

Identification Tips:

• Top lobe of caudal (tail) fin is much longer than bottom lobe
• Rows of bony plates (scutes) along the back and sides
• Large broad head with small eyes,
• 4 barbels in front of mouth
• Dorsal fin: 44 - 48 soft rays
• Anal fin: 28 - 31soft rays
• May exceed 4 m in length (historical record of 6 m from lower Fraser River)
• Grey, pale olive or grey-brown above to grey or white below

Conservation Status:

British ColumbiaCanadaNatureserve
COSEWICSpecies at Risk Act
Red ListThreatenedNoneG4, S2

Information Source: BC Conservation Data Centre: http://a100.gov.bc.ca/pub/eswp/

Life History:

The world's largest freshwater fish
• Bottom feeder; juveniles feed on aquatic insect larvae, crustaceans, and molluscs; adults feeding on mainly fish
• Spawn during high flows of freshet May - July
• Males mature by 1 years, females by 20 years
• May live more than 100 years

Habitat:

• Most adults are permanent residents of large river channels
• Juveniles rear in estuary or side channels
• Spawn in side channels over gravel or sand substrates in currents greater than 1.5 m/s

Range:

British Columbia
• Breeding populations limited to main stems of Fraser and Columbia Rivers and their largest tributaries
• Adults occasionally found in sea and estuaries of Vancouver Island

Global
• Large rivers, estuaries and inshore marine waters from Gulf of Alaska to Monterey, California.

Comments:

• There are 6 distinct populations recognized in British Columbia
• The Lower Fraser River population is the only one not currently listed as Endangered by COSEWIC and under the Species at Risk Act
• They too may be in decline, as fewer juvenile fish are being encountered than in the past.

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Primary Information Source:
McPhail, J.D. 2007. The Freshwater Fishes of British Columbia. University of Alberta Press. Edmonton, Alberta.