Sole, Dover sole, Common sole
Method of production - Caught at sea
Capture method - Gill or fixed net
Capture area - North East Atlantic (FAO 27)
Stock area - North Sea
Stock detail - IV
Certification - Marine Stewardship Council (MSC)
Fish type - White flat fish
The Hastings Fleet Dover sole fishery and the Cooperative Fishery Organisation (CVO) North Sea plaice and sole fishery were certified by the Marine Stewardship Council (MSC) as environmentally responsible or sustainable fisheries in July 2009 and December 2012 respectively. Avoid eating immature sole (less than 30cm) and fresh (not previously frozen) fish caught during the breeding season (April-June).
Sole is a right-eyed flatfish (eyes on the right hand side of the body) and belongs to the family of flatfishes known as Soleidae. It spawns in spring and early summer in shallow coastal water, from April to June in the southern North Sea, from May-June off the coast of Ireland and southern England, and as early as February in the Mediterranean. Common sole become sexually mature at 3-5 years, when 25-35cm long, the males being somewhat smaller than the females. It can attain lengths of 60-70cm and weigh 3kg.The maximum reported age is 26 years. Sole is a nocturnal predator and therefore more susceptible to capture by fisheries at night than in daylight.
Spawning stock biomass (SSB) for the North Sea sole stock has been increasing since 2007 and is estimated to now be above MSY Btrigger in 2015. Fishing mortality has shown a declining trend since 1995 and is estimated to be above FMSY in 2014. ICES advises catches in 2016 should be no more than 12,835 tonnes. If discard rates (10-20%) do not change this implies landings of no more than 11,921 tonnes (10,973t in 2015; 11,900 t in 2014; 14,000 t in 2013).
The EU adopted a management plan for flatfish in the North Sea in June 2007 and it is considered by ICES, with a high probability, that this will prevent the stock dropping below safe biological limits in the next decade. The plan has been evaluated by ICES as precautionary.
Gillnets can be very size selective for the target fish but can be unselective at the species level for both non-target fish and for mammals, birds and turtles. Harbour porpoise are highly prone to bycatch in bottom-set gillnets used to catch demersal species such as cod, turbot, hake, saithe, sole, skate and dogfish and tangle net fisheries used to capture flat fish and crustaceans, due largely to their feeding habits on or near the seabed. Porpoises are generally taken as single animals. The number taken ranges from 1 in 20 hauls for skate to 1 in 54 hauls for cod. High levels of Harbour porpoise bycatch have been recorded in the Celtic and North Sea. In areas where population levels of cetaceans are very low, such as the Baltic and the southern North Sea/Eastern Channel, even a very low level of bycatch is extremely serious in conservation terms. EU Regulation 821/2004 requires all community fishing vessels, greater than or equal to 12 metres, using drift, gill and tangle nets to use pingers - acoustic devices to deter marine mammal entanglement in nets. It also requires Member States to introduce observer schemes to monitor cetacean bycatch in certain fisheries, most notably in pelagic trawls, and the phase out of driftnet fisheries in the Baltic Sea. However, despite the pinger requirement coming into force in June 2005 in the North Sea, January 2006 in the Western Channel and January 2007 in the Eastern Channel, the UK fleet (along with the majority of European vessels) is still not applying this provision. The reason given is that the pingers available present too many practical and health and safety problems. This means that in the UK there are still no mitigation measures in place to reduce what is likely to remain the main conservation and welfare problem affecting cetaceans around our coasts. Other measures that maybe adopted to reduce the number of marine mammal casualities include reducing the length of the net and soak time, i.e. the period of time the net is in the sea. Because of their durability, nets are made of nylon; if lost the net can continue to fish, a phenomenon known as 'ghost fishing'. Avoid eating immature sole (less than 30cm) and fresh (not previously frozen) fish caught during the breeding season (April-June).
The Net Effect. A WDCS Report for Greenpeace. Ross and Isaac (2004); The Price of Fish: A review of cetacean bycatch in fisheries in the north-east Atantic. L Nunny (2011); ICES Advice 2015, Book 6 http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2015/2015/sol-nsea.pdf
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