Piked (Minke) Whale Facts

Taxonomy

Class: mammalia
Order: cetacea
Suborder: mysteceti (which means “moustached” in greek and all are baleen whales)
Family: balaenidae.
Genus: Balaenoptera
Species: Acutorostrata(common) and Bonaerensis (Antarctic)

 

minke whale

Description

Habitat

The Antarctic Minke occurs in polar to tropical waters of the southern hemisphere. It occurs in large numbers south of 60º S, throughout the Antarctic. The distribution is more difficult to assess north of the Antarctic because of its co-occurrence with the common Minke whale. As a result, the boundaries of the species’ winter distributions remain largely undefined. Antarctic Minke is observed off the coast of Brazil and South Africa and there have been occasional sightings in Peru. An unknown proportion of the species remains in Antarctic waters during the winter.

Common Minke whales have a worldwide distribution, appearing in all oceans and some adjoining seas. Cooler regions seem to be preferred over tropical regions.

Although not considered "coastal", these baleen whales rarely venture farther than 169 km from land. They also commonly enter estuaries, bays, fjords, and lagoons. They are also know to move farther into polar ice fields than other rorqual species.

Migration

Minkes are found in all oceans, though they are rarely observed in the tropics. They seem to prefer icy waters, and are found right up to the edge of the icepack in polar regions, and have actually become entrapped in the ice fields on occasion.

Population Numbers/status

Minke whales are the most abundant baleen whale. It is estimated that there are about almost 800,000 Minke whales worldwide .

Feeding

A baleen whale, this species feeds primarily on krill and some small fish. There are regional differences in the diet. Minkes eat krill almost exclusively in the Antarctic, but they are more omnivorous in the northern hemisphere, taking as food squid and small vertebrates such as cod, herring, and sardines.

Antarctic Minke whales feed mainly on krill. Krill comprises 100% of stomach contents of Minke whales caught at the ice edge and 94% (by weight) of the stomach contents of Minke whales in the offshore zone. This is in contrast to common Minke whales, which feed on a more diverse array of fish and invertebrates. Antarctic Minke whales feed primarily in the early morning and late evening, and most feeding activity is observed at the edge of pack ice. Daily food consumption in the summer was estimated at 3.6 to 5.3% of body weight, representing an important proportion of krill biomass in the study area. It is likely that Antarctic Minke whales eat much smaller quantities of food during the austral winter or perhaps forage very little at all on wintering grounds (Best 1982 as cited in Reilly et al., 2008). The blubber layer thickens as the feeding season progresses but mean blubber thickness in individuals has decreased over the 18 year period between 1987 and 2005. This might suggest a decrease in food availability in Antarctic waters.

Minke whales (like all baleen whales) are seasonal feeders and carnivores. They sieve through the ocean water with their baleen. They filters out small polar plankton, krill, and small fish, even chasing schools of sardines, anchovies, cod, herring, and capelin. They have the same diet as blue whales.

The baleen plates in the Minke whale's jaws have about 300 pairs of short, smooth baleen plates. The largest plates are about less than 12 inches (30 cm) long and 5 inches (13 cm) wide. The fine textured baleen bristles are fringed and are creamy-white with pure white bristles.

 

minke whale

Speed/Depth/Breaching

Minke whales can dive for up to 20-25 minutes, but usually make shorter dives, lasting about 10-12 minutes. Just before diving, Minke whales arch their back to a great degree, but the flukes do not rise out of the water. Minke whales breathe air at the surface of the water through 2 blowholes located near the top of the head. At rest, Minke whales spout (breathe) about 5-6 times per minute. The spout of the Minke whale is a very low, almost inconspicuous stream that rises up to 6.5 feet (2 m) above the water. Minke whales start to exhaling before they reach the surface; this minimizes the blow. Minke whales normally swim 3-16 mph (4.8-25 kph), but can go up to 18-21 mph (29-34 kph) in bursts when in danger. Feeding speeds are slower, about 1-6 mph (1.6-9.8 kph).

Reproduction

The breeding period is long--from December to May in the Atlantic and year round in the Pacific. Peak months for births are December and June. Minke whale breeding occurs while the whales are close to the surface and in warm waters. Growth stops at about 18 years for females and 20 years for males. Minke whales reach puberty at 2 years of age.

Only one young is born at a time. Gestation lasts for 10 to 11 months, with the calf being born near the surface of warm, shallow waters. The newborn instinctively swims to the surface within 10 seconds for its first breath; it is helped by its mother, using her flippers. Within 30 minutes of its birth the baby whale can swim. Weight at birth is 1000 pounds (450 kg), with a length of about 9 feet (2.8 m).

The baby is nurtured with its mother's milk. The young are weaned at 5 months, but they do not become sexually mature for 6 years. The mother and calf may stay together for a year or longer. Females are thought to have young every other year.

Interesting Facts & History

Minke whales travel either singly or in small groups (2-4), although they can be found in large aggregations in the hundreds where krill is abundant. They are thought to be curious, approaching ships and wharfs which is not typical of its family. They are also highly acrobatic, able to leap completely out of the water like a dolphin. Minkes are fast swimmers. Some populations are migratory – both southern and northern populations often spend winter in tropical waters, although these are actually at different times of year as a result of seasonal differences in their homelands.

Only in recent decades have Minke whales been taken by whalers to any extent; they were thought to be too small to be a worthwhile catch. But as the larger whale species became depleted, the whalers began to hunt the Minke as a replacement. Since the late 1960s and 1970s, Japan, Russia (which has now ceased whaling), and (to some extent) Norway have focused their whaling efforts on Minke whales. Scientists are still examining the populations of Minke whales in areas where they are harvested, and have discovered that the largest numbers of Minkes are found in the southern hemisphere. It is thought that Minke populations have increased as they started to eat the food that was previously eaten by the now-depleted large whale species. The present population worldwide is believed to be over a million animals.

Minkes tend to be solitary animals, though sometimes they are seen traveling in pairs or in small groups of 4 to 6. In the polar regions, where food is concentrated, it is common to find larger aggregations of feeding animals in an area. They appear to segregate by age and sex more than do the other baleen whales. Females remain close to shore, while males are farther out to sea.

Some Minkes migrate long distances, but others may move only within a restricted area. In some regions, Minkes may be found year-round. Their life span is believed to be about 50 years. Killer whales are known to prey on Minkes, especially in parts of the southern hemisphere.

The taxonomy of Minke whales is currently in question, and soon there may be three species of Minke whales: the Antarctic Minke whale (relatively large and lacking a flipper stripe), the dwarf Minke (smaller than Antarctic, has a flipper stripe, lives in tropical southern hemisphere waters), and the true Minke whale (flipper stripe present, lives in the northern hemisphere).

Conservation Efforts

Sea Shepherd is leading the effort to defend and protect Minke whales from the harpoons of the illegal Japanese whalers in the Antarctic.