rdsFishes of Canada's National Capital Region
Species Accounts
Cottidae - Sculpins - Chabots
Sculpins and bullheads are found principally in marine and fresh waters of the northern hemisphere. There are about 300 species with 63 in Canada but only 1 species in the NCR. A fossil, Myoxocephalus thompsonii (Girard, 1851)(regarded by some authors as a synonym or subspecies of M. quadricornis (Linnaeus, 1758), is recorded for the NCR in a clay nodule from Green Creek (Champagne et al., 1979; McAllister et al., 1987) but extant populations have not been recorded.
Sculpins have a naked body or have scales, plates, prickles or spines. The head is large and is blunt. It often has spines or knobs particularly 1-4 preopercle spines and the body tapers posteriorly. There is a large, dorsally placed eye. The mouth is large but teeth are generally small. There is 1 lateral line. The dorsal fin usually has separate, short spinous and longer soft portions. Pelvic fins (rarely none) have 1 spine (often embedded and hard to detect) and 2-5 soft rays. There are no anal fin spines. The pectoral fin is large and fan-shaped. The caudal is usually rounded or truncate. The hyomandibular bone has a unique lateral process. Adults lack a swimbladder. The males of some species have a penis-like urogenital papilla to deliver sperm internally to females. Eggs are few, large and demersal and may be guarded by the male. Coloration is usually mottled and drab.
Most sculpins are small, shallow water, bottom-living species abundant in tidepools and streams although some are found down to 2000 m. Food is bottom invertebrates such as molluscs, crustaceans, worms, insects and small fishes.
Bergeron and Brousseau (1982) and Bernatchez and Giroux (2000) map Cottus cognatus Richardson, 1836 from the general area of the NCR but this is not confirmed by specimens. Myoxocephalus thompsonii (Girard, 1851) and Cottus ricei (Nelson, 1876) are found in waters just outside the NCR, in Lake Heney, Québec for example. Some literature and museum specimen records of Cottus ricei need verification.
Mottled Sculpin / Chabot tacheté
Cottus bairdii Girard, 1850
Taxonomy
Other common names include Miller's Thumb, Columbia Sculpin, Muffle-jaw, Spoonhead, Blob, Gudgeon, Freshwater Sculpin, Muddler, Springfish and Lake Sculpin. The subspecies in the NCR is probably C. b. kumlieni (Hoy in Nelson, 1876), the Great Lakes Mottled Sculpin.
Key Characters
This is the only sculpin in the NCR. It has the typical sculpin shape with 3 preopercular spines and 4 pelvic fin rays.
Description
This species has 2 pores on the tip of the chin. There is an incomplete lateral line. Prickles are found only behind the pectoral fins. There are palatine teeth in the roof of the mouth. The last 2 dorsal and anal rays close together and the fourth pelvic fin ray is about three-quarters as long as the longest ray. Usually there are 14-16 (range 12-17) pectoral rays. Caudal peduncle length is less than postorbital length. First dorsal fin spines 6-9, second dorsal rays 15-19 and anal rays 10-16. There are 15-36 lateral line pores. Males have a thin, elongate genital papilla.
Colour
Overall colour light to dark brown or olive with back and sides darkly mottled. The belly is white. There are 2-3 saddles at the second dorsal fin and 2 fainter saddles at the first dorsal fin. There is a dark bar at the base of the caudal fin. Fins are thinly barred brown or dusky. The first dorsal fin has an anterior and a posterior spot. The chin has some speckling. The breeding male develops a dark stripe on the first dorsal fin with a broad orange stripe above it to the edge of the fin. Male overall colouration is darker than the female, being blue-black.
Size
Reaches 17.7 cm.
Distribution
Found in the Columbia and Milk River drainages of southern British Columbia and Alberta, and in adjacent U.S. states. This distribution is separated from an eastern one stretching from northeastern Labrador, Ungava, western Québec, Ontario and the Great Lakes, to southern Manitoba. In the U.S. it is found south to Georgia and Alabama.
Origin
This species entered the NCR from possibly an Atlantic coastal or Mississippian refugium (Mandrak and Crossman, 1992).
Habitat
This sculpin favours cool streams and lakes over sand or gravel bottoms. They will burrow in the bottom if approached. Depth range is from the shallows down to about 16 m and preferred temperature is 16.6°C.
Age and Growth
Maturity is reached at age 2-3 years and life span is 6 years.
Food
Food is mainly aquatic insects with some crustaceans, worms, rarely macrophytes and small fishes, and fish eggs. However they are not a major predator on eggs of trout and other sport species. Mottled Sculpins feed in the open at night and hide among rocks during the day. Food includes both swimming prey and prey buried in the substrate. The latter can be located by detecting prey movement using the mandible or large lower jaw bone. The sculpin places its lower jaw on the bottom to detect prey vibrations, "hops" towards the stimulus and bites into the sand. The mandible has very large neuromasts which aid in reception of the signal. This ability to detect vibrations may also be used to locate potential predators and in communication among members of a species. They are eaten by Brook Trout and water snakes.
Reproduction
Spawning takes place in spring, mainly in May in Canada at 5-16°C. An eyed egg mass was found in Sawmill Creek, Ottawa on 25 May at a water temperature of 11°C (McAllister and Coad, 1975). Males defend a nest under a rock, and entice females there by a courtship display which involves head shaking and nodding, expanding the gill cover and undulating the body. Knocking sounds are produced by head nods and slaps to the substrate, and drum rolls are produced by a rapid series of knocks followed by a head slap. Spawning takes place at night so sound is very important as a signal in nest defense and possible female choice of males. The male will also bite the female or take her head into his mouth and shake her. Females select larger males to mate with as these have a higher breeding success and favour those with nests under larger rocks. They spend about a week searching for a large male as too long a delay in selection leads to high egg mass failures because of late egg laying. However too large a male will eat the female. Eggs are deposited on the roof of the nest, the female is driven away and the male guards and fans the eggs. Up to 12 females may breed with 1 male but females breed only once per season. Large males succeed in hatching more eggs than small males. Each female may produce up to 635 eggs of up to 3.0 mm diameter and a nest can contain up to 2874 eggs.
Importance
Occasionally caught by anglers and, if they are unfamiliar with sculpins, occasions much surprise from its "ugly" appearance. It may be an important food for Brook Trout in streams.
© Brian W. Coad (www.briancoad.com)