Lemon sole

Scientific: Microstomus kitt. English: Lemon sole, lemon. Icelandic: Þykkvalúra, sólkoli. For more languages see the Marine Animal Dictionary.

Biology and distribution

The lemon sole is a medium sized rather thickset flatfish, usually around 30 cm long, but the largest individual caught in Icelandic waters measured at 63 cm. It is found all around Iceland, but is much rarer in the colder waters north and east of the country. Mostly it occurs on rocky or sandy bottoms at depths between 50 to 350 m. It is found in European waters from Murmansk in the north to the Bay of Biscay in the south. Also around the Faroe Islands, in Greenlandic waters and from Labrador to Cape cod in North America.

Lemon sole feeds primarily on polychaetes, but also to a lesser extent on other groups such as sandeels. Its small mouth however restricts its feeding range. Spawning takes place along the south and southwest coasts, in March to June. Growth is rather slow, but females grow faster than males. Most of the males are sexually mature at 5, and females at 7. In Icelandic waters, the lemon sole can reach 14 years of age.

Catch and fishing gear

Per unit weight, the lemon sole is among the most valuable species in Icelandic waters. After halibut (which is still more valuable) and plaice (which is much more abundant), lemon sole was the most sought after flatfish by foreign fleets in Icelandic waters. These catches peaked at 3,000 tonnes in 1937. Catches fell again during WWII, but increased again shortly after the war. Catches then started to drop when Icelanders gradually extended their EEZ. Originally catches were almost exclusively by English and German boats, but after the Second World War by English and Icelandic vessels. Lemon sole has not been a very important fish in Icelandic fisheries and has usually been a bycatch. During the period from 1974 to 1984 catches were very low, but increased rapidly after 1985 and have been quite high in recent years. Roughly half of the catch is by Danish seine, the rest mainly by bottom trawl and to a lesser degree lobster trawl.

Stock status (from the Marine Research institute)

In 2010, 2 000 t of lemon sole (Microstomus kitt) were landed. Indices of fishable stock from the groundfish survey have been high in recent years and recruitment indices have also been high since the early 2000s. CPUE in the Danish seine fishery off southwest Iceland has doubled from the period 1993–1998 to the present. Preliminary stock assessment indicates a very high fishing mortality rate. Therefore, the MRI recommends the effort to be reduced and a TAC no higher than 1 800 t for the quota year 2011/2012.

Processing and markets

The majority of the catch is exported fresh in containers or by air, as is common with valuable species. A large part is also processed and frozen after landing and a share is also frozen at sea. Almost all the exports of lemon sole are to the United Kingdom.

References and further information

References: (Steinarsson, 1979), (Jónsson & Pálsson, 2006).

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

Hreiðar Þór Valtýsson, University of Akureyri