BLUE WHALE (Balaenoptera musculus)

IDENTIFICATION

Size
- to a maximum length of 30 metres

Colour
- blue-grey, mottled in appearance
- skin of some individuals has yellow-brown patches caused by diatoms

Dorsal fin
- variable in shape from triangular to curved toward the back and rounded at the tip
- looks very small relative to overall body length - 1/3 metre in height, positioned so far back that it is not seen until after the head has submerged and whale is about to dive, long after the blow is seen

Blow
- tall, slender and vertical, upwards of 9 metres in height

Tail fluke
- sometimes raised prior to final dive, very broad with a straight or slightly concave bottom edge with a slight notch in the middle
- very broad tail, size can be up to 1/4 of body length

Surface behaviour


Group size / social behaviour

Other characteristics
- very broad, flattened, U-shaped head

Can be confused with
- sei and fin whales – especially from a distance due to the extremely tall blows of all of these species. However, the distinctive blue-grey coloration and vast size of blue whales distinguishes them from all other whales.

NATURAL HISTORY

Blue whales are a cosmopolitan species with a wide-spread distribution in most of the world’s oceans. They can be found in both coastal and pelagic waters. Due to commercial whaling, their global population has been significantly reduced; at present it is unclear how many blue whales remain in the ocean due to their large range and dispersal, as well as low sampling efforts. In Canada, blue whales are present on the Pacific and Atlantic coasts. Through studying distinctive calls it is believe that there are at least two distinct populations within the north Pacific; one occupies the western and central north Pacific, while the other occupies the eastern north Pacific.

Blue whales appear to be migratory, spending summer month in higher latitudes and winter in lower. Some tropical areas, however, have shown certain whales present year round, indicating possible non-migratory blue whales. The whales that frequent the waters off British Columbia are most likely the same whales that feed off California in the summer/fall and spend the winter months in Mexico and Central America. They are capable of covering long distances in short periods of time; one animal was documented travelling from the Queen Charlotte Islands to the Santa Barbara Channel, a distance of 2500km in 28 days or less. Researchers are able to identify individual blue whales by the pigmentation and mottling patterns on their flanks. Much of this photo-identification has taken place in California, a hotspot for blue whale sightings. In 2007, researchers from Fisheries and Oceans Canada spotted 5 different blue whales off of Haida Gwaii in British Columbia.

Blue whales feed on zooplankton, most commonly a variety of euphasiid (krill) species, as well as some copepods. Blue whales are a ‘rorqual’- meaning they have pleats along their throat. This allows them to expand their throat while feeding, and then expel salt water through their baleen, which acts as a food sieve. To feed, blue whales lunge through swarms of krill, sometimes on their side or back. This may be observed above water, but most surface-feeding probably happens at night, when krill concentrations rise in the water column. Due to their enormous size blue whales must eat several tons of zooplankton a day. This large energetic demand may mean their range and recovery is constrained by food availability. Climate change and other oceanographic shifts may greatly affect zooplankton and, therefore, the blue whale. The majority of feeding happens in high latitude water, usually in productive upwellings along the continental shelf break.

No breeding grounds for the blue whale are known in the world, but it is believed that reproduction happens in the winter in tropical/sub-tropical waters. For example, females and calves are often spotted in the Gulf of California, Mexico. Females have a gestation of 10-12 months and will nurse for 6-7 months. Most likely, the calves are weaned in the summer on the feeding grounds. Females and males reach sexual maturity between 5 and 15 years of age, and a female has a birthing interval of 2-3 years.

The vocalization of a blue whale may be the loudest sound made by an animal. Most of their calls are low frequency and infrasonic; the human ear does not hear them. These types of calls can travel huge distances (100s-1000s of kilometers) and are well-suited for an animal that has such a large dispersal, enabling communication between animals very far apart. Acoustics are increasingly being used to understand the range of the blue whale and to some degree, their abundance. Off British Columbia, blue whale calls are most consistently heard between October and February.

It is unclear exactly how many blue whales would have been present in the north Pacific prior to whaling. However, it is estimated that 9500 blue whales were taken from north Pacific by commercial whalers. In BC, at least 650 blue whales were killed between 1900 and 1967. Blue whales may be preyed upon by killer whales, though this is thought to be an unusual occurrence in most of their range.

STATUS IN CANADA

The blue whale is designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

COSEWIC’s assessment of the Pacific population of the blue whale is as follows:

Blue Whales off the coast of British Columbia are likely part of a population based in the northeastern Pacific. The population was reduced by whaling. The rarity of sightings (visual and acoustic) suggests their numbers are currently very low (significantly less than 250 mature individuals). Threats for blue whales along the coast of British Columbia are unknown, but may include ship strikes, pollution, entanglement in fishing gear, and long-term changes in climate (which could affect the abundance of their zooplankton prey).

Blue Whale
Blue Whale
Alana Phillips
Blue Whale
Alana Phillips
Blue Whale
Alana Phillips
Blue Whale
Alana Phillips
In 2007, researchers from DFO and Cascadia Research found 5 blue whales off Haida Gwaii
Alana Phillips
In 2007, researchers from DFO and Cascadia Research found 5 blue whales off Haida Gwaii
Researchers approach a blue whale to obtain photos and DNA samples
Alana Phillips
Researchers approach a blue whale to obtain photos and DNA samples
Blue Whale

FIN WHALE (Balaenoptera physalus)

IDENTIFICATION

Size
- to a maximum length of 22 metres

Colour
- dark gray to brownish black on back and sides
- no mottling like the blue whale
- undersides are white
- right lower lip is white and the left lower lip is dark - this asymmetrical head colouration is a diagnostic feature that can be reliably used to differentiate fin whales from other species of large whales

Dorsal fin
- 2/3 metre in height, sickle shaped and curving towards the back
- is seen shortly after the blow

Blow
- narrow, cone shaped, up to 6 metres in height

Tail fluke
- slightly concaved bottom edge with distinct notch in the middle
- fin whales rarely lift the tail fluke prior to a deep dive

Surface behaviour
- unlike blue or sei whales, fin whales occasionally leap clear of the water

Group size / social behaviour

Other characteristics
- head is V-shaped

Can be confused with
- blue and sei whales – especially from a distance due to the extremely tall blows of all of these species. However, the dark coloration and the larger dorsal fin that is seen shortly after the blow distinguishes fin whales from blue whales, and the distinctive white coloration on the right lower jaw distinguishes from sei whales, which are also very rare in BC waters.

NATURAL HISTORY

Fin whales are a cosmopolitan species, found throughout the world’s oceans in coastal and pelagic waters. They seem to be most abundant in polar and temperate areas. In Canada there is both an Atlantic and Pacific population of fin whale. In British Columbia, fin whales are seen in summer and winter months, most commonly in offshore waters, Hecate Strait and Queen Charlotte Sound. It is still unclear how many different stocks of fin whales are in the north Pacific and if the fin whales found in BC are more closely associated with those found in Alaska, or those in the California/Washington/Oregon range.

Fin whales feed primarily on small invertebrates, schooling fish and squids. In the north Pacific 70% of their diet was found to be made of euphasiids, while another 25% were copepods. Fin whales are a rorqual, meaning they have a pleated throat. They are able to take in up to an incredible 70 tonnes of food-rich saltwater into their extended throat and then use their baleen to sieve out the food as they expel saltwater.

Little is known about the breeding behaviours and areas of the fin whale. It is believed that it happens in lower latitudes during the winter months, but as of yet, no breeding ‘grounds’ for fin whales have been found. It is possible that due to the long-distance communication fin whales are capable of, they may not need a specific geographical location in order to find breeding partners. Both sexes are estimated to reach sexual maturity between 5-15 years of age and females appear to have a calf every 2-3 years. Their gestation is between 11-12 months, after which the calves are weaned at 6-7 months. Interestingly, hybridization between fin and blue whales is not uncommon. Hybridization can happen between either sex of either species, and it is yet unknown the reproductive capacity of these hybrids.

Fin whales appear to have a long lifespan between 50-100 years, with females growing slightly (5-10%) larger than males, though at a slower rate. Data on fin whale size and growth has mostly been compiled through whaling records. Fin whales were heavily targeted by coastal whaling in the Pacific northwest until the 1970s. Currently, fin whales are threatened by ship strikes. Fin whales are the most commonly struck whale world wide, though why this is the case is unclear. Speed may play a factor as vessels travelling over 14 knots have a much higher likelihood of fatally hitting cetaceans. Between 1999 and 2004, at least 6 fin whales were hit and killed around Canadian Pacific waters.

STATUS IN CANADA

The fin whale is designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

COSEWIC’s assessment of the Pacific population of the fin whale is as follows:

Currently sighted only infrequently on former whaling grounds off British Columbia. Coastal whaling took at least 7,600 animals from the population between 1905 and 1967, and thousands of additional animals were taken by pelagic whalers through the 1970s. Catch rates from coastal whaling stations declined precipitously off British Columbia in the 1960s. Based on the severe depletion and lack of sufficient time for recovery, it is inferred that present population is below 50% of its level, 60-90 years ago. Individuals continue to be at risk from ship strikes and entanglement in fishing gear.

Fin Whale
Fin Whale
Alana Phillips
Fin whale
Alana Phillips
Fin whale
White right jaw
Fin whale
John Ford
Fin whale
Fin whale
John Ford
Fin whale
Fin Whale

SEI WHALE (Balaenoptera borealis)

IDENTIFICATION

Size
- to a maximum length of 16 metres

Colour
- dark to bluish grey, often with many grey to white scars

Dorsal fin
-1/4 to 2/3 metre high, strongly curved towards the back
- generally more erect compared to a fin whale
- less than 2/3 from the front of the body

Blow
- up to 3 metres in height
- resembles the blow of a blue and fin whale, but is neither as high nor as dense

Tail fluke
- seldom arch tail high or expose flukes

Surface behaviour

Group size / social behaviour

Other characteristics
- blowhole and dorsal fin seen simultaneously

Can be confused with
- fin whales – especially from a distance due to the tall blows and dark coloration of these species. However, the larger size and distinctive white coloration on the right lower jaw of fin whales distinguishes them from sei whales.

NATURAL HISTORY

A sei whale’s diet and feeding behaviour are more similar to those of a right whale than to other rorquals such as blue and fin whales. They feed mainly on copepods and are thought to skim the surface for their prey. They are also known to feed on fish and squid if they are encountered.

There have been few sightings of sei whales since the cessation of whaling.

In the eastern north Pacific, the reported take of sei whales by commercial whalers totaled 61,500 between 1947 and 1987.

Starting in 1962, the number of sei whales targeted by whalers in B.C. spiked to over 500 whales a year, after populations of blue and fin whales had been reduced by overharvesting. By 1967, whalers were only able to catch 100 sei whales, because their population was now overharvested, too. Between 1924 and 1967 more than 3200 sei whales were taken by whaling stations in B.C.

STATUS IN CANADA

The sei whale is designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

COSEWIC’s assessment of the Pacific population of the sei whale is as follows:

This was one of the most abundant species sought by whalers off the British Columbia coast (with over 4000 individuals killed) and was also commonly taken in other areas of the eastern North Pacific. Sei whales have not been reported in British Columbia since whaling ended and may now be gone. There are few, if any, mature individuals remaining in British Columbia waters, and there is clear evidence of a dramatic decline caused by whaling and no sign of recovery.

Sei Whale
Sei Whale