Fishes of Canada's National Capital Region
Species Accounts
Gadidae - Cods - Morues
Cods are mostly northern marine fishes with 1 species in freshwater of North American and Eurasia and a few southern hemisphere species. There are about 30 species and in Canada 24 species with 1 in the NCR.
Cods have a first dorsal fin behind the head and 1-3 distinct dorsal fins. There are 1-2 anal fins. There are no fin spines. The caudal fin usually extends around the dorsal and ventral tip of the caudal peduncle often framing a pointed end to the body. The vomer bone in the roof of the mouth bears teeth. The swim bladder is not connected to the auditory capsules and has 2 slender, anterior processes. There is usually a barbel at the tip of the lower jaw. Scales are small and cycloid. There is an obvious lateral line.
Most cods live on or near the bottom in cold shelf and slope waters of the sea in large schools and are of immense commercial importance as food and sport fishes. Eggs and larvae are usually pelagic. Egg production can exceed 60 million in some species. Adults feed on other fishes and various invertebrates. Cods are the principal food fish consumed by humans.
A fossil of a freshwater to marine species, Microgadus tomcod (Walbaum, 1792) has been found in peri-Champlain Sea nodules at Hiawatha Park on the Ottawa River and from Covent Glen, Ottawa and and the mostly marine species Gadus morhua Linnaeus, 1758 has been found at Eardley (McAllister et al., 1981; 1987).
Burbot / Lotte
Lota lota (Linnaeus, 1758)
Taxonomy
Other common names include Ling, Sand Ling, Eelpout, American Burbot, Freshwater Cod, Mother-of-Eels, Gudgeon, Maria, Methy, Freshwater Cusk, Spineless Cat, Dogfish, Lawyer, Lush, Loche, Queue d'anguille, Freshwater Eel, Lotte de rivière, Titaliq, Nätarrnaq, Tiktabek, Shulukpaoluk, Nettârnak. The name lawyer is said to be in allusion to its slipperiness or to its aggressive behaviour and voracious feeding. The word "burbot" is derived from the Middle French "bourbotte" from the verb bourbeter, to wallow in mud.
Key Characters
This is the only freshwater member of the Cod Family and its shape is distinctive. It has 2 dorsal fins, 1 anal fin, pelvic fins anterior to the pectorals and a single barbel at the chin tip.
Description
There are large, tubular nostrils. The dorsal and anal fins are fleshy and rays cannot be counted without dissection. First dorsal fin rays 7-16, second dorsal rays 60-94. Anal fin rays 52-86, pectoral rays 15-24 and pelvic rays 5-9. The embedded scales are very small. Pyloric caeca 31-168.
Colour
Overall colour varies from yellow-brown to brown or dark olive with black mottling and blotching. The belly is yellowish-white. Some fish may be uniform brown, purplish-black or black. The pelvic fins are pale and other fins are dark and mottled. The second dorsal, caudal and anal fins have a dark, submarginal band while the margin is bright yellow or orange. Young fish are usually dark and can have a white anal fin with a black edge and black rays in the pectoral fin. Faber (1985a) illustrates the larva.
Size
Reaches over 1.22 m and 34 kg. The world, all-tackle, angling record weighed 11.23 kg and came from Lake Louise, Alaska in 1976. A 10.2 kg fish was caught in Little Athapapuskow Lake, Manitoba.
Distribution
Found throughout Canada except coastal British Columbia, extreme northeastern N.W.T., the Arctic Islands, the outer coast of Québec and Labrador, Nova Scotia, P.E.I. and Newfoundland. Also in the northern U.S.A. and across all of northern Europe.
Origin
This species entered the NCR from a Mississippian or possibly an Atlantic coastal refugium (McAllister and Coad, 1975) or possibly a Beringian refugium (Mandrak and Crossman, 1992).
Habitat
Burbot are found in lakes down to 214 m and in large, cool rivers, generally preferring water colder than 18°C (other reports give a preferred temperature of 13°C or below and even 21.2°C). A preferred habitat is under rocks, among roots or in holes in banks. In large lakes, trenches are excavated for a habitat. In rivers turbid water is preferred. Generally they are sedentary. They may move into shallow water at night in summer and there may be long-distance spawning migrations. Young Burbot can be common in lake shallows and streams. In the NCR, they are most commonly caught in rivers and streams. In the Mississippi River, one specimen was caught among rocks in turbulent water flow.
Age and Growth
Females are larger than males and often mature later. Maturity is usually attained at 3-4 years and life span is up to 20 years. Not all adults spawn each year. In Lake Simcoe, Ontario males mature at 34.3 cm and 255 g and females at 41.9 cm and 680 g, both at age 3.
Food
Food, taken at night, is aquatic insects, crayfish, molluscs and other invertebrates when young (up to 50 cm) but older burbot eat mostly fishes with some opossum shrimps and other crustaceans, the latter especially in winter. Young-of-the-year Burbot in the Ottawa River at Kettle Island and Upper Duck River fed predominately on amphipods and darters but also took isopods, worms, snails, fly larvae and dragonfly larvae (Hanson and Qadri, 1980b). The Burbot is a competitor with many fishes for food, especially since it feeds indiscriminately and voraciously on whatever is available. The barbel and the pelvic fins are used to taste food before ingestion, even ejecting a food item from the mouth and passing it back to the pelvics several times before finally consuming it. Young Burbot are eaten by various other fishes.
Reproduction
Spawning takes place from January to March under ice during a short 2-3 week spawning season. There is a movement into shallow water for spawning, usually at depths less than 3 m, over sand, gravel or cobbles near the shore or on shoals in lakes, and in main channel rivers and streams where velocity is low. Males arrive first on the spawning grounds followed in 3-4 days by females. Water temperatures are 0.6-1.7°C. Up to 12 fish form a moving, wriggling ball over the bottom at night. Eggs are shed into the water column above the substrate, fertilised and left unattended. Eggs are up to 1.9 mm in diameter and number as many as 1,362,077, perhaps up to 3.5 million. They are semipelagic but gradually sink until lodging in gaps between sand and gravel. They take up to 18 weeks to hatch at temperatures below 2°C. Larvae are 3.0-4.0 mm long and live in open water.
Importance
Burbot have been used for fish meal, oil and food for animals raised for fur. It has white, flaky flesh and is good eating but has not found general acceptance as a food fish. It is said to taste like "barbotte" (Ameirus nebulosus), a more familiar food species in the NCR. Smoked Burbot livers are a delicacy in Europe. Anglers often catch Burbot when ice fishing for Lake Trout or other species. Sarsfield (1975a) records a 5½ lb "ling" caught in the Annual Ice Fishing Derby at Britannia Park. Burbot can be a nuisance to commercial fisheries, eating other commercial fishes caught in gillnets or clogging gillnets and wasting time in removing them. A report in 1903 attributed the loss of pike, bass and perch from night lines set in the Mississippi River of the NCR to "ling", only the heads of the fishes remaining on the hooks (Brown, 1984). It is reputed to eat the eggs of more commercially valuable fishes (Prince and Halkett, 1906).
© Brian W. Coad (www.briancoad.com)