Maximum number of baleen plates on upper jaw
Average weight of a newborn
Maximum time between breaths
Grey whales are a medium sized baleen whale, easily recognized by their mottled grey appearance and quiet surface behaviour. Much of their body is covered with white barnacles, whale lice, and scratches and scars leaving their grey colouring to appear marbled and blotchy. Similar in size to the humpback whale, they are distinctly different in appearance and behaviour. Grey whales lack a dorsal fin, instead having a small dorsal hump about ⅔ down its back followed by a series of ‘knuckles’ that extend down the dorsal ridge towards the flukes. Their robust body, with a relatively narrow head and blunt snout, and small paddle-shaped pectoral flippers are ideal for shallow coastal waters. Behaviourally, they are very unobtrusive at the surface, rarely breach, and are sometimes referred to as a ‘breathing rock’. Adult males measure 13.7-14 m while adult females measure slightly larger. Both sexes weigh 30-40 tons.
A grey whale's pectoral flipper is often raised out of the water when a whale turns on its side to feed in shallow, inshore waters.
Grey whale tail fluke.
Grey whales are very unobtrusive at the surface, rarely breach, and are sometimes referred to as a ‘breathing rock’.
Much of a grey whale's body is covered with white barnacles, whale lice, and scratches and scars leaving their grey colouring to appear marbled and blotchy.
Grey whales lack a dorsal fin, instead having a small dorsal hump about two-thirds down its back followed by a series of ‘knuckles’ that extend down the dorsal ridge towards the tail flukes.
Grey whales have a relatively narrow head and blunt snout.
Grey whales inhabit shallow coastal waters of the North Pacific where they occur in two distinct populations – the western grey whale population inhabiting the coasts of China, Korea, Japan, and Russia; and the eastern grey whale population inhabiting Canada and the United States. Eastern grey whales have one of the longest seasonal migrations of any mammal, summering in northern temperate waters to feed and migrating south in the winter to warmer, shallow lagoons for calving.
Eastern grey whales spend winters, from January to March, in the warm waters of Baja California, Mexico, where pregnant females give birth. By late February, they start swimming northward. Adult males, newly-pregnant females and juveniles leave first, followed by females and their calves. Some grey whales start feeding when they reach the waters along Vancouver Island, although in some years, some start feeding as far south as central California.
During the summer months, most grey whales feed in the Bering Sea, Chukchi Sea, western Beaufort Sea, and the Arctic Ocean. Here they gorge themselves on massive quantities of food! Grey whales rely almost entirely on their fat reserves as an energy source during their winters and migrations so they build up their blubber and other fat reserves by feasting through the summer months. They gain 16 to 30 percent of their body weight during this time. In October, as the northern winter begins, pregnant females lead the procession of migrating grey whales returning to the warmer waters of Baja California.
Each spring, thousands of people flock to Pacific Rim National Park on Vancouver Island hoping to catch a glimpse of migrating grey whales heading up to their summer feeding grounds. Since the whales often travel close to the shoreline, many park visitors are able to spot the whales from the beach!
A small population of a few hundred animals known as “summer resident” grey whales or the “Pacific Coast Feeding Aggregation” remains in the inshore waters of Washington and British Columbia (B.C.) during the summer instead of continuing the migration to Alaska. These animals can be seen in Washington off the Oregon Coast and Puget Sound around Whidbey Island; and in B.C. they’ve been seed feeding in Boundary Bay near Delta, along the western side of Vancouver Island, and the northern end of Vancouver Island.
Grey whales are a baleen whale meaning they having baleen in their mouth instead of teeth. Baleen is made up of keratin-based, comb-like plates that filter the water for food. These enormous animals eat large quantities of tiny prey. Scientists believe an adult grey whale consumes an average of about 1,100 kg of food per day. The main component of their diet is small, shrimp-like animals called amphipods that live on muddy ocean floors. Grey whales also eat tubeworms, mysids (another shrimp-like animal), small fishes, ghost shrimps, herring eggs, and crab larvae (especially larvae of porcelain crabs), which are a seasonally important food source for them in B.C.
Grey whales feed in inshore, shallow waters. Unlike other baleen (filter feeder) whales, grey whales are bottom feeders and use their coarse baleen to strain out small invertebrates (amphipods, ghost shrimp, and crab larvae) from the soft muddy bottom in shallow areas. They use suction to draw food into their mouths. A feeding grey whale turns so that one side of its mouth faces the ocean bottom. The whale opens its mouth slightly and pulls in its huge tongue. This draws in sediment and amphipods from the ocean bottom. The whale then pushes the sediment through the baleen plates on the opposite side of its mouth. The amphipods are caught in the baleen, which acts like a filter.
Grey whales are the only baleen whale that regularly feeds on bottom-dwelling animals. When feeding they make sharp turns in the shallow water and may raise their pectoral fins and/or tail flukes out of the water, giving the impression that the whale is struggling or stranded; however, this is normal feeding behaviour. Scientists think they can tell whether a grey whale is a right or left-handed feeder by looking at the barnacles and scraped skin on its head. There are more skin scratches, and fewer barnacles, on the side of the whale that faces the bottom when it feeds. Sometimes grey whales use other feeding techniques such as surface skimming for crab larvae.
Grey whales are not highly social and only come together during the breeding season and parts of their migration. Grey whales are mammals and give birth to live young. Gestation is 12-13 months and females bear a single calf at intervals of 2 or more years. Calves are born in Mexico during the winter months and are typically up to 5 metres long and weigh about 900 kg at birth. Courtship and mating behaviour is complex, and frequently involve 3 or more whales of mixed sexes. Mothers and calves have a strong bond for the first few months, and mothers often stroke their calf with their flippers. Calves wean at around 8-10 months.
Grey whales’ primary predator is Bigg’s (mammal-eating) killer whales, which attack grey whale calves and yearlings along their migration route. Mothers are fiercely protective of their calves from attacking killer whales, who often give up the attack if a mother grey whale is particularly aggressive in her defence. Ocean Wise Marine Mammal Research Program scientist Dr. Lance Barrett-Lennard and colleagues studied killer whale predation on grey whales in False Pass, Alaska – a narrow passage through which the majority of grey whales pass on their migration to the Bering Sea each spring. Here Biggs’ killer whales have adapted a unique behaviour of caching dead grey whales in shallow waters so that they can consume most of the carcass over the course of several days. Carcasses that wash up on nearby shores also provide an important source of nutrition for brown bears that are just emerging from their hibernation dens. Lance and his team estimate that transient killer whales may take up to a third of the calves born to the Eastern Pacific grey whale population each year.
Historically, grey whales were hunted by the Chukotka people of the US/Russian Arctic, as well as many coastal First Nations in B.C. and Washington. Grey whales were hunted commercially for their meat and oil by European, Japanese, and North American whalers, especially in the 17th and 18th century. Relentlessly hunted for their meat and oil, Atlantic grey whales became extinct in the 18th century. The western grey whale population was hunted almost to extinction with a critically endangered population estimated at fewer than 100 animals today. The eastern North Pacific population was also extensively hunted but since being protected has made a dramatic comeback to around 18,000–24,000 animals today.
Grey whales are no longer hunted commercially. In the late 1940s, a convention under the International Whaling Commission (IWC) prohibited the commercial whaling of grey whales. These restrictions enabled grey whales to make a dramatic comeback to current population levels. However, subsistence hunting still occurs in Russia and the US Arctic. The Makah tribe of Washington State is also negotiating the right to hunt grey whales for subsistence purposes.
In Canada eastern grey whales are listed as “special concern”. Following the cessation of whaling, the population increased significantly reaching, what is believed, pre-exploitation levels of about 27,000 animals in 1998. However, this population size could not be sustained and over ⅓ of the population died from 1998 to 2002. Although the population seems stable again, grey whales are susceptible to human activities in their 4 breeding lagoons in Mexico, and throughout their range entanglement in fishing gear, collision with boats, and underwater noise.
The lifespan of grey whales is unknown; however, whaling data suggest they may live well over 80 years. Grey whales may reach puberty around 6-12 years of age, and reach full size around 40 years-old.
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