INTRODUCTION TO THE FRESHWATER FISHES OF BRITISH COLUMBIA
Professor, Department of Zoology, University of British Columbia
Director, Beaty Biodiversity Museum
freshwater fishes of British Columbia (BC) consist of 67 native
species and 15 introduced species. By comparison, Ontario has 131 native
species and at least 28 introduced species. “Freshwater” species
either spend their entire lives in freshwater or may spend time feeding
in salt water before returning to freshwater to spawn. The latter are
known as anadromous fishes (e.g., Pacific salmon). Other species that
reproduce in salt water, but spend time feeding in fresh water are
known as catadromous fishes (e.g., American eel), but BC contains no
most diverse group of freshwater fishes in BC is the Salmonidae – the
salmon, trout, char, grayling, and whitefishes – with some 22 species
(of which three are introduced). The least diverse are the
trout-perches (Percopsidae), pikes (Esocidae), and cods (Gadidae) each
with one species.
Origin of the BC freshwater fish fauna
first “record” of freshwater fishes in BC dates back to about 50
million years ago (mya) and is associated with the discovery of the
fossil salmonid fish, Eosalmo driftwoodensis, the specific name stemming from its discovery near the Driftwood River in BC’s central interior. The
ancestry of BC’s freshwater fishes, however, dates back much farther
into the mists of time. The lampreys, of which BC has four species, are
descendants of one of the very earliest lineages of vertebrates, a
lineage that split from the rest of the vertebrates at least 500 mya.
Also, many of the extant families of BC freshwater fishes date to at
least 65 million years ago in North America. The first fossils that are
clearly recognizable as the same as living fishes (e.g., white
sturgeon and cutthroat trout) have been dated to about 5 mya, in the
Pliocene. At the other end of the time continuum are native species
that are probably less than 10,000 years old. The world-famous
“benthic” and “limnetic” species pairs of threespine sticklebacks (part
of the Gasterosteus aculeatus species complex) are found in
four lakes southwestern BC and are considered to have evolved since the
retreat of the Wisconsinan glaciers.
Biogeography of the BC freshwater fish fauna
history of the BC freshwater fish fauna has been heavily influenced by
four processes, three of which are driven by geography:
mountain-building, volcanism, glaciation, and human activity. The first
three extent back millions of years and continue to the present day;
the most serious human activities are limited to the past 200 years or
so (the “Anthropocene” see below).
and shifting of the Rocky Mountains and the Coastal/Insular mountain
ranges concentrated between 33 and 65 mya set the major pattern of
river flow in BC; the predominate eastern (Peace and Liard rivers as
part of the Mackenzie River system) and western-flowing (all other
river systems) drainages. Extensive volcanism from 23 – 3 mya helped to
produce the heavily sculpted waterscapes of the central interior of BC.
Finally, the Wisconsinan glaciation, one of up to 20 that occurred
during the Pleistocene, lasted from about 85,000 to ~11,000 years ago
and covered virtually all of BC with ice sheets up to 3 km thick which
eliminated all of the habitat for freshwater fishes. Consequently, the
current native fish diversity of BC stems almost exclusively from
post-glacial immigration of fishes that survived glaciation in ice free
areas north, west, east, and south of the ice sheets (known as
were three principal glacial refugia that provided postglacial
immigrants to BC via now extinct inter-watershed connections: the
Bering Refuge (unglaciated areas of the Yukon River valley and adjacent
areas of eastern Russia), the Pacific Refuge (unglaciated areas of the
lower Columbia River valley and adjacent areas), and the Great Plains
Refuge (unglaciated areas of the upper Missouri River east of the
Continental Divide). The Pacific Refuge is thought to have provided the
greatest source of postglacial immigrants (about 37 species). Some
fishes in BC (e.g., the stickleback species pairs, the Salish sucker
and the Nooksack dace) and considerable intraspecific diversity (e.g.,
the thousands of genetically distinct salmon and trout populations) are
considered to have evolved in situ since the end of the last glaciation and are, in this sense, “made in BC biodiversity”.
one way in which we organize BC’s freshwater fish biodiversity is by
the major watersheds that share a high proportion of fish species: the
upper Yukon River, the Mackenzie River, the upper Columbia River, the
Fraser River, the Central Coast, the North Coast, Vancouver Island, and
the Queen Charlotte Islands. The Mackenzie River system is the largest
in BC at about 260,000 km2 and the Queen Charlotte Islands is the smallest drainage area at 14,500 km2.
The Fraser River system has the largest number of native species (42)
while the Queen Charlotte Islands has the lowest number (14 species)
“Anthropocene” has been defined informally as that period in
geological time when humans began having a profound effect on Earth’s
ecosystems (commonly, but not universally accepted to begin at the
start of the Industrial Revolution). In BC, one of the most profound
effects of the Anthropocene has been the introduction of non-native
fishes. Such introductions threaten the persistence of native species
and disrupt the historical faunal relationships as part of Canada’s
bioheritage (see Taylor 2004). The Columbia River has the highest number
(16) of non-native species, while the Queen Charlotte Islands and the
upper Yukon River have, thankfully, no non-native species.
contrast, there are, as yet, no known extinctions of BC’s freshwater
fish species at least at the level of full species. There have,
however, been several important extinctions of BC’s freshwater fish
biodiversity; the extinction of all of the innumerable Chinook salmon
populations from vast areas of the upper Columbia River after completion
of the the Grand Coulee Dam in Washington State in 1942 (David
Thompson remarked on rotting carcasses on the shores of Columbia Lake!)
and of the Hadley Lake (Lasqueti Island) stickleback species pair are
BC’s freshwater fish species at risk
Recognizing the effects of the Anthropocene on BC’s native fish diversity, the Canadian Species at Risk Act (enacted
in 2003) seeks to assess which species are at risk and to affect their
recovery. British Columbia currently has 27 species (and several
population groups within these species) that have been assessed as
Extinct or at some level of risk of extinction (“Extirpated”,
“Endangered”, “Threatened”, or “Special Concern”) – the second highest
in number in Canada (Ontario has the most). For example, the Hadley
Lake stickleback species pair has been assessed as Extinct, the Nooksack
dace as Endangered, the lower Fraser River population of White
Sturgeon as Threatened, and the Columbia Sculpin as Special Concern
(see http://www.registrelep-sararegistry.gc.ca/species/default_e.cfm# for more information). Several salmon populations have been assessed at
some level of risk as well (e.g., Okanagan Chinook salmon, Cutltus
Lake sockeye salmon, Thompson River coho salmon). The principle threats
to BC’s freshwater fishes are habitat loss and degradation and
non-native and harmful (i.e., “invasive”) species (see Dextrase and
Mandrak 2006). The BC Fish Protection Act (1997) also seeks to
protect BC’s fishes and their habitats, and ongoing commitments are
required by all to ensure the persistence of our unique freshwater fish
1The text herein is based heavily on the excellent reviews provided in McPhail and Carveth (1994) and McPhail (2007).
Dextrase, A. and N. Mandrak. 2006. Impacts of alien invasive species on freshwater fauna at risk in Canada. Biological Invasions 8: 13–24.
McPhail, J. D., and R. Carveth. 1994. Field key to the freshwater fishes of British Columbia. Resources Inventory Council, Province of BC.
McPhail, J. D. 2007. Freshwater fishes of British Columbia. University of Alberta Press, Edmonton.
E.B. 2004. An analysis of homogenization and differentiation of
Canadian freshwater fish faunas with an emphasis on British Columbia. Canadian. Journal of Fisheries and Aquatic Science 61: 68-79.
Please cite these pages as:
Author, Date. Page title. In Klinkenberg, Brian. (Editor)
2020. Biodiversity of British Columbia [www.biodiversity.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of
British Columbia, Vancouver.
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