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Blue
Shark
The blue shark is one of the most easily recognized sharks. It has a distinct colouration, a deep indigo blue from above and a vibrant blue on its sides, changing to white underneath. The large pectoral fins are also easy to spot as they are as long as the distance between the tip of the snout to the last gill slit. The blue shark is a long slender shark, reaching 3.8 meters (13 feet) in length. It is likely the most prolific of the large shark species as it is abundant throughout its range. The blue shark has a weak keel on the caudal peduncle and the upper lobe of the caudal fin is larger than the lower. The teeth on both the lower and upper jaw have triangular cusps with smooth or finely serrated edges.
Diet The diet of this shark includes many types of fish and squid, and may sometimes eat seals. Although flatfishes make up part of the diet, blue sharks predominantly eat pelagic fishes such as herring, silver hake, white hake, red hake, cod, haddock, pollock, mackerel, butterfish , sea raven, tuna and swordfish. Fish caught on longlines during fishing are often attacked and consumed by blue sharks, who in turn often become ensnared in the fishing gear. Reproduction The blue shark is a viviparous species, nourishing the young in the uterus and giving birth to live pups. The new-born pups measure 40 to 51 cm (16 to 20 inches) in length and litters usually consist of between 25 to 50 individuals. Litters of up to 135 pups have been reported. Females reach sexual maturity at a size of 2.2 to 3.2 meters (7 to 11 feet), while for males it is achieved at lengths of 1.8 to 2.8 meters (6 to 9 feet). After copulation the females may retain and nourish the spermatozoa in the oviducal gland for months or even years while she awaits ovulation. Once the eggs have been fertilized there is a gestation period of between 9 and 12 months. Habitat In temperate waters the blue shark is a wide ranging pelagic species occurring near the surface. In tropical waters the blue shark is more commonly found in deeper waters as it prefers temperatures between 7 and 16 degrees Celsius. Range The blue shark occurs in the Atlantic, Pacific and Indian Oceans in both inshore and offshore waters. This wide ranging species is found from 50º N latitude to 50ºS latitude. In the western Atlantic it can be found from Newfoundland and the Gulf of St. Lawrence to Argentina. In Canadian waters the blue shark has been found in southeastern Newfoundland, the Grand Banks, the Gulf of St. Lawrence, the Scotian Shelf and the Bay of Fundy.
Distinguishing Characteristics
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