Species Accounts
Osmeridae - Smelts - Éperlans
Smelts are found in coastal sea waters and freshwaters near the coast of the Northern Hemisphere. Some populations are land-locked. There are about 11 species with 9 reported from Canada and 2 from the NCR.
These small, silvery fishes have a single dorsal fin at mid-body, an adipose fin, no pelvic axillary process (found in related Salmon Family members), 8 pelvic fin rays and 19 principal caudal fin rays, forked tail, 6-10 branchiostegal rays, 0-11 pyloric caeca, a stomach sometimes with a blind sac, the last vertebra at the tail is turned up, teeth are on numerous mouth bones and are strong or weak, a mesocoracoid bone is present in the pectoral fin skeleton and the skull lacks the orbitosphenoid bone. Scales are cycloid and easily detached. Some smelts have a strong cucumber smell when fresh, the chemical being trans-2-cis-6-nonadienal. Its function is unknown.
Breeding smelts can develop tubercles, modified scales and enlarged fins. Reproduction may occur in coastal waters or involve a migration into freshwater. Smelts are all carnivorous fishes. They are very numerous and so are important food fishes for commercially important species and are also used as bait by anglers. They are rich in oil and are excellent smoked for human consumption.
Fossils of Mallotus villosus (Müller 1776), another smelt species, are very common in nodules from Champlain Sea deposits throughout the NCR (Arsenault, 1979; McAllister et al., 1987).
Rainbow Smelt / Éperlan arc-en-ciel
Osmerus mordax (Mitchill, 1814)
Taxonomy
Other common names include American Smelt, Atlantic Smelt, Atlantic Rainbow Smelt, Arctic Rainbow Smelt, Freshwater Smelt, Saltwater Smelt, Frostfish, Icefish, Leefish, Lake Smelt, Spirling, Sea Smelt, Éperlan du nord and Éperlan d'Amérique.
Key Characters
This species is distinguished by the presence of an adipose fin but it lacks the pelvic axillary scale found in the Salmon Family which it resembles. It is separated from the only other smelt in the NCR by usually having up to at least 200 mm standard length, having 8-14 upper arch and 15-24 lower arch gill rakers (usually 28-32 total), and orbit diameter 7.0-11.3% of standard length.
Description
Dorsal fin rays 8-11, anal rays 11-17 and pectoral rays 9-14. Lateral line scales 56-72 with 13-30 pored. Total gill rakers 26-37. There are medium conical to large canine teeth on the tongue, 4-9 pyloric caeca, and 1-3 large canines on each side of the vomer bone in the roof of the mouth. Males have numerous head, body and fin tubercles. The mouth is large and reaches the rear of the eye. Paired and anal fins are larger in males and a lateral ridge may develop. The right ovary and right testis in this species are significantly smaller than the left (Legault and Delisle, 1968).
Colour
The back is olive-green, steel blue or black and the flank is silvery with purple, blue or pinkish iridescences (hence "rainbow"). Scales on the back are outlined with pigment. There is a silvery stripe along the flank which turns dark in preserved fish. The peritoneum is silvery with dark pigment dots. Landlocked smelt are darker than other populations and may have dusky fins rather than the typical clear fins. Faber (1985a) illustrates a larva.
Size
Reaches 35.6 cm.
Distribution
Found from southern Labrador throughout the Maritimes south to New Jersey in the sea. Also enters rivers and is landlocked in lakes throughout eastern Canada. Introduced and widespread in all the Great Lakes and adjacent inland lakes including Lake Winnipeg (also introduced in the Mississippi River basin). In the Arctic from Cape Bathurst, N.W.T. coastwise around Alaska and south to Vancouver Island but relatively rare in Pacific Canada.
Origin
Anadromous smelt require summer sea temperatures above 10°C and this would prevent invasion of the Champlain Sea until about 11,000 B.P At this time sea level in the NCR had fallen to a present-day level of 450 ft and so smelt could only enter lakes in the central Gatineau Valley. Lakes in the southern Gatineau Valley above 450 ft were inaccessible (Dadswell, 1974).
Fossils of Quaternary age (ca. 10,000 years ago) have been found in clay nodules from Green Creek in the NCR (McAllister et al., 1981; Harington, 1972; 1983; McAllister et al., 1987).
Habitat
Rainbow smelt are found as landlocked populations in numerous lakes of various sizes, although deep and thermally stratified in summer. In lakes cool water is preferred, about 7°C, although some reports give 15°C as the preferred temperature for the species. They are not attracted to lights at night nor does they make vertical migrations in Heney Lake in contrast to Pygmy Smelt (Delisle, 1969a). They are pelagic with a maximum recorded depth of at least 150 m in the sea. In the Great Lakes they are commonest at 18-60 m and rarely descend below 75 m. They also occur in rivers. This smelt is susceptible to acute infections with Glugea hertwigi, a sporozoan parasite, in the NCR. White cysts of the parasite cause the intestines to adhere together and the fish starve (Delisle, 1965a; 1965b; 1969; Legault and Delisle, 1967; Delisle et Veilleux, 1969).
Age and Growth
Females live longer, grow faster and are larger than males. Life span is 5-9 years in most populations but up to 17 years on the Beaufort Sea coast of the Yukon. Maturity is attained at age 3 in Atlantic populations although some fish mature a year earlier. Alaskan and northern Canadian populations mostly mature at ages 4-7, often at 6-7 years and 20-22 cm. In Heney Lake most fish reach maturity at 3 years with a maximum life span of 6+ years (Delisle, 1969a).
Food
Food is often opossum shrimps and other invertebrates such as worms and insects in fresh waters. Over 50% of the diet in Heney Lake is adult Pygmy and young Pygmy and Rainbow smelts (Delisle, 1969a). Many fishes in lakes depend on smelt as a food source including such economically important species as Atlantic Salmon, Brook Trout, Lake Trout, Walleye and Yellow Perch.
Reproduction
Spawning migrations take place February to June, being later in northern seas and lakes. The run usually starts when water temperatures reach 4°C or higher, just after the ice breaks up and moves out. Lake populations enter rivers even under ice. Spawning itself takes place at 5-9°C in various localities in Ontario. Spawning in Meech Lake, Québec was observed on 19 May (Bridges and Delisle, 1974) but these may be Pygmy Smelt. Deepwater spawning takes place in Lake Heney, north of the NCR. Temperatures here are below 4°C in March-April (Legault and Delisle, 1968; Delisle, 1969a; Lanteigne and McAllister, 1983). Thellen (1994) gives a range of 8.9-18.3°C for fish in the Outaouais generally. Males are first on the spawning grounds in freshwater areas of rivers. Spawning occurs at night. Eggs are adhesive, 1.0 mm in diameter, and number up to 93,000 per female. The outer membrane of the egg ruptures but remains attached to the egg by a stalk. This outer membrane is the adhesive part and the egg sways in the water at the end of the stalk. They become attached to vegetation or rocks and may be so numerous that some are smothered. As many as 190 eggs/sq cm have been counted. Larvae are 4.0-5.0 mm at hatching. The fry are carried downstream to the lake after hatching.
Importance
Mass mortalities of adults have been reported in the Great Lakes after spawning, 200 m long, 4.6 m wide and 0.3 m deep. This creates a health hazard, renders beaches unusable and is costly to clean up. Smelt are important in both sport and commercial fisheries. They can be legally seined or dip-netted at night on the spawning run, caught on hook and line from docks, or through the ice in winter. Commercial catches are taken in the Great Lakes using otter trawls and in the Miramichi River estuary by box nets through the ice. Bag nets, fyke nets, gill nets and seines are also used. In 1979 2542 tonnes worth $1,065,767 were caught in Atlantic coastal areas of Canada and 10,979 tonnes in the Great Lakes worth $2,035,000. Ontario had a catch of 7289 tonnes in 1966 and smelt occupied first place by weight among all Great Lakes fishes in that year. The total Canadian catch in 1988 was 11,000 tonnes worth about $4.2 million. Smelt are sold fresh, frozen or pre-cooked, are delicious fried and are in high demand by consumers in Japan and the U.S.A. Their cucumber-like odour when fresh is distinctive and probably accounts for the name "smelt". Fishermen have claimed that smelt are important predators on commercially important species. Although fish are a relatively small part of the smelt diet (as little as 4.3% for males in Lake Simcoe), the numbers of smelt alone lend some weight to this accusation. Whether the numbers of young commercial fishes eaten by smelt are offset by the numbers of smelt eaten by survivors remains to be determined. Rainbow smelt have been widely distributed in southern Ontario as bait fish introductions.
Pygmy Smelt / Éperlan nain
Osmerus spectrum Cope, 1870
Taxonomy
Recent studies maintain that the dwarf and large forms of smelt in lakes should be regarded as stocks rather than species (Lajoie, 1986; Bernatchez and Giroux, 2000). This form is retained here with a separate account for its local interest.
Key Characters
This smelt is distinguished from the other lake smelt in eastern North America, the Rainbow Smelt, by being less then 13.5 cm standard length, usually 34-36 (range 32-36) gill rakers and eye diameter 4.4-6.5% of standard length (Delisle et Veilleux, 1969; Copeman, 1973; 1977; Lanteigne and McAllister, 1983).
Description
In addition to the key characters above, mid-lateral scales number 58-66 and vertebrae 59-63.
Colour
Overall coloration silvery. Preserved fish have a dark flank stripe and speckled fins with the anal fin being almost clear.
Size
Attains 22.9cm (Cuerrier, 1983).
Distribution
Found in Heney Lake, Québec, Lake Utopia, N.B. and in lakes of southern Maine. Probably in various other Québec, N.B. and Maine lakes. Introduced to Meech (or Meach) and Ouimet lakes, Québec from Lake Utopia (Lanteigne and McAllister, 1983). Dymond (1939) records that the Meach Lake fish were introduced as half a million eggs in each of two successive years about 1924, a few specimens were subsequently reported but the species was then believed to be extinct. Records from the Ottawa River and Québec lakes (other than Meech) mapped here may well be mis-identifications.
Origin
Presumably from an Atlantic coastal refugium for those local stocks that are native.
Habitat
This smelt lives in lakes along with the larger Rainbow Smelt. The lakes are small, deep and thermally stratified in summer. Delisle (1969a) and Lanteigne and McAllister (1983) summarise biology in Heney Lake (= Lac Poisson Blanc) north of the NCR. The population size of 2-3 years olds there has been estimated at 22 million fish by Delisle but it may not have been as common by 1984 (McAllister et al., 1985). Adults migrate in July from the hypoliminion at the bottom (at 7-9°C) to the epiliminion (at 21°C) at 2300 to 0200 hours. Adults form schools beneath the ice in January. Young pygmy smelt are found in schools and are attracted to artificial lights at night. Young-of-the-year have been reported in shallow water in July, August and winter near sand and gravel beaches. They migrate from deep water to the surface between 0100 and 0400 hours in April before spawning. They are susceptible to the same sporozoan parasite as Rainbow Smelt with a massive spring-time mortality of at least 2-3 million fish (McAllister et al., 1985).
Age and Growth
Maturity is reached at age 2 and life span is 5+ years although only 2.2% reached this maximum in Heney Lake north of the NCR. Most spawners are 2 years old. Growth is slower in Pygmy Smelt than in Rainbow Smelt (Delisle, 1969a; Copeman, 1977).
Food
Food is mainly plankton such as adults and eggs of water fleas (Daphnia) and adult Cyclops and Bosmina in Lake Heney north of the NCR (Delisle, 1969a) but may also include insects and amphipods.
Reproduction
Spawning occurs in April and May during and after spring breakup, and later than Rainbow Smelt in Lake Heney, north of the NCR and in transplanted fish in Meech Lake in the NCR. Temperatures are 4-8°C (average 6°C) and eggs are shed on sand and gravel beaches (Delisle, 1969a; Bridges and Delisle, 1974). Up to 3774 eggs of 0.7 mm diameter are found in preserved females (Delisle, 1969a).
Importance
The Committee on the Status of Endangered Wildlife in Canada is considering a status of "rare" for this species. Numbers of Pygmy Smelt in Heney Lake appear to have declined. Millions of eyed eggs of this species taken from Meach Lake in Gatineau Park in May 1965 and May 1966 were introduced to Papin Lake in Pontiac County (76°06'N, 46°09'W) just outside the NCR as food for Ouananiche (introduced landlocked Atlantic Salmon)(Cuerrier, 1983).
© Brian W. Coad (www.briancoad.com)