Minke Whale
Size: 7-10 m ( ft)
Weight: 5-7 tonnes
Diet: Mostly small schooling fish such as sandeels and capelin, but also krill and opportunistically other small schooling fish species
The minke whale is a baleen whale that belongs to the rorqual family and is its smallest member. Other rorquals are e.g. the blue whale, the fin whale and the humpback whale. The minke whale is one of the most common whales spotted off the coast of Iceland and can be seen near the coast all year round. Its Latin name, acutorostrata, refers to its very narrow or pointed snout, as acuto means sharp and rostrata (or rostrum) means snout or beak. The narrow snout and streamlined body make it easy for the minke to slice through the water and achieve considerable speeds when swimming through the deep. When minke whales surface from diving, the first evidence of their presence is often the narrow snout breaking the surface. The dorsal fin is fairly high and curves backward, making it easy to recognize this whale at sea. The shape of the dorsal fin along with scars and notches on it, make it possible for whale experts to recognize individual animals. Minke whales in Icelandic waters have a characteristic white band across their pectoral fins, a characteristic unique to North Atlantic minke whales.
Behavior
Minke whales are more or less loners, as is common with baleen whales, but they do sometimes gather in smaller groups with 2–3 individuals when feeding or travelling. They can often be seen in larger groups in small areas if food is abundant. They usually return to familiar feeding grounds every summer. Studies of minke whales in the Faxaflói bay have shown that certain animals return year after year. Females are usually the first to appear in the feeding grounds around Iceland, and the number of males increases as the summer progresses. Minke whales can use a number of gulping techniques when feeding, although each individual tends to specialize in a single hunting technique. Minke whales are quite curious and sneak up on boats, dive under them and then stick their heads up out of the sea. Such whales are called spy-hoppers. Minke whales sometimes propel themselves at speed from the deep, leap to considerable heights and then crash back down with huge splashes. Some say that the minke whales are are trying to get rid of whale lice with this behavior, although the reason for this energy intensive but enjoyable behavior is not known.
Minke whale dives are usually of short duration, or 3–10 minutes at a time, although they can dive for up to half an hour. They seldom dive deeper than 100 m (328 ft.). Minke whales can swim quite fast and can achieve up to 40 kph (25 mph) in short bursts. They have considerable endurance and can maintain speeds of 15–30 kph (9-19 mph) for up to an hour. This shows how well adapted their bodies are to water, as the water resistance is kept to an absolute minimum. The body shape and muscle mass of minke whales allow them to reach considerable speeds and to maintain such speed for quite some time without spending too much effort. Minke whales take advantage of their endurance to out-pace killer whales. Their endurance is their main protection against predators.
Reproduction
The females can calve every year. Gestation is around 10 months, and as a result, the females can become pregnant while they have a suckling calf. In the North Atlantic, minke whales calve, between October and March, and mating reaches its peak in February. Females usually give birth to a single calf which suckles for a relatively short period, or for 4–6 months. As the milk is especially nutritious, the calf quadruples in weight and doubles in length during this period.
Vocalization
Minke whales emit very loud sounds, or around 150 dB. The sounds that they emit are varied and sometime very strange. The sounds heard near Iceland and elsewhere in the North Atlantic tend to be thump series, ratchets, clicks and grunts. Researchers have also heard multi-tone sounds at quite high frequencies (1–5 kHz), which sound very much like someone hitting a false note, called a “boing” noise, which has, as yet, only been heard in the Pacific Ocean. Other special sounds resemble the sounds of the laser guns in the Star Wars films and have been named the “Star Wars call”, but such sounds have only been heard from minke whales off the coast of Australia
Habitat and distribution
Minke whales can be found in most oceans. They prefer shallow waters and are common therefore in coastal areas, setting them apart from most baleen whales, which usually prefer deep oceans. Minke whales travel toward the polar regions during summer and toward the Equator during autumn and winter. Some do not migrate and remain in the colder feeding grounds throughout the winter. There are always some that choose to remain in the waters around Iceland during the winter.
Life expectancy and population size
Minke whales are believed to have a maximum life-span of 40–50 years. There are four distinct stocks of minke whale in the North Atlantic. The distinction is based on the genetic aspects of the whales and their food selection. Minke whales frequenting Icelandic water belong to the Mid-North Atlantic Ocean stock, whose habitat is near the east coast of Greenland, the coast of Iceland and east of Jan Mayen during the summer. The population of this stock is believed to be around 40,000 animals, and the entire population in the North Atlantic is believed to be 140,000.
The main natural enemy of minke whales is the killer whale, which has been observed to hunt minke whales near the coast of Iceland. Other threats are mainly due to humans, and there are examples of minke whales becoming entangled in fishing nets and drowning. In addition, this whale species competes considerably with man as regards food resources. Increased shipping through feeding grounds, moreover, has negative effect on minke whales’ feeding success. Minke whales are hunted commercially in Norway, Iceland and Japan, and indigenous hunting is practiced in Greenland. Iceland’s minke whale hunting quota is 200 animals per year but 38–60 animals have been caught per year since 2010.
Edda Elísabet Magnúsdóttir, Marine Biologist