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Marine SpeciesFrom Lower North Shore
[edit] Marine Species The Lower North Shore[edit] The Beluga WhaleThe Beluga is a pure white, toothed whale with a prominent, rounded forehead. Its thick skin and lack of dorsal fin are believed to be adaptations to cold, icy waters. It is a medium sized whale. The females average 3.5 m in length, while males average 3.6 m, sometimes exceeding 4 m. Newborns are brown or slate-grey and average 1.6 m in length, they become bluish-grey as they mature, then progressively lighten in colour, fading to white after 6 years of age. The population of Belugas seen along the Lower North Shore comes from the population which occurs mainly in the St. Lawrence River and in the Gulf of St. Lawrence. Belugas in general occur only in seasonally ice-covered parts of Arctic and sub-Arctic seas. The St. Lawrence Beluga's distribution represents the southern limit of the species' worldwide range.
Potential limiting factors include habitat alteration by dams on rivers draining into the St. Lawrence River; finite food sources; and competition for food from other species. Several pollutants have been discharged into the St. Lawrence and Saguenay rivers and their tributaries, as a result of increased industrialization, agricultural development and urbanization. These pollutants have had a direct impact on the health of the St. Lawrence Beluga population.
[edit] Blue WhaleThe blue whale is the largest animal known to have ever existed on the planet. The biggest Blue Whale ever recorded was 29.5 m long. Blue Whales are baleen whales which means that they are filter feeders. They use baleen plates to filter out their food from the water. They have between 60 and 88 throat grooves running from the throat to mid-body; those allow the throat to expand during the intake of huge amounts of water during feeding. Their tapered, elongated bodies are widest at the level of the eye, with the head accounting for about one-quarter of the total length. Overall, Blue Whales coloration is a blend of dark and light shades of grey. The pattern on their chevron can vary considerably among the species, but it is unique to each individual, and remains stable over time. It can therefore be used to identify individuals and track their movements and behaviour through photo-identification. Blue Whales are found in all the oceans of the world. During spring, summer, and fall, these whales occur along the north shore of the Gulf of St. Lawrence and off eastern Nova Scotia. In summer they also occur off the south coast of the island of Newfoundland and in the Davis Strait, between Baffin Island and Greenland. They usually migrate south for the winter, but in years of light ice cover, some whales may remain in the St. Lawrence for much of the winter. We do not know how many Blue Whales there are in the Atlantic population, but between 20 and 105 Blue Whales are seen annually in the Gulf of St. Lawrence. Blue Whales migrate in small herds, spending the summer in food-rich areas close to the edge of the polar ice, and the winter in temperate waters. They feed almost exclusively on krill and one whale may eat as much as 4 tons per day. Blue Whales generally dive on average for 5 to 15 minutes. and rare dives of up to 36 minutes have been recorded in the St. Lawrence. Male and female Blue Whales reach sexual maturity at between 5 and 15 years of age, females when they measure from 21 to 23 m long and males at a length of 20 to 21 m. Mating and the birth of young take place during the fall and winter in the warmer southern waters. Females give birth, usually to a single calf, every two or three years after a gestation period of 10 to 11 months. It has been estimated that Blue Whales live from 70 to 80 years. They can swim at speeds of up to 36 km/hr, but typically cruise at 2 to 8 km/hr when they are feeding or travelling. Past commercial whaling of Blue Whales is the main factor responsible for the decline in the animals' population. At least 11 000 Blue Whales were harvested in the North Atlantic before 1960. Approximately 1500 of these were harvested in eastern Canadian waters from 1898 to 1951. Since the end of commercial whaling, human threats have included collisions with ships, disturbance from increasing whale-watching activity, entanglement in fishing gear, and pollution (especially oil pollution). The Blue Whale Atlantic population is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
[edit] Fin WhaleThe fin whale is second only to the blue whale in size and weight. Adult males measure up to 78 feet (24 m). Weight for both sexes is between 50-70 tons. Among the fastest of the great whales, it is capable of bursts of speed of up to 23 mph (37 km/hr). It is light grey to brownish-black on its back and sides. The underside of its body, flippers, and fluke are white. Fin whales are found in all oceans of the world. They may migrate to subtropical waters for mating and calving during the winter months and to the colder areas of the Arctic and Antarctic for feeding during the summer months; although recent evidence suggests that during winter fin whales may be dispersed in deep ocean waters. Fin whales feed mainly on small shrimp-like creatures called krill and schooling fish. They have been observed circling schools of fish at high speed, rolling the fish into compact balls then turning on their right side to engulf the fish. Their colour pattern, including their asymmetrical jaw colour, may somehow aid in the capture of such prey. They can consume up to 2 tons (1,814 kg) of food a day. During feeding, large volumes of water and food can be taken into the mouth because the pleated grooves in the throat expand. As the mouth closes water is expelled through the baleen plates, which trap the food on the inside near the tongue to be swallowed. Fin whales mate in winter, when they are in warm waters. After a gestation period of about a year, a 6 m calf weighing 2 tons is born. The calf will nurse for 7 months, at which point it will be about 11 m long. Fin whales become mature at around 10 years of age, and may grow up to 18- 23 m long, weighing 40-50 tons. Fin whales calve about once every three years and may live to be 100 years old. The most important factor that affected the fin whale populations was hunting. Since this activity ceased, the populations seemed to have improved. In the Atlantic Ocean, the availability of food, in particular the capelin, is a limiting factor. The fin whales consume a great quantity of capelin and the exhaustion of stocks of capelin could have a harmful effect on the populations. Pollution due to the chemicals is also the cause of debility and mortality. There are no recent estimates of the populations of fin whales since hunting ceased.
[edit] Harbour Porpoise - Northwest Atlantic populationHarbour Porpoises are among the smallest whales; in eastern Canada few individuals exceed 1.7 m in total length and weights of 65 kg. Like all porpoises, they have rounded heads that lack a beak. The sides are a greyish-white and fade to an almost white ventral surface. There is no difference in coloration between males and females, but the calves are usually darker than the adults. Harbour Porpoises are widely distributed over the continental shelves of the temperate northern hemisphere, with two populations in Canada. On the east coast, members of the Northwest Atlantic population are found in the Bay of Fundy north to Cape Aston, and south to North Carolina. The species is well adapted to cold water and is seldom found in water warmer than 16˚C. True to its name, the Harbour Porpoise sometimes frequents bays and harbours, particularly during the summer. The Harbour Porpoise lives to approximately 20 years of age. Female Harbour Porpoises become sexually mature at about three years of age, and mating is restricted to a few weeks in the early summer. The gestation period is 10 to 11 months, and the calves nurse for at least eight months. The diet of the Harbour Porpoise is made up of a variety of small fishes and squid, including cod, herring, hake, capelin, and sand lance. Harbour Porpoises are preyed upon by Great White Sharks, Killer Whales and, in some parts of their range, by Bottlenose Dolphins. Harbour Porpoises are shy animals and intensive human activities in coastal waters may have a negative effect on their populations. The most important recent threat to Harbour Porpoises in eastern Canada is bycatch in bottom-set gill nets used to capture groundfish; this threat has decreased substantially with the depletion of groundfish stocks and consequent reductions in fishing. Other potential threats include: habitat degradation; loss of habitat resulting from the use of acoustic harassment devices, particularly around Salmon aquaculture sites; and environmental contamination by organochlorines (OCs) and polychlorinated biphenyls (PCBs).
[edit] Orca (Killer Whale)The main identifying characteristics of Killer Whales are the distinctive black and white pattern, blunt head, and tall dorsal fin in the middle of the back. The maximum recorded length for a male is 9.0 m, compared with 7.7 m for a female. The tall dorsal fin of adult males is triangular in shape and may reach up to 1.8 m in height. Killer Whales have been observed in all oceans of the world, but they generally concentrate in colder regions and in areas of high productivity. They are found in all three of Canada's oceans, as well as occasionally in Hudson Bay and in the Gulf of St. Lawrence, but they appear to be uncommon in the Atlantic and Arctic. In general, Killer Whales feed on a wide range of prey, including squid, octopus, fish, sea turtles, sea birds, sea and river otters, and other cetaceans. However, individual populations appear to specialize on particular types of prey. Both males and females reach sexual maturity at 15 years of age on average. Gestation periods range from 12-17 months. The interval between calving is usually about 5 years (ranging from 2 to 12 years). Calving occurs year round, but appears to peak between fall and spring. The average life expectancy is about 29 years for females and 17 years for males. Although orcas are widely distributed, total world population is still unknown. They have no natural enemies and have not been hunted as much as other whales. Recent studies suggest that a significant threat to orcas, and other marine mammals, may come from man-made chemicals. Yet, toxins are not the only threats facing orcas. Many fish populations around the world are decreasing. This may be having a direct effect on the populations of fish-eating resident whales. Loss of fish may also cause a decline in seals and sea lions, often the primary prey of transient orcas. We don’t know much about the Atlantic population and more data need to be gathered in order to assess the number of individuals present in this area. The information has been summarized from documents distributed to fishermen along the coast and reproduced with permission of the Minister of Public Works and Government Services Canada, 2005 |
