Wild Species 2005: chapter 7


Fish - A vertebrate cold-blooded animal with gills and fins and living wholly in water. - The Canadian Oxford Dictionary.

Image of Yelloweye Rockfish
Photo: Yelloweye Rockfish, (Sebastes ruberrimus) © Fisheries and Oceans Canada

Quick facts

  • There are approximately 29 400 known species of fishes in the world, more than any other type of vertebrate.
  • Nearly 1400 species of fishes are found in Canadian waters, comprising approximately 60% of all Canada's vertebrate species. 11% of Canada's fishes occur in freshwater habitats, 85% occur in marine habitats and 4% are found in both freshwater and marine habitats.
  • A total of 60% of Canada's fish species are ranked Undetermined or Not Assessed. Most of the fishes ranked Undetermined or Not Assessed are marine species, reflecting how much we need to learn about marine ecosystems, particularly in the Arctic.
  • The majority of freshwater fishes have Canada General Status Ranks (Canada ranks) of Secure (64%). However, 10% of freshwater fish species have Canada ranks of At Risk.
  • Of the 206 fishes that received Canada ranks in both 2002 and 2005, 30 species have changed rank since 2002. The majority of these changes (43%), moved species into a category with a lower level of risk. Changes resulted in an increase in the proportion of species ranked Secure.


The fishes are a large and diverse group found in a wide range of habitats, ranging from the depths of the oceans, to constantly changing estuaries, to shallow warm water ponds, to deep, cool lakes and rivers. Modern fishes are split into three major groups; Superclass Agnatha, Class Chondrichthyes and Superclass Osteichthyes (classification from the Integrated Taxonomic Information System). Superclass Agnatha includes the lampreys and hagfishes; primitive, jawless fishes that resemble eels. The sharks, rays, skates, chimera and paddlefishes are classified in Class Chondrichthyes. These species all have skeletons made of tough cartilage instead of bone. Finally, Superclass Osteichthyes includes fishes with bony skeletons, and comprises the majority of living fishes. Roughly half of the known vertebrate species in the world belong to Superclass Osteichthyes!

Fishes come in all shapes and sizes, from the enormous Greenland shark (Somniosus microcephalus), to the curious and primitive lampreys (family Petromyzontidae), to the torpedo shaped tunas (family Scombridae). However, all fishes share certain common features. For example, all fishes live underwater, and breathe by moving water over their gills, where dissolved oxygen passes into the blood and carbon dioxide passes back out. Most fishes are cold-blooded (ectothermic) meaning their body temperature is determined by the surrounding water temperature. Fishes propel themselves through the water by weaving movements of their body and tail, and control their direction by means of fins. All fishes cover their skin with slimy glandular secretions, and nearly all have scales. Together, the slime and scales provide a smooth, nearly waterproof coating, which reduces friction and allows the fish to glide smoothly through the water. All fishes have a system of sense organs in the skin, collectively called the lateral line system. The lateral line system is sensitive to changes in water pressure, which can be generated by movement in the water, or when a fish changes depth or approaches a stationary object. This information helps fishes navigate their three-dimensional, underwater world.

Fishes eat a variety of food types, from algae and vascular plants to invertebrates and other fishes. In most species, diet changes with age, so that juvenile and adults feed on very different types of food, and few species of fish specialize on only one food source. Fishes show many adaptations to aid them in finding and capturing food. For example, active predators like tunas and some sharks (e.g. family Lamnidae), have very streamlined bodies and are capable of swimming at high speeds for fairly long periods of time, in order to chase down their prey. On the other hand, some lie-in-wait predators like Northern Pike (Esox lucius) and Spotted Gar (Lepisosteus oculatus) have long flexible bodies, long, grasping mouths and rely on a short burst of speed once the prey has wandered within reach. Fishes that feed at the water's surface, like Blackstripe Topminnow (Fundulus notatus), generally have upward pointing mouths, whereas fishes that feed on the bottom, like the Channel Catfish (Ictalurus punctatus) often have mouths on the underside of their head, as well as barbels or whiskers that help them sense food in dark or murky water. Other fishes specialize in feeding on plankton, tiny plants (phytoplankton) and animals (zooplankton) that float in the water (e.g. Paddlefish, Polyodon spathula; herrings, family Clupeidae). These fishes filter the plankton from the water using sieve-like gill rakers under their operculum.

Fishes have developed a variety of methods of reproduction. Most fish species are gonochoristic, meaning that they have separate male and female individuals, but some species are hermaphroditic, meaning that individual fishes can change from one sex to the other during their lifetime (e.g. seabasses, family Serranidae). The majority of fish species lay eggs and provide very little care for their young. For example, male and female Lake Whitefish (Coregonus clupeaformis) gather in large schools to release eggs and sperm into the water, with little regard for what happens to the eggs or young afterwards. This is known as 'broadcast spawning'. Species that provide little parental investment, tend to produce large numbers of eggs, to increase the chance that some will survive. For example, the broadcast spawner, White Hake (Urophycis tenuis) can release more than 3 000 000 eggs per female! Other species produce far fewer eggs, but invest more energy into choosing a mate and caring for the eggs and young. For example, male Threespine Sticklebacks (Gasterosteus aculeatus) build a 'nest' of aquatic vegetation, and use elaborate courtship rituals to attract a mate. Females lay eggs in the nest, before being chased away by the male, who tends first the eggs and then the young, until they are independent. Rays and some species of sharks provide their eggs with additional protection by enclosing them in leathery egg cases or purses. The purses can lie on the bottom for a year or more before the eggs hatch. Most species of sharks take the protection of their young a step further, by giving birth to live young (fully formed juveniles). This allows the mother to provide the developing embryos with a stable environment and protect them from predation, but in general very little care is provided once the young are born. Fishes that produce live young typically use internal fertilization, as do mammals and birds.

Status of knowledge

Knowledge of Canadian fishes varies quite widely by species. Species that are important for commercial fisheries, such as Lake Whitefish, Pacific salmon species and Atlantic Cod (Gadus morhua), and recreationally sought species, such as Walleye (Sander vitreus), have been particularly well studied, and much is known about their biology and ecology. Species of particular scientific interest or importance have also been well studied. For example, members of the stickleback family (Gasterosteidae) have been used to study reproductive behaviour, feeding behaviour and adaptations, diet, effects of pollution, life history, predation, competition, natural selection and genetics. In addition, some exotic species have also been relatively well studied, due to the damage they can cause to native communities and species. However, species outside these categories are less well understood, particularly marine fishes that live in deep water or in the Arctic Ocean.

Many research projects are ongoing in Canada, as scientists work towards filling the gaps in our understanding of fishes. The Pacific Ocean Shelf Tracking Project, or POST, uses an array of listening stations set along the west coast of North America to monitor the movement of marine animals. POST results will give much needed information about little known aspects of the biology of threatened and commercially valued species, and provide unprecedented insight into fish migration. On the east coast, the Centre for Marine Biodiversity is investigating the links between fisheries and habitat and the impacts of exotic species on marine fishes, among other topics. Recent research has focused on studying all species in an ecosystem, in order to understand how an ecosystem functions. This will provide the information necessary to manage fisheries and other activities in a more sustainable manner.

Richness and diversity in Canada

The distribution of Canada's fishes is governed by many factors including salinity (the amount of salt in the water), temperature, and habitat availability to name only a few. There are roughly 1389 species of fish found in Canadian waters, the majority of which are found only in marine waters (1178 species). The number of species occurring only in freshwater 160 species), or in both marine and freshwater 51 species) is much lower.

Of the provinces and territories, Ontario has by far the highest diversity of fish species (154 species), followed by Quebec (117 species, Figure 2-6-i, Table 2-6-i). Many of Ontario's freshwater species are warmwater species found only in the south of the province, and typically have most of their range in the United States. Although the territories have lower species richness than the provinces, many of the fishes found in the territories are coldwater species that have limited or no range in southern Canada or the continental United States (e.g. Broad Whitefish, Coregonus nasus Least Cisco, Coregonus sardinella).

Canada's marine waters are predominantly the inshore and continental shelf components of the ocean, which are nutrient rich and highly productive. Canada's Atlantic seaboard, with its massive shelf varying in width from 110 to 520 km from shore, supports a high level of species diversity (835 species, Figure 2-6-i, Table 2-6-i). By comparison, the shelves of the Pacific and Arctic seaboards are much narrower, at about 65 km wide, and support lower species diversity.

Species spotlight - Arctic Char Salvelinus alpinus

Arctic Char (Canada General Status Rank: Secure), are closely related to the salmons and trouts and inhabit cold rivers, lakes and streams across Canada. This large and often colourful fish is an example of an anadromous species; that is, a fish that migrates between freshwater (where they spawn) and marine water (where they feed and grow). Arctic Char have the most northerly distribution of any Canadian freshwater fish, and are native to the Yukon Territory, the Northwest Territories, and Nunavut, as well as the eastern and western Arctic Ocean regions, the Atlantic Ocean region, Manitoba, Ontario, Quebec, New Brunswick, and Newfoundland and Labrador.

Arctic Char have two main life history variations; those that migrate between freshwater and marine habitats (sea-run) and those that remain permanently in freshwater. In the Arctic, marine habitats are much richer in nutrients than freshwater habitats, so food is more readily available in the sea than in freshwater. Sea-run Arctic Char take advantage of this by spending the summer feeding in the ocean, then migrating back to freshwater in the fall, before the ocean freezes. Searun Arctic Char then overwinter in freshwater, typically in the bottom of deep lakes, before migrating back to sea the next spring.

As their name suggests, freshwater Arctic Char remain in freshwater year round, living in lakes or rivers. Freshwater Artic Char grow much more slowly, and are typically much smaller than searun Arctic Char. However, freshwater Arctic Char become sexually mature much more rapidly than sea-run Arctic Char (one to three years for freshwater individuals vs. 10 to 25 years for searun individuals). These different life histories provide a fascinating puzzle for scientists, particularly since, in some parts of the Arctic, both varieties of Arctic Char can be found in the same lake. Scientists are also studying how climate change may impact the relative numbers and success of the sea-run and freshwater Arctic Char.

Arctic Char has been an important food source for northern communities for centuries. More recently, Arctic Char sportfishing has become commercially important in northern Canada, and Arctic Char aquaculture operations have developed in southern Canada. Arctic Char is an expensive delicacy, prized even above the best salmon.

Species spotlight: Skates - family Rajidae

The skates, together with the sharks and rays, belong to the class Chondrichthyes. Like all Chondrichthyes, skates have a skeleton made of cartilage, which is tough, supple and half as dense as bone, making skates light-weight and flexible. Skates have flattened, disc-like bodies and characteristic broad pectoral fins or 'wings'. They swim by gently undulating their fins, so that they appear to fly through the water, while the long, thin tail acts as a rudder. Most skates are bottom dwellers, sometimes lying partially buried in sand or gravel. The mouth and gills are situated on the under-side of the fish, and two breathing holes, or spiracles, are situated on the upper-side. Skates breathe by inhaling water through the spiracles and expelling it through the gills. Their carnivorous diet consists of crabs, shrimps, small crustaceans, small fishes, and cephalopods (squid and octopus). A skate typically cannot capture active animals by a direct attack because of the position of its mouth on the under-side of its body; instead it captures prey by darting forward suddenly and settling down over its prey.

There are over 100 recognized species of skates worldwide, of which 29 are known to occur in Canadian waters. The most common species in eastern Canadian waters is the Thorny Skate (Amblyraja radiata). Thorny Skates are brown to gray and are thornier than other species of skates. They can live to at least 16 years and may grow to a length of 100-110 cm. Thorny Skates live in cold water (mainly 2-7°C) at a range of depths, from about 20 - 1000 m. Globally, populations of several different skate species, including Thorny Skate, have been showing evidence of population declines. The Thorny Skate has a Canada General Status Rank (Canada rank) of May Be At Risk.

Species spotlight: Rockfish - genus Sebastes

Rockfishes are members of the large Scorpionfish family or Scorpaenidae. There are 42 species of rockfish found in Canadian waters including 38 species found only in the Pacific Ocean region, two species found only in the Atlantic Ocean region and two species found in both the Atlantic Ocean region and the eastern Arctic Ocean region. Rockfishes come in a variety of shapes, sizes and colours, but all have certain characteristics in common, including large mouths, prominent, mildly poisonous spines along the back, and smaller spines on the head. Rockfishes reproduce using internal fertilization and bear live young. They tend to be slow-growing, long-lived, mature at a late age and have highly variable recruitment success. An extreme example is the Yelloweye Rockfish (Sebastes ruberrimus) which reaches sexual maturity at approximately 18 years of age and can live in excess of 110 years! These extreme life history traits lead to low population growth, making rockfish populations vulnerable to increased adult mortality, such as fishing.

These fascinating creatures are highly sought after, because they are delicious to eat. Recent monitoring and research programs have indicated that some rockfish stocks in the Strait of Georgia, off Canada's west coast, are at low levels of abundance as a result of harvesting pressure from commercial, recreational and Aboriginal fisheries. Due to growing concerns over rockfish declines, Fisheries and Oceans Canada announced a Rockfish Conservation Strategy in 2002, which included new regulations limiting both commercial and recreational catch of rockfishes, as well as the establishment of Rockfish Conservation Areas (RCA). The intention of the RCAs is to protect rockfish habitat, minimize mortality from directed and incidental fisheries, and allow for the rebuilding of rockfish stocks. Most of Canada's rockfishes have Canada ranks of Undetermined or Sensitive, but one species (Bocaccio, Sebastes paucispinis) has a Canada rank of At Risk, and three species have Canada ranks of May Be At Risk.

Results of assessment

Most of Canada's 1389 species of fishes have Canada ranks of Not Assessed (434 species, 31%) or Undetermined (395 species, 28%), while only 17% are ranked Secure (238 species, Figures 2-6-i, 2-6-ii, Table 2-6-i). However, all of the species ranked Not Assessed and most the species ranked Undetermined (391 species) are marine species (Table 2-6-ii). These species generally have a large part of their range in the Arctic Ocean, where little data are available on distribution, population size or threats, or are species commonly found in deep-water, which is not adequately covered by current research programs.

It is important to note that when marine species occur in multiple ocean regions, the Canada rank is often based on the ocean region where its status is best understood. For example, the Pacific Sand Lance (Ammodytes hexapterus), occurs in the Pacific Ocean Region (Secure), the Western Arctic Ocean Region (Not Assessed) and the Eastern Arctic Ocean Region (Not Assessed). The Canada rank for this species is Secure, based on the Pacific Ocean Region rank, but it is possible that a more thorough analysis of the species' status in the Arctic may lead to a national status change in the future.

If Canada's 1178 species of marine fishes are considered separately from both the freshwater fishes, and fishes that are ranked in both freshwater and in the ocean regions, a total of 70% of species have Canada ranks of Undetermined (391 species) or Not Assessed (434 species), reflecting how much we need to learn about marine systems (Figure 2-6-iii, Table 2-6-ii). In addition, 17% of marine fishes have Canada ranks of Accidental (200 species), 8% have Canada ranks of Secure (94 species), 3% have Canada ranks of Sensitive (41 species), and a total of 2% have Canada ranks of May Be At Risk (11 species) and At Risk (seven species).

The situation is quite different for freshwater fish species (Figure 2-6-iii, Table 2-6-ii). Only 2% of freshwater fishes have Canada ranks of Undetermined (three species), and none have Canada ranks of Not Assessed. The majority of freshwater species are ranked Secure (64%, 103 species), while 13% are ranked Sensitive (20 species), 10% are ranked At Risk (16 species) and 2% are ranked May Be At Risk (three species). Two freshwater fish species, Gravel Chub (Erimystax x-punctatus) and Paddlefish are ranked Extirpated and one species, Deepwater Cisco (Coregonus johannae) is ranked Extinct. All three of these species were formerly found in Ontario. Finally, 8% of freshwater fish species are ranked Exotic (12 species).

Fishes ranked in both freshwater and marine regions (51 species) show a similar pattern to freshwater fishes; 80% of these species have Canada ranks of Secure (41 species), 8% have Canada ranks of Sensitive (four species), 6% have ranks of At Risk (three species) and 4% have Canada ranks of May Be At Risk (two species Figure 2-6-iii, Table 2-6-ii). Only 2% have a Canada rank of Undetermined (one species).

Figure 2-6-i: Summary of the species richness and 2005 general status ranks of fish species in Canada. PAC = Pacific Ocean, WAO = Western Arctic Ocean, EAO = Eastern Arctic Ocean and ATL = Atlantic Ocean.
bar chart (see long description below)
Long description for Figure 2-6-i

Figure 2-6-i illustrates the total number of fish species in Canada and per region, broken down into rank status. In Canada there were 2 extirpated, 1 extinct, 26 at risk, 16 may be at risk, 65 sensitive, 238 secure, 395 undetermined, 434 not assessed, 12 exotic and 200 accidental species for a total of 1389 fish species. Among these, in the Yukon there were 3 species that were sensitive, 18 secure, 12 undetermined, 1 not assessed, and 2 exotic for a total of 36 species. In the Northwest Territories there was 1 species at risk, 1 that may be at risk, 9 sensitive, 13 secure, 18 undetermined, 2 not assessed, and 5 accidental for a total of 49 species. In Nunavut there were 4 species that were sensitive, 7 secure, 11 undetermined, and 2 not assessed for a total of 24 species. In British Columbia there were 4 species at risk, 10 may be at risk, 7 sensitive, 43 secure, 3 undetermined, and 14 exotic for a total of 81 species. In Alberta there were 5 at risk species, 2 may be at risk, 7 sensitive, 26 secure, 11 undetermined, 1 not assessed, and 9 exotic species for a total of 61 species. In Saskatchewan there were 6 species at risk, 4 may be at risk, 15 sensitive, 32 secure, 17 exotic and 1 accidental species for a total of 75 species. In Manitoba there were 3 species at risk, 9 may be at risk, 8 sensitive, 60 secure, 1 undetermined, 1 not assessed, and 9 exotic for a total of 91 species. In Ontario there were 5 extirpated species, 1 extinct, 10 at risk, 3 may be at risk, 21 sensitive, 86 secure, 7 undetermined, 1 not assessed, and 20 exotic for a total of 154 species. In Quebec there was 1 extinct species, 1 at risk, 11 may be at risk, 15 sensitive, 76 secure, 1 undetermined, 1 not assessed, 10 exotic, and 1 accidental for a total of 117 species. In New Brunswick there was 1 species at risk, 5 sensitive, 37 secure, 1 undetermined, 1 not assessed, and 6 exotic for a total of 51 species. In Nova Scotia there were 2 species at risk, 3 may be at risk, 5 sensitive, 23 secure, 1 undetermined, 1 not assessed, and 7 exotic for a total of 42 species. In Prince Edward Island there was 1 species at risk, 2 may be at risk, 2 sensitive, 12 secure, 1 undetermined, 1 not assessed, 5 exotic, and 3 accidental for a total of 27 species. In Newfoundland and Labrador there were 4 species that were sensitive, 18 secure, 6 undetermined, 1 not assessed, 2 exotic, and 1 accidental for a total of 32 species. In the Pacific Ocean Region there were 2 species at risk, 7 may be at risk, 23 sensitive, 75 secure, 275 undetermined, 3 not assessed, and 40 accidental for a total of 425 species. In the Eastern Arctic Ocean Region there were 2 species at risk, 4 sensitive, 6 secure, 13 undetermined, and 130 not assessed for a total of 155 species. In the Western Arctic Ocean Region there was 1 species at risk, 1 sensitive, 9 secure, 6 undetermined, 50 not assessed, and 4 accidental for a total of 71 species. In the Atlantic Ocean Region there were 8 species at risk, 11 may be at risk, 24 sensitive, 55 secure, 135 undetermined, 430 not assessed, and 172 accidental for a total of 835 species.


Table 2-6-i: Summary of the 2005 general status ranks of fishes in Canada. PAC = Pacific Ocean, WAO = Western Arctic Ocean, EAO = Eastern Arctic Ocean and ATL = Atlantic Ocean.
Extirpated 2 0 0 0 0 0 0 0 5 0 0 0 0 0 0 0 0 0
Extinct 1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0
At risk 26 0 1 0 4 5 6 3 10 1 1 2 1 0 2 2 1 8
May be at risk 16 0 1 0 10 2 4 9 3 11 0 3 2 0 7 0 0 11
Sensitive 65 3 9 4 7 7 15 8 21 15 5 5 2 4 23 4 1 24
Secure 238 18 13 7 43 26 32 60 86 76 37 23 12 18 75 6 9 55
Undetermined 395 12 18 11 3 11 0 1 7 1 1 1 1 6 275 13 6 135
Not assessed 434 1 2 2 0 1 0 1 1 1 1 1 1 1 3 130 50 430
Exotic 12 2 0 0 14 9 17 9 20 10 6 7 5 2 0 0 0 0
Accidental 200 2 5 0 0 0 1 0 0 1 0 0 3 1 40 0 4 172
Total 1389 36 49 24 81 61 75 91 154 117 51 42 27 32 425 155 71 835
Figure 2-6-iii: Comparison of the 2005 Canada General Status Ranks (Canada ranks) of fishes, by habitat. (A = marine species, ranked only in ocean regions B = freshwater species, ranked only in provinces/territories C = species ranked in both ocean regions and provinces and territories).
bar chart (see long description below)
Long description for Figure 2-6-iii

Figure 2-6-iii illustrates the general status ranks, as a percentage, of fishes by habitat (Marine species, Freshwater species, and species ranked in both ocean regions and provinces and territories). For Marine fishes in all of Canada, 1% of species were ranked may be at risk, 4% sensitive, 8% secure, 33% undetermined, 37% not assessed, and 17% accidental. For Freshwater fishes, 1% of species were ranked extinct, 1% extirpated, 10% at risk, 2% may be at risk, 13% sensitive, 64% secure, 2% undetermined and 8% exotic. For species ranked in both marine and freshwater habitats, 6% of species were ranked at risk, 4% may be at risk, 8% sensitive, 80% secure and 2% were undetermined.

Table 2-6-ii: Comparison of the 2005 Canada General Status Ranks (Canada ranks) of fishes in Canada, by habitat.
Canada Rank Marine species, ranked only in ocean regions Freshwater species, ranked only in provinces/territories Species ranked in both ocean regions and provinces and territories
Extinct 0 1 0
Extirpated 0 2 0
At Risk 7 16 3
May be at risk 11 3 2
Sensitive 41 20 4
Secure 94 103 41
Undetermined 391 3 1
Not Assessed 434 0 0
Exotic 0 12 0
Accidental 200 0 0
Total 1178 160 51

Comparison with 2002 ranks

Freshwater fishes were first ranked at the provincial and territorial level, in Wild Species 2000. However, at that time, Canada ranks were not completed. In 2002, the National General Status Working Group completed the Canada ranks for the 232 freshwater fishes listed in Canada, based solely on the provincial and territorial ranks published in Wild Species 2000.

Since 2002, 26 species have been removed from the list of Canadian freshwater fish species, due to new publications that have clarified the taxonomy and distribution of North American fishes. This leaves a total of 206 species that were ranked both in 2002 and 2005. In 2000 and 2002, fishes were ranked solely on the basis of their occurrence and status in freshwater. However, many of these species occur both in freshwater and in marine habitats. Therefore, 49 species that were originally ranked only in the provinces and territories now have ocean region ranks as well. The Canada ranks for the majority of these species (84%) have not changed since 2002. Of the eight species whose Canada rank has changed (16%), five were procedural changesFootnote1 and three changes were due to new COSEWIC assessments.

Of the remaining 157 species, that were ranked only in freshwater in both 2002 and 2005, 22 species have been given a different Canada rank in 2005 (14%). Eleven of these changes were procedural changes (45%), six were due to new COSEWIC assessments (27%), two were due to improved information about the species (9%), one was due to a combination of procedural changes and new information (5%), one was due to a combination of new/improved information and biological change (5%), and one was due to biological change (5%).

In total, 30 changes were made to Canada ranks of fishes, of which eight resulted in an increased level of risk and 13 resulted in a reduced level of risk (Table 2-6-iii). The remaining nine changes moved species out of the Undetermined, Not Assessed, Accidental or Extirpated/Extinct categories. Changes in the Canada ranks have lead to an increase in the proportion of species ranked Secure (Table 2-6-iv).

Table 2-6-iii: Species summary of Canada General Status Rank (Canada rank) changes, for individual fish species, between 2002 and Wild Species 2005.
2005 Canada
2002 Canada rank English name Scientific name Reason for
At Risk Extirpated/Extinct Shortnose Cisco Coregonus reighardi C
At Risk May be at risk Redside Dace Clinostomus
At Risk May be at risk White Sturgeon Acipenser
At Risk May be at risk Striped Bass Morone saxatilis C
At Risk May be at risk Western Silvery
Hybognathus argyritis C
At Risk May be at risk Speckled Dace Rhinichthys osculus C
May be at risk Undetermined Blackfin Cisco Coregonus nigripinnis I
May be at risk Undetermined Margined Madtom Noturus insignis P
Sensitive At Risk Kiyi Coregonus kiyi P
Sensitive May be at risk Atlantic Sturgeon Acipenser oxyrinchus P
Sensitive May be at risk Silver Lampre Ichthyomyzon
Sensitive Secure American Brook
Lampetra appendix B
Sensitive Secure Chain Pickerel Esox niger P
Sensitive Secure Ghost Shiner Notropis buchanani P
Sensitive Undetermined Bering Cisco Coregonus laurettae C
Secure Sensitive Chiselmouth Acrocheilus
Secure Sensitive Bigmouth Shiner Notropis dorsalis C
Secure Sensitive Dolly Varden Salvelinus malma P
Secure Sensitive Greenside Darter Etheostoma
Secure Sensitive Redbreast Sunfish Lepomis auritus P
Secure Sensitive Arctic Grayling Thymallus arcticus P
Secure Sensitive Bloater Coregonus hoyi P
Secure Sensitive Fourhorn Sculpin Myoxocephalus
Secure Sensitive Atlantic Salmon Salmo salar P
Secure Sensitive Bigmouth Buffalo Ictiobus cyprinellus P
Secure Undetermined Deepwater
Secure Undetermined Pygmy Whitefish Prosopium coulterii P
Secure Undetermined Arctic Lamprey Lampetra
Secure Not Assessed Redfin Pickerel Esox americanus P/I
Undetermined Accidental Flathead Catfish Pylodictis olivaris P

aC: change due to new COSEWIC assessment.
B: change due to biological change in species' population size, distribution or threats.
I: change due to improved knowledge of the species.
P: change due to procedural change.

Table 2-6-iv: Comparison of the Canada General Status Ranks (Canada ranks) of fish species found in freshwater 2002 and Wild Species 2005.
Canada rank Number and
percentage of
species in each
rank in 2002
Number and
percentage of
species in each rank
in Wild Species 2005
of change
Reasons for change
0 7 (3%) -- a - COSEWIC
assessment c
Extinct -- a 1 (<1%) - Taxonomy b
Extirpated -- a 2 (1%) - Taxonomy b
At Risk 22 (9%) 18 (9%) Taxonomy b, COSEWIC
assessment c,
Biological change d
May be at risk 10 (4%) 5 (2%) COSEWIC
assessment c, Process
e, Improved knowledge
f, Combination of
improved knowledge
and biological change
g, Combination of
improved knowledge
and biological change
Sensitive 30 (13%) 23 (11%) Taxonomy b,
Process e, COSEWIC
assessment c,
Biological change d,
Combination of
process and improved
knowledge h
Secure 131 (56%) 142 (69%) Taxonomy b, Secure e,
assessment c,
Improved knowledge f,
New species g,
Combination of
process and improved
knowledge h
Undetermined 10 (4%) 3 (1%) Taxonomy b,
Process e,
New species g
Not Assessed 1 (<1%) 0 Undetermined
Exotic 20 (9%) 12 (6%) Taxonomy b, Improved
knowledge f
Accidental 1 (<1%) 0 Process e

Key to symbols:
↑ Number of species in this category has increased.
↓ Number of species in this category has decreased.
↔ An equal number of species have been added and removed from this category; no net change.
= No species have been added or removed from this category.

a Insérez note a du tableau 1 ici.

b A taxonomical change has lead to the addition or removal of a species from the national list.

c A formal COSEWIC assessment has been conducted, and used as evidence for a change in
rank. A biological change (i.e. a change in species population, distribution or threats) since 2000
is not suggested.

d A biological change in species' population size, distribution, threats or trends has lead to a
change in rank.

e A different process has been used for assigning ranks, leading to a change in the Canada rank.

f New information has been collected or brought to light, and used as evidence for a change in
rank. A biological change (i.e. a change in species population, distribution or threats) since 2000
is not suggested.

Threats to Canadian fishes

Some major threats to fish populations include overfishing, pollution, and climate change. In addition, interactions between wild and farmed species, such as competition for food and habitat, interbreeding and introduction of disease and parasites, continue to be cause for concern. Habitat degradation and destruction are important threats to many fishes. Most fishes use several different habitats during their life cycle, and the loss of any one of those habitats can lead to population declines. Habitat loss, such as wetland drainage, is often a very obvious cause of fish population declines. Habitat degradation, through channelization, damming, siltation, alteration of habitat structure by removal of debris and vegetation, alteration of substrate or ocean floor, or water withdrawal for human use, is often less obvious, but nonetheless an important factor leading to declines in fish populations.

Exotic fishes can have a negative impact on native species and ecosystems through competition, predation, parasitism, introduction of novel diseases or parasites, habitat alterations and hybridization, which can change the genetic structure of native populations. Exotic fishes have been causing problems in Canada for many years. For example, the Sea Lamprey (Petromyzon marinus), which has been an important factor in massive declines in the abundance and diversity of fishes in the Great Lakes, was first found in Lake Erie in 1921. Introductions of Exotic fishes happen in several different ways including deliberate introductions, usually for the purpose of improving commercial or sport-fishing, release or escape of captive fishes from aquariums and fish farms, and the spread of fish populations along new waterways.Exotic fishes have been directly linked to the extinction of at least one species in Canada; the Deepwater Cisco. Attempts to control or eradicate Exotic species are very expensive. For example, Canada and the United States spend millions of dollars a year, to attempt to control Sea Lamprey populations in the Great Lakes region.

One of the most important threats to marine fishes is overfishing. In some areas, recent research suggests that commercial exploitation has brought populations of marine fishes to historically low levels, and may be preventing populations from recovering. Both target species, and non-target species, whose capture is incidental to the commercial fishing operation (by-catch) are impacted by overfishing. In addition, some methods of fishing can impact the population structure and composition of species caught, by selectively catching certain species or age-classes.

The threats discussed so far are immediate and relatively easy to measure and study. However, climate change may prove the greatest overall threat to Canadian fishes. The effects of climate change are difficult to measure or to predict, because it often acts indirectly, through changes in habitat or food supply. Climate change may also increase the negative impact of other threats (e.g. by creating suitable conditions for invasion of Exotic species). Nevertheless, climate change has the potential to greatly alter the diversity and abundance of Canada's native fishes, particularly in the Arctic, where its impact will be greatest.


The results of this status assessment clearly show that our knowledge of Canada's freshwater fishes far exceeds our knowledge of Canada's marine fishes, due to the difficulties of monitoring fish populations at sea, particularly in the Arctic Ocean. This makes it difficult to draw conclusions about the overall status of marine fishes. Hopefully this status assessment will raise awareness of the need to conduct more research on Arctic marine fishes, as this area may be strongly affected by climate change.

The updated freshwater fishes ranks suggest that the status of freshwater fish has not changed markedly since 2000, although the proportion of fishes ranked Secure has increased slightly. It should be noted that most of the changes were due to procedural changes and new COSEWIC status assessments.

Further information

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Bond, C. E. 1979. Biology of fishes. W. B. Saunders Co., Philadelphia. 514 pp Cannings, S. G. and Ptolemy, J. 1998. Rare freshwater fish of British Columbia. BC Environment, Victoria. 214 pp

Coad, B. W. with Waszczuk, H. and Labignan, I. 1995. Encyclopedia of Canadian fishes. Canadian Museum of Nature, Ottawa and Canadian Sportfishing Productions, Waterdown, Ontario. 928 pp

Census of marine life. (Accessed December 15, 2005).

Centre for marine biodiversity. (Accessed December 12, 2005).

Collette, B. B. and Klein-MacPhee, G. (eds.) 2002. Bigelow and Schroeder's Fishes of the Gulf of Maine. 3rd ed. Smithsonian Institution Press, Washington, DC, 748 pp., illus.

Eakins, R. J. 2005. Ontario freshwater fishes life history database. Version 2.80. On-line database. (Accessed 15 December, 2005).

Fisheries and Oceans Canada. (Accessed October 18, 2005).

Fisheries and Oceans Canada. Can Arctic Char adapt to climate change? (Accessed February 3, 2006).

Fisheries and Oceans Canada. 2002. Inshore rockfish biology. (Accessed December 20, 2005).

Fisheries and Oceans Canada. Rockfish conservation strategy. (Accessed December 19, 2005).

Froese, R. and. Pauly, D. Editors. 2006. FishBase, version (02/2006). (Accessed April 4, 2006).

Hart, J. L. 1973. Pacific fishes of Canada. Fisheries Research Board of Canada. Ottawa. 740 pp

Hart, P. J. B., and Reynolds, J. D. 2002. Handbook of fish biology and fisheries: Volume 1, Fish biology. Blackwell Science, 413 pp.

Helfman, G. S., Collette, B. B. and Facey, D. E. 1997. The diversity of fishes. Blackwell Science, 528 pp.

Herbert, P. 2002. Canada's aquatic environments. CyberNatural software. University of Guelph. (Accessed 15 December, 2005).

Inland fishes of New Brunswick: (Accessed April 3, 2006)

Integrated Taxonomic Information System (ITIS). (Accessed April 3, 2006).

Mandrak, N. E. and Crossman, E. J. 1992. A checklist of Ontario freshwater fishes: annotated with distribution maps. Royal Ontario Museum, Toronto. 176 pp

Marine Species Registers for the North Atlantic Ocean. (Accessed April 3, 2006)

MarineBio.org. (Accessed December 14, 2005).

Matthews, W. J. 1998. Patterns in freshwater fish ecology. Chapman and Hall, New York. 756 pp

McPhail, J.D., and C.C. Lindsey. 1970. Freshwater fishes of Northwestern Canada and Alaska. Fish. Res. Board Canada. Bulletin 173:381 pp.

Moyle, P. B. and Cech Jr., J. J. 2000. Fishes: and introduction to ichthyology, 4th ed. Prentice Hall, NJ. 612 pp

Nelson, J. S. 2006. Fishes of the World. 4th ed. John Wiley & Sons, New York. (Accessed April 3, 2006).

Nelson, J. S., Crossman, E. J., Espinosa-Pérez, H., Findley, L. T., Gilbert, C. R., Lea, R. N. and Williams J. D. 2004. Common and scientific names of fishes from the United States, Canada, and Mexico. American Fisheries Society, Special Publication 29, Bethesda, Maryland.

Nelson, J. S. and Paetz, M. J. 1992. The fishes of Alberta, 2nd ed. University of Alberta Press, Edmonton; University of Calgary Press, Calgary. 437 pp

Oceans and the Law of the Sea. Division for Ocean Affairs and the Law of the Sea, Office of Legal Affairs, United Nations. (Accessed October 20, 2005).

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Robins, R. C., Ray, C. and Douglass, J. 1986. Atlantic Coast fishes. New York: Houghton Mifflin Company. 354 pp

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Scott, W. B. and Crossman, E. J. 1973. Freshwater fishes of Canada. Bull. Fish. Res. Board Can. 184. 966 pp

Scott, W.B. and M.G. Scott. 1988. Atlantic Fishes of Canada. Can. Bull. Fish. Aquat. Sci. 219: 731

Sebastes.org. (Accessed December 21, 2005). Sierra Club of Canada - BC Chapter. State of the Strait backgrounder. (Accessed December 18, 2005).

Stewart, K. and Watkinson, D. 2004. The freshwater fishes of Manitoba. University of Manitoba Press. 276 pp

Wootton, R. J. 1990. Ecology of teleost fishes. Chapman and Hall, London. 404 pp


Barber, K. Ed. 1998. The Canadian Oxford dictionary. Oxford University Press. Toronto, Oxford, New York. 1707 pp

Coad, B. W. and Reist, J. D. 2004. Annotated list of the Arctic marine fishes of Canada. Can. MS Rep. Fish. Aquat. Sci. 2674: iv + 112 p

COSEWIC 2002. COSEWIC assessment and status report on the Bocaccio Sebastes paucispinis in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 43 pp

Fisheries and Oceans Canada - Pacific region. Canada's Ocean Act. (Accessed October 20, 2005).

Shelton, P. A., Sinclair, A. F., Chouinard, G. A., Mohn, R., and Duplisea, D. E. 2006. Fishing under low productivity conditions is further delaying recovery of Northwest Atlantic cod (Gadus morhua). Canadian Journal of Fisheries and Aquatic Science 63: 235-238

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