Witch flounder

Scientific: Glyptocephalus cynoglossus. English: Witch flounder, witch, gray sole. Icelandic: Langlúra, vitsi. For more languages see the Marine Animal Dictionary.

Biology and distribution

The witch flounder is a medium sized, rather long and thin flatfish, usually around 30 cm long, but the largest individual caught in Icelandic waters measured at 66 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 mud or sand bottoms at depths between 50 to 300 m. It is found in European waters from Murmansk in the north to the Bay of Biscay in the south. It also inhabits seas around the Faroe Islands, in Greenlandic waters and from Labrador to Cape Cod in North America.

Witch flounder 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 April 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. The distribution and biology of the witch flounder is remarkably similar as for lemon sole except that they prefer somewhat different bottom types.

Catch and fishing gear

Until the 1970s, foreign fleets have dominated catches of witch flounder off Iceland, mainly boats from England and Germany, and later by Scottish and Belgian vessels. After the ITQ system was established in groundfish fisheries in 1984 and the effort for the most important groundfish species was reduced, Icelandic fishermen started to look at alternative species, and the catching of witch flounders increased sharply. This ascent was very rapid in the beginning; from 32 t in 1985, to a peak of 4,566 in 1987. Catches then fell, and there were worries that the witch was being overfished. However, stock has grown considerably in recent years and catches are now around 2,000 tonnes. Most of the current catches are by the Danish seine fleet but also, to some extent, by lobster and groundfish trawl. Witch flounder catches are rather evenly spread over the year. Special witch seines with 120 mm mesh size (as opposed to 135 mm normally) in the cod end are permitted from September to April. The main fishing grounds are off the south and southwest coast.

Stock status (from the Marine Research institute)

Since 1988, landings of witch (Glyptocephalus cynoglossus) have been between 1 000 and 3 000 t, with landings in 2010 amounting to 1 300 t.

The abundance index for the fishable stock (larger than 30 cm) more than tripled from 1997 to 2005, but has since been declining. The size of the witch stock remains uncertain, but all data indicate that both the fishable stock and recruitment have declined in recent years. The MRI recommends a TAC of 1 100 t for the quota year 2011/2012.

Processing and markets

Most of the witch flounder catch is iced at sea and then processed and frozen after landing.

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