Northern Ireland's Priority Species

Balaenoptera acutorostrata – minke whale

 
Balaenoptera acutorostrata

Balaenoptera acutorostrata Lacepede, 1804
Family: Balaenopteridae

The minke whale is the smallest and most common of the baleen whales found around the coast of Northern Ireland.

Before 1930, the whaling industry rarely bothered to hunt minke whales because larger whale species such as the fin, blue and sei were still plentiful and brought a higher profit per catch (the main by-product at this time was whale oil). Eventually, large whales, became hard to find, many species had been hunted almost to extinction, and the whale hunters turned their attention to the smaller minke whale. By the early 1980s, the minke was the most hunted whale species in the North Atlantic.

In 1986, the International Whaling Commission issued a moratorium on commercial whaling. Despite this, some countries continue to hunt whales. Japan plans to catch nearly 1,000 minke whales for research purposes in 2005/2006; meat obtained from these whales can be sold for food in restaurants and schools.

Norway resumed commercial whaling in the north-eastern Atlantic in 1993 under objection to the IWC moratorium – over 4,000 minke whales have since been killed.

In brief

  • Found in the seas around Northern Ireland

  • Most likely to be seen from May to October

  • Listed as a UK Priority species

  • Still threatened by whaling in the North Atlantic and Antarctic – 500 to 1000 minke whales are taken annually.

Species description
The head is flat, narrow and pointed with a sharp central ridge that runs from in front of the two blow holes to the edge of the upper lip. Numerous throat grooves (between 50 and 70) extend halfway along the body and allow the throat to expand when the whale is feeding. There are between 200 and 350 short (less than 20cm long) cream/yellow baleen plates on each side of the upper jaw.

The body is slender and rarely longer than 10m. The upper parts are dark – black, brown or grey, the underside is pale/white. The pointed flippers have a distinctive diagonal white band across the middle of the upper surface. The dorsal fin is curved or hook shaped and located nearly two-thirds of the way along the back towards the tail.

The blow is small (3m) and not easily seen even in calm water. Minke whales can stay underwater for up to 20 minutes, but dives usually last between 3 to 8 minutes.

Life cycle
Minke whales are found throughout the world’s oceans. There are three geographically distinct populations – in the North Pacific, North Atlantic and Southern Hemisphere. They appear to be more common in cooler waters and are often seen inshore. Minke are fast swimmers and can reach speeds of up to 20 kilometres per hour. Some populations are thought to migrate, feeding in colder waters in summer, then moving to warmer waters in winter where breeding takes place and the young are born (December/ January). Minke whales are thought to become sexually mature at around six or seven years of age. Pregnancy lasts about 10 to 11 months and a single calf may be produced every two years. At birth, the calf weighs about 450kg and measures 2 to 3m. It is suckled for about seven months and grows rapidly. Minke whales may live for up to 50 years. Minke whales are usually seen singly but, where feeding is good, small groups of two or three may be seen. They generally feed on small fish such as herring, but will also take squid and krill.

Similar species
May be confused with the sei, fin or Northern bottlenose whale. The sight of the blow and the dorsal fin at the same time occurs only with sei and minke whales. Only minke whales have white bands on their flippers.

How to see this species
Sightings off the coast of Northern Ireland have increased over recent years as whale-watching becomes more popular. The best places for whale-watching are headlands, islands and bays when the sea is calm.

Young minke whales are inquisitive and may approach or follow boats and will perform acrobatic displays such as spyhopping or breaching.

Current status
The world population is estimated to be between 610,000 and 1,284,000 with around 200,000 occurring in the Northern Hemisphere.

Minke whales are regularly seen off the Northern Ireland coastline. They are protected under schedule 5 in the Wildlife (Northern Ireland) Order 1985. Whale hunting is illegal in Northern Ireland waters.

Why is this species a priority in Northern Ireland?

  • Listed as a UK Priority Species.

Threats/Causes of decline

  • Commercial hunting for minke whales in the North Atlantic presents a major threat to the UK population

  • Entanglement in fishing gear

  • Collisions with ships

  • Attacks by killer whales

  • Ocean pollution (chemical and noise).

Whales and dolphins communicate mainly by sound and they also use sound to navigate and find food. Many man-made sounds are introduced into the oceans and some of these, such as noise due to seismic exploration for oil and gas and disturbance from marine traffic, may pose a threat to whale and dolphin populations.

Conservation of this species

Current action
Minke whales are included in the UK Grouped Species Action Plan for baleen whales which was published in 1999.

  • They are protected under Schedule 5 in the Wildlife (Northern Ireland) Order 1985.

Proposed objectives/actions

  • Maintain the current range of the minke whale

  • Maintain the current abundance of the minke whale.

What you can do
To report minke whale sightings contact CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU, Tel: 028 9039 5264, cedar.info [at] nmni.com.

Further information

Links
UK Biodiversity Action Plan

IWC

Irish Whale and Dolphin Group

Northern Ireland's Mammals, Amphibians & Reptiles

ARKive – Minke Whale

Wildlife and the Law

Literature

Text written by:
Angela Ross, Curator of Vertebrates, Ulster Museum

iNaturalist: Species account : iNaturalist World Species Observations database