Right Whales (Eubalaena glacialis)
Right Whales on the Ledge: Until recently, Jeffreys Ledge was nopt thought to be an important area for right whales. Recent work, however, has shown that this area may be more important than previously thought. The mid-summer period tends to be a time when a few animals, primarily mothers with calves, are seen briefly on the Ledge. These are probably transient animals moving to and from the Bay of Fundy and the Nova Scotian shelf, where most right whales summer. In the fall, however, right whales seem to use the Ledge as a feeding habitat. In some falls we have recorded numbers of animals, some spending up to several weeks feeding on the Ledge. Up to 20 animals have been seen in a single day, despite minimal effort during the October through December period.
Size: 45-55 feet as adults
Weight: approximately 40-50 tons as full grown adults
Distinctive Characteristics: A stocky rotund body with no dorsal (back) fin; hardened patches of skin called 'callosities' on their head, often covered by colonies of cyamids ('whale lice'); a high, arching lower jaw and very long baleen plates with a fine fringe.
Diet: Exclusively plankton feeders, using a skim feeding technique (see photo). In the northern hemisphere copepods are the primary prey, while krill are the primary prey in the southern hemisphere.
Distribution: Right whales are distributed world-wide, with three major distinct populations: the North Atlantic, North Pacific, and southern oceans. There are two species of right whales: northern right whales, which are found in the North Atlantic and North Pacific ocean, and the southern right whale, which is only found in the southern hemisphere. Like humpback whales, there appears to be a seasonal migration for at least a portion of the population from cold water summer feeding grounds to warmer water winter breeding grounds. However, there may also be a substantial portion of the population which does not migrate as extensively, and may spend the full year in colder waters. In the North Atlantic, whales summer in the Bay of Fundy and Nova Scotian shelf; pregnant females and juveniles then move to coastal Georgia and Florida for calving. Some right whales spend the late winter and early spring feeding in Cape Cod Bay and the Great South Channel on George's Bank. Distribution in the North Pacific is largely unknown, and sightings are uncommon. In the southern hemisphere, whales probably feed below the Antarctic convergence, and move to coastal breeding grounds off Australia, South Africa, and South America.
Life History: Right whales are born during the winter at 10-15 feet and approximately 3,000 pounds after a 12-14 month gestation. Calves stay with their mother for up to a year, although the calf of a mother killed by a ship collision when only 8 months old did survive and was sighted in subsequent years. Right whales have been observed to give birth as early as five years of age, but seven to ten appears to be more common. Calves are born once every 3-4 years, and the mother is entirely responsible for caring for the offspring. Right whales can live extremely long lives; one whale photographed back in 1935 with a calf was re-photographed as recently as 1995, making her the oldest non-human mammal ever confirmed.
Social Organization: Right whales are usually solitary feeders, although dense plankton swarms in a limited areas may attract a number of whales to the same location. Cooperative feeding, as often seen in fish feeding whales such as humpbacks and fin whales, is uncommon. Right whales do aggregate into apparent mating groups, where numerous males compete for access to an adult female. Up to 35 males have been seen in a single group! It is thought that multiple males may mate with a single female, and much of the actual competition for fathering offspring is internalized in the female, through sperm competition. These 'surface active groups' are observed year-round, even though the calving season is highly seasonal. No one knows whether these groups have some other social function besides reproduction.
Population Status: Right whales got their name because to early whalers they were the 'right' whale to kill: they were slow swimmers, lived close to shore, floated when dead, and gave a good oil yield when their thick fat layer was melted down. Right whales were hunted as early as the 11th century, and were probably endangered by the mid-1800's. They were protected world-wide in 1937, although there have been both 'research' kills and illegal takes long after that date. Currently, there are approximately 4,000 southern right whales. Some 300 right whales remain in the North Atlantic (with the population growing at an average of only 2.5% per year, as opposed to a 7-8% annual growth of southern right whale populations), and an undetermined small number (probably less than 100) live in the North Pacific. Collisions with ships are the largest single cause of human mortality, but entanglements in fixed fishing gear have at least scarred almost 60% of the whales in the North Atlantic. Preliminary evidence also suggest that North Atlantic right whale populations have dropped to the point where they have lost some genetic diversity, and inbreeding may also be a problem in their recovery.
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