Blue whiting

Scientific: Micromesistius poutassou. English: Blue whiting, poutassou. Icelandic: Kolmunni. For more languages see the Marine Animal Dictionary.

Biology and distribution

The blue whiting is a rather small codfish, usually 22 to 30 cm long, but can reach up to 50 cm in length. It is unique among codfishes since it is purely an open ocean pelagic fish. It can be found all around Iceland but occurs only sporadically off the north and northwest coast. It is found in European waters from Murmansk in the north to the Mediterranean Sea in the south but also around the Faroe Islands, in Greenlandic waters and, in small amounts, off North America. A related species, Micromesistius australis, lives in the Southern hemisphere.

The blue whiting is a true international fish. It is uncertain if there exists a stock of pure Icelandic strain. Most of the fish in Icelandic waters probably originate from larvae drift from the main spawning grounds off the British Isles or by the migration of adults. The adult stock migrates all over the eastern North Atlantic, up to the Barents Sea and even to the Denmark Strait. Mature blue whiting is found in the open sea, most often near the surface or in mid water, but can also be found down to depths of 1,000 meters. Migrations are irregular and probably controlled by ocean currents and temperatures. The blue whiting is a species that is either there in plenty or completely absent. For example, in 2003 large amounts occurred in the offshore shrimp survey off the entire northern Icelandic shelf. But apart from that, the blue whiting has been virtually absent in these surveys.

The blue whiting feeds on a variety of pelagic organisms, small fishes, small squid, copepods and krill.

Some limited spawning seems to occur in Icelandic waters but the main spawning grounds are to the north and northwest of the British Isles, close to the bottom at depths of 250 to 450 metres., Spawning takes place in February to March in the main spawning grounds, but earlier in warmer waters to the south and later in colder waters to the north. Upon spawning, the fish migrate north to feed and are found in greatest quantities between Iceland and Norway.

The blue whiting grows rapidly during its first year, and reaches maturity at the age of 2 to 4 years. After that growth slows down. It can reach up to 20 years of age and at seven years old it is about 32 cm long.

Catch and fishing methods

Blue whiting is among the ten most fished species in the world. The stock is very large and primarily fished in the northeast Atlantic. Large-scale fishing of blue whiting was resumed in Iceland in 1998 after almost two decades of very little fishing effort. In the past few years, fishing has increased very significantly, and in 2003 Icelandic vessels fished over 500,000 tonnes. Recently, landings by Icelandic vessels have declined considerably in phase with a declining stock.

Icelandic vessels originally fished chiefly within the Icelandic EEZ and in Faroese waters but have been seeking more distant watrers lately. The blue whiting fishing season starts in March with the best fishing in May-July. Fishing is exclusively by pelagic trawl. Usually, the fisheries are clean but occasionally saithe and redfish are caught as bycatch.

Blue whiting is fished by Norway, the Faroe Islands, Iceland and the EU. Towards the end of 2005, these parties agreed on the allocation of fishing quotas and the total allowable catch. This agreement also involved a systematic lowering of the TAC lately, to reduce fishing mortality.

Stock status (from the Marine Research institute)

International landings of blue whiting (Micromesistius poutassou) in the Northeast Atlantic in 2010 are estimated to be around 540 000 t. Icelandic landings were 88 000 t.

Results from an acoustic survey in the spawning area west of the British Isles in spring 2011 showed about 45% higher biomass than in 2010. The analytical assessment in 2010 indicates a steady decrease in the spawning stock of about 80% between 2003 and 2010. ICES will assess the stock in September and release its advice for 2012 in October 2011.

Processing and markets

More than 95% of the catch is reduced to fish meal. However, a small share is frozen at sea for human consumption. Half the export is to Norway where it is primarily used as feed in aquaculture.

Herring, capelin, blue whiting and recetly mackerel are the most valuable pelagic resources in Iceland. Blue whiting, however, belongs to the cod family and is low in lipids and light in colour, unlike the flesh of the others. Blue whiting is therefore well suited to processing but the raw material has a short storage life. When frozen at sea the blue whiting is therefore processed whole on board large freezer vessels.

References and further information

References: (Pálsson, 2005), (Jónsson & Pálsson, 2006).

For full citation and further information on the main species in general see this page

Hreiðar Þór Valtýsson, University of Akureyri