Baleen whales

Baleen whales are the largest animals on earth, and they are quite common around Iceland. The common minke and fin whales are the most abundant species but sei and humpback whales are also common. The blue whale used to be abundant but numbers are now low due to overexploitation in the past. These species form a taxonomically related group within the baleen whales called rorquals.

Three other baleen whale species have occurred in Icelandic waters, none of them is a rorqual. Bowhead whales (Balaena mysticetus) are rare guests from the north, associated with very cold years and sea ice. This species was last seen in Icelandic waters a long time ago, in 1879. Its close cousin the Northern right whale (Eubalaena glacialis) is now a rare guest from the south. It is almost certain that this species was much more common in Icelandic waters in the past. However, the right whales were the first large whales to be hunted as they are fat (give a lot of valuable oil and float when dead) and slow. Right whales in the North Atlantic were therefore hunted close to extinction several centuries ago and still have a long way to recover. Only a few individuals have been sighted since regular whale surveys began in Icelandic waters in 1987. The third baleen whale species that has been found in Icelandic waters is the grey whale (Eschrictus robustus). This was, however, a long time ago as grey whales went extinct in the North Atlantic Ocean in the 17th or 18th century. It is still a mystery why this happened as there are actually very few records of this species being hunted.

Blue whale (Balaenoptera musculus)

Blue whale Illustration: Jón Baldur Hlíðberg

The blue whale is the largest animal on earth, probably ever. The largest individual measured 33.5 m long and the record weight is 190 t. However, these individuals were from Antarctic waters. In the northern hemisphere blue whales tend to be smaller. The blue whale is truly a global species, but it usually migrates between colder feeding areas in summer and warmer breeding areas in winter. Unlike sei and fin whales, which are predominantly offshore species in Icelandic waters, the blue whale can be seen both inshore and offshore. The blue whale occurs all around Iceland but is most common off the western part. It feeds almost exclusively on planktonic crustaceans, mostly krill.

Blue whales were a large part of the whale catch in Icelandic waters prior to the first moratorium on whaling in 1916. At the beginning of the industrial whaling in Icelandic waters, they were the most preferred catch as they were the largest. However, by 1900 their numbers had declined considerably due to hunting, and fin whales became the most sought after species. During this period a total of 6,500 blue whales were killed, mostly off the Vestfirðir peninsula. In the later whaling period after 1948 only 163 animals were killed. Hunting of the blue whale was banned in Icelandic waters in 1960. It is quite obvious that the blue whale was overexploited all over the world during the industrial whaling period. The Icelandic stock is now estimated to be between 1,000 and 1,500 animals and still has a long way to go to reach its earlier size. However, on a positive note, the stock has been growing at a 5% rate in recent decades.

Sei whale (Balaenoptera borealis)

Sei whale Illustration: Jón Baldur Hlíðberg

The sei whale is between the fin and common minke whales in size. It is quite a large animal and can reach up to 21 m in length and weigh 30 t. The average size is 14 m and 20 t. Although the species is relatively common in Icelandic waters, it does prefer warmer waters than the other rorquals. As Icelandic waters are in the northern region of its range, it is primarily found in the warmer waters south and west of Iceland. The migrations are less predictable than for example those of the fin whale and consequently the sighting numbers can vary substantially between years. The sei whale also arrives later in Icelandic waters than the fin whale, but leaves later in the autumn. Like the other rorquals, the sei whale has a global distribution

Globally the diet of the sei whale is quite variable. In some areas small fishes or squid are the bulk of the food, while planktonic crustaceans (copepods and krill) are the main food in others. In Icelandic waters they seem to feed predominantly on planktonic crustaceans.

After the Second World War, the sei whale was the second most important species targeted by the Icelandic whaling fleet, after the fin whale. About 2500 animals were hunted between 1952 and 1985, when a moratorium was established. Catches prior to that were quite low because of the relative small size of the whale compared to the blue and fin whales. A similar pattern occurred in the southern oceans where the sei whales were only hunted after the other species had been decimated. Sighting surveys have indicated a minimum population size of 10,500 animals in Icelandic and adjacent waters. The stock is considered to be large enough to sustain some catches.

Humpback whale (Megaptera novaeangliae)

Humpback whale Illustration: Jón Baldur Hlíðberg

The humpback whale is closely related to the other rorqual species of the genus Balaenoptera but is still different enough to have its own genus, Megaptera, meaning "giant wings". This refers to one of the main identification features, the huge flippers. The humpback whale is also much stockier than the other rorquals and has a characteristic warty nose. It can reach up to 17 m length and 40 t in weight, shorter but heavier than the sei whale. The feeding habits in Icelandic waters have not been studied but its distribution and some visual observations suggests that it is quite opportunistic, feeding equally on pelagic fishes and planktonic crustaceans.

Humpback whales have global distribution as the other rorquals. As the others rorquals, it migrates to warmer waters in winter, such as the Caribbean. However this is not without exceptions as some are known to stay in Icelandic waters during the winter. Humpbacks can be seen all around Iceland, both offshore and inshore. They are among the most popular whales for the whale watching industry as they are common inshore (where the other large whales are rarely seen), have quite predictable behaviour and are the most playful of the large whales.

Humpbacks were also quite popular with whalers in the past, as they were slow and fat compared to the other rorquals. Apart from the two right whale species, humpbacks were the most sought after species before the invention of the explosive harpoon and the steam engine. Whalers from many nations conducted their business around Iceland in previous centuries, pioneered by the Basques from Spain. It is, however, quite difficult to estimate the species composition and the numbers hunted. It is not unlikely that when mechanized whaling began around Iceland, shortly before the turn of the 20th century, the humpback stocks might already have been exploited to low levels in many areas. When the Norwegians established whaling factories in Iceland in 1889 and began hunting whales with modern equipment, about 2,800 humpbacks were hunted until the first moratorium on whaling in Icelandic waters in 1916. Only six individuals were caught after the Second World War and a moratorium on humpback whaling was established in 1955. At that time they had become very rare. The stock recovery was slow for a long time, as might be expected for a large and slow growing animal. The stock has, however, grown surprisingly fast lately, or up to 12% each year. Humpbacks have therefore recently become quite common in Icelandic waters to the pleasure of whale watchers and horrors of pelagic fishermen whom they compete with for food and sometimes destroy their fishing gear. Their number is now estimated to be around 14,000 individuals, which is probably close to historical maximum in Icelandic waters.

References and further information

• Stevick, P. T., Allen, J., Clapham, P. J., Friday, N., Katona, S. K., and Larsen, F. (2003). North Atlantic humpback whale abundance and rate of increase four decades after protection from whaling. Marine Ecology Progress Series 258, 263-273.
• Stevick, P. T., Allen, J., Clapham, P. J., Katona, S. K., Larsen, F., and Lien, J. (2006). Population spatial structuring on the feeding grounds in North Atlantic humpback whales (Megaptera novaeangliae). Journal of Zoology 240, 244-255.
• Víkingsson, G. A. (2004). Hnúfubakur (Humpback whale). In Hersteinsson, P. (ed.), Íslensk spendýr (Icelandic mammals) (pp. 224-229). Reykjavík, Iceland: Helgafell.
• Víkingsson, G. A. (2004). Steipireyður (Blue whale). In Hersteinsson, P. (ed.), Íslensk spendýr (Icelandic mammals) (pp. 200-203). Reykjavík, Iceland: Helgafell.
• Víkingsson, G. A. (2004). Sléttbakur (right whale). In Hersteinsson, P. (ed.), Íslensk spendýr (Icelandic mammals) (pp. 194-197). Reykjavík, Iceland: Helgafell.
• Víkingsson, G. A. (2004). Sandreyður (Sei whale). In Hersteinsson, P. (ed.), Íslensk spendýr (Icelandic mammals) (pp. 212-217). Reykjavík, Iceland: Helgafell.
• Víkingsson, G. A. (2004). Sandlægja (Grey whale). In Hersteinsson, P. (ed.), Íslensk spendýr (Icelandic mammals) (pp. 198-199). Reykjavík, Iceland: Helgafell.
• Víkingsson, G. A. (2004). Norðhvalur (Greenland whale). In Hersteinsson, P. (ed.), Íslensk spendýr (Icelandic mammals) (pp. 192-193). Reykjavík, Iceland: Helgafell.

Hreiðar Þór Valtýsson, University of Akureyri