Key to shark ID

There are several useful field guides to shark identification. Some of these guides include The Sharks of North American Waters by José Castro and Sharks and Rays by Tricas, Deacon, Last, McCosker, Walker, and Taylor. Here we present an identification key to sharks found in waters around Atlantic Canada as outlined by Scott and Scott in their book Atlantic Fishes of Canada. Follow the question guide, click on the correct answer and use the diagram to help you with terms. With this key you can readily identify any of the 19 species of sharks that occur in the waters of Atlantic Canada.

Below there is a series of links. Click the ones that correspond to the shark you have seen to determine its identity.

Use this picture to help you answer the questions below.

Anal Fin Present

Head greatly expanded laterally; eyes locates at the lateral extremities (Smooth Hammerhead (Sphyrna zygaena))

Head not greatly expanded or enlarged laterally; body fusiform and typically shark-like

Dorsal lobe of caudal fin greatly enlarged, as long as head and body combined (Thresher Shark (Alopias vulpinas))

Dorsal lobe of caudal fin nearly equal in size to lower lobe, or only 2 or 3 times larger

Gill slits or openings greatly enlarged, the first pair nearly meeting over the throat, and all 5 seeming to almost sever the head; teeth minute and numerous; well developed lateral keels on caudal peduncle (Basking Shark (Cetorhinus maximus))

Gill slits of moderate size, not extending around the body; teeth not minute but well developed.

Origin of first dorsal fin distinctly posterior to origin of pelvic fins (Deepsea Cat Shark (Apristurus profundorum))

Origin of first dorsal fin anterior to origin of pelvic fins

Teeth smooth and pavement-like; 2 dorsal fins, the second almost as large as the first; origin of first dorsal overlapping posterior quarter of pectoral fin; spiracle below and behind posterior corner of eye (Smooth Dogfish (Mustelus canis))

Teeth sharp and pointed; 2 dorsal fins, the first larger than the second, the second sometimes very small

First dorsal fin only slightly larger than the second and distinctly behind pectoral fins, free edge of first dorsal overlapping origin of pectoral fins (Sand Tiger Shark (Odontaspis taurus))

First dorsal fin obviously larger than the second

Caudal peduncle and caudal fin with one or more distinct lateral or horizontal keels

A second smaller lateral keel below the primary keel, on lower lobe of caudal fin; teeth in adults with lateral cusps, one on each side of main cusp, these lateral cusps are not obvious in young Porbeagle (Lamna nasus)

No secondary keel below primary keel; teeth without lateral cusps

Cockscomb-shaped curved teeth with heavy serrations and notches in lateral margins, alike in both upper and lower jaws, distinctive mottled or striped pattern on body (Tiger Shark (Galeocerdo cuvier))

Triangular serrated teeth or pointed blade-like teeth, without mottled or striped pattern on body

Teeth slender and awl-like, the anterior teeth long and re-curved; origin of dorsal fin wholly posterior to pectoral fin base (Shortfin Mako Shark (Isurus oxyrinchus))

Teeth broad and triangular, the margins strongly serrated, alike in both jaws providing straight cutting edges, origin of dorsal fin slightly overlapping posterior portion of pectoral fin (White Shark (Carcharodon carcharias))

Caudal peduncle without distinct lateral keel

Teeth in upper and lower jaws without conspicuous serrations, margins entire; anal fin origin distinctly anterior to origin of second dorsal fin (Atlantic Sharpnose Shark (Rhizoprionodon terraenovae))

Teeth in upper and lower jaws with conspicuous serrations; second dorsal fin origin over or slightly in advance of anal fin origin

First dorsal fin set far back, nearer pelvic fins than pectoral fins; pectoral fins long, about three times as long as broad; no prominent ridge on dorsal surface between dorsal fins; upper parts of body brilliant blue in colour (Blue Shark (Prionace glauca))

First dorsal fin nearer pectoral fins than pelvic fins, its origins overlapping posterior margin of pectoral fin; length of pectoral fins moderate, less than three times as long as broad; a dorsal ridge present between the 2 dorsal fins

Dorsal fin apex broadly rounded ; posterior tip of anal fin long, reaching nearly to lower precaudal pit; posterior margin of lower caudal lobe with convex outline; tips of dorsal, pectoral, and caudal fins often white (Oceanic Whitetip Shark (Carcharhinus longimanus))

Tip of dorsal fin pointed, posterior end of anal fin relatively short, and far from reaching the dimple precaudal inferior crest well developed between the dorsal (Dusky shark (Carcharinus obscurus))

Anal Fin Absent

Dorsal fins without conspicuous spines at origin (Greenland Shark (Somniosus microcephalus))

Dorsal fins each with a spine at the origin, spine sometimes concealed by skin

Teeth in upper and lower jaw alike

Upper and lower teeth quadrangular, one cusp directed laterally to form an almost continuous cutting edge; dorsal fin spines rounded; trailing edge of upper caudal lobe entire; colour of body usually gray with light spots; length to about 90 cm (Spiny Dogfish (Squalus acanthias))

Upper and lower teeth each with 3 to 5 triangular cusps; dorsal fin spines deeply grooved; trailing edge of upper caudal lobe notched; colour uniformly dark brown to black; 60 to90 cm in length (Black Dogfish (Centroscyllium fabricii))

Teeth in upper and lower jaws not alike

Teeth in upper jaw with only one cusp; dorsal fin spines concealed by skin; body covered with flat overlapping denticles (Portuguese Shark (Centroscymnus coelolepis))

Teeth in upper jaw with 5 erect cusps; dorsal fin spines conspicuous; body covered with distinct skin spines (Rough Sagre (Etmopterus princeps))