THE NORTH ATLANTIC RIGHT WHALE

 

 

Right whales have a large, stocky body in which the girth can be sixty percent of body length. Usually the body tapers to a narrow tail and the whale possesses large spatula-shaped flippers, a smooth back without a dorsal fin and there are no ventral grooves or pleats.  The huge head is about one-quarter of body length and features a bowed lower jaw that enfolds the long, narrow, highly arched upper jaw.  Callosities are irregular crusty protuberances of horny keratin found in patches on the head of right whales and these distinguish right whales from all other whales.  The largest callosity is called the bonnet and is located in front of the two blowholes.  Right whales only rarely deeply dive and they can remain underwater for twenty minutes. These can be very acrobatic whales that often breach and smack the water with their tail flukes and flippers.  North Atlantic right whales can be sixty feet long and weigh 100 tons.  The V-shaped blow is a spout of water about fifteen feet high.

Both genders of the North Atlantic right whale attain sexual maturity between five and ten years of age.  Mating and calving occur in winter and one female whale may mate successively with several male whales.  The impressive size of male right whale testicles ( being in excess of 900 kilograms in weight ) suggests that right whale reproduction is based on sperm competition.  Female right whales carry the baby whales in their womb for twelve months ( gestation period ). Nursing lasts six to seven months, occasionally 18 months.  Right whales engage in sexual behaviour even when it is not mating season.

Right whales feed primarily upon krill and copepods, with copepods being the predominant components of their diet.  Right whales possess 206 to 268 narrow, dark baleen plates, each plate being up to 8 feet long, on both sides of their mouth.  The baleen is fringed with long, fine greyish bristles and functions as a kind of sieve to strain out krill and copepods from the water the whale swallows and then expels from between the baleen plates.  Right whales are skim feeders that move through the water with their mouths agape.  North Atlantic right whales are primarily solitary but also gather in pairs and in small, unstable groups of ten to forty whales.  Right whales gather in regions where thermal fronts, topography and cold water upwellings give rise to high concentrations of copepods and krill.  Right whale vocalizations include low-frequency moans and belches, growling, squealing, percussive sounds and odd high pitched sounds in the 1500 to 2000 Hz range. Usually right whales vocalize using low frequencies below the 500 Hz threshold.

There is generally only one ovulating female right whale for every four male right whales thus leading to intense competition for mates.  Present models indicate that the North Atlantic right whale will go extinct in about 208 years since it is experiencing a 2 percent decline in population numbers every year.  Despite the fact that hunting of North Atlantic right whales has ceased for seventy years the high incidence of ship strikes and fishing gear entanglements may still doom this species to final extinction. Ship strikes and fishing gear entanglements accounted for 46 percent of all North Atlantic right whale mortality between 1970 and 2001.