Smooth dogfish

Mustelus canis

Description

The smooth dogfish has a slender body with an obvious spiracle behind the eye. The caudal fin has a rounded lower lobe and a larger top lobe. The teeth are very small, blunt, numerous and similar in both the upper and lower jaw. This shark is olive gray or brown on top and yellow or grayish white below. The smooth dogfish is able to change its colour slowly through contraction of melanophores (migratory pigment cells that through contraction or relaxation give the impression of a colour change). It is primarily nocturnal.

Range

This species of shark occurs in the western Atlantic Ocean. It ranges from the Bay of Fundy to Uruguay. It is a common shark in the waters off Cape Cod to Delaware Bay, and overwinters from Chesapeake Bay to South Carolina. It is rare in Canadian waters and the Bay of Fundy represents the northern most part of its range.

Habitat

This shark commonly lives in bays and inshore waters. It prefers waters less than 18 meters (60 feet) deep but has been found to a depth of 200 m.

Life History

This shark grows to 1.5 meters (5 feet) in length. Average size is about 122 cm (48 in). The smooth dogfish is a migratory species that moves north and south with the seasons.

Diet

This shark is a scavenger and opportunistic feeder, but regularly feeds upon crabs, lobster and shrimp as well as a variety of small teleosts.

Reproduction

The smooth dogfish is a viviparous shark giving birth to a litter of 3 to 18 pups. Gestation is 10-11 months long and the young are usually delivered in the late spring or early summer. The pups are 34 to 39 cm (13 to 15 in) at birth. Sexual maturity is reached when individuals reach 102 cm (40 in) for females age 4-5, 86 cm (33 in) in length for males age 2-3.

Interaction with People

This shark is very common, similar to the spiny dogfish, and routinely fowls up fishing gear. It is frequently caught by shrimp trawlers. It is considered harmless and is often used in aquaria.

Distinguishing Characteristics

• Can change colour
• No dorsal fin spines
• Prominent spiracle behind eye
• Numerous small blunt teeth in both jaws