Glauco-Puig-Santana_Allied-Whale

SHARKS

While as many as twenty species of shark are known to inhabit the western North Atlantic waters, little is known about their distribution, movements or occurrence. Even less is known about the threats they face.

Sharks are cartilaginous fish – skeleton made of cartilage, not bone – that are characterized by slow growth, late maturity, long life and low fecundity (i.e. the ability to reproduce). Sharks are very fragile animals when out of the water. If sharks strand, become entrapped or forced to stop swimming, they can suffocate. Action must be taken as quickly as possible after the discovery of a shark to increase the chances of survival.

A shark’s skin is made up of dermal denticles (tiny tooth-like scales) that cover the animal, making its skin feel rough to the touch. Sharks have five rigid fins which they can’t fold down against their bodies. Individual sharks (i.e. basking and white sharks) can be identified from photographs of their dorsal fins. This technique is called photo-identification and has been used to distinguish individuals of other species, such as humpback whales, right whales and sperm whales.

Most species of sharks have five pairs of gill slits on each side of their head, which are crucial to their breathing system. By opening their mouth, water is drawn into the shark. When it closes its mouth, the water is forced over its gills and the tiny blood vessels in shark gills absorb oxygen from the water. In order to aid in passing water over their gills most sharks must swim forward all the time, known as ram ventilation.

Illustration © Frédérique Lucas

Of the many species that occur in our waters, six are commonly sighted or encountered. Profiles of these species can be found below.

Canadian species’ conservation status is first assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), followed by a process to determine if the species will be listed under the Species at Risk Act (SARA).

BASKING SHARK

Cetorhinus maximus
Species at Risk Act Status Status: NO STATUS
COSEWIC Status: SPECIAL CONCERN

Length: 10 m / 32 ft

Illustration © Frédérique Lucas
Key Identification Features:
  • Greyish-brown often with mottled appearance
  • Large conical snout
  • First dorsal fin is rounded on top, set further back on body and at a 45° degree angle
  • Five massive gill slits that almost encircle the head

May be confused with a White Shark.

WHITE SHARK

Carcharodon carcharias
Species at Risk Act Status: ENDANGERED
COSEWIC Status: ENDANGERED

Length: 8 m / 26 ft

Illustration © Frédérique Lucas
Key Identification Features:
  • Lead grey, brownish grey or black
  • Large triangular-shaped first dorsal fin
  • Trailing edge of the first dorsal fin has unique markings or serrated edge
  • Large, triangular shaped teeth with serrated edge

May be confused with a Basking Shark.

COMMON THRESHER SHARK

Alopias vulpinus
Species at Risk Act Status: NO STATUS
COSEWIC Status: NO STATUS

Length: 6 m / 19 ft

Illustration © Frédérique Lucas
Key Identification Features:
  • Brown, grey, blue-grey or black colouration.
  • Extremely large upper lobe of the caudal fin (may be as long or longer than body length).
  • Short stubby snout.
  • Second dorsal fin is much smaller than the first dorsal fin.

SHORTFIN MAKO SHARK

Isurus oxyrinchus
Species at Risk Act Status: NO STATUS
COSEWIC Status: ENDANGERED

Length: 3.9 m / 13 ft

Illustration © Frédérique Lucas
Key Identification Features:
  • Metallic indigo blue colouration.
  • Distinct primary keel. ‘Keel’ is a ridge found on the narrow part of the shark to which the tail fin is attached – the tail stalk. Secondary keel is absent.
  • Moderately short pectoral fins.
  • Second dorsal fin is much smaller than the first dorsal; First dorsal is rounded in juveniles.

May be confused with a Porbeagle Shark.

PORBEAGLE SHARK

Lamna nasus
Species at Risk Act Status: NO STATUS
COSEWIC Status: ENDANGERED

Length: 2.5 m / 12 ft

Illustration © Frédérique Lucas
Key Identification Features:
  • Colouration is heavy grey-blue.
  • Distinctive white patch on the trailing edge of the first dorsal fin (see picture above).
  • Caudal fin has both primary and secondary keel. ‘Keel’ is a ridge found on the narrow part of the shark to which the tail fin is attached – the tail stalk.
  • Teeth are smooth and tricuspid (a point on either side).

May be confused with a Shortfin Mako.

BLUE SHARK

Prionace glauca
Species at Risk Act Status: NO STATUS
COSEWIC Status: NOT AT RISK

Length: 3.8 m / 13 ft

Key Identification Features:
  • Deep Indigo blue colouration.
  • Long slender body with long pectoral fins.
  • Distinct countershading; dark blue colour on top, bright blue on the sides and white underneath.
  • Nictitating membrane over its eye.

LEARN MORE ABOUT OTHER MARINE ANIMALS

Cetaceans

Pinnipeds

Sea Turtles

HELP US RESPOND TO DISTRESSED, STRANDED AND DEAD MARINE ANIMALS IN THE CANADIAN MARITIMES

Species information above taken from Shark Identification Network. To report your shark sightings, visit SIN.