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Sole, Dover sole, Common sole

Solea solea

Method of production - Caught at sea
Capture method - Pulse trawl
Capture area - North East Atlantic (FAO 27)
Stock area - North Sea
Stock detail -
Certification - None
Fish type - White flat fish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is the least sustainable fish to eat and should be avoided. Click on the rating icon above to read more and on the alternatives tab below to find sustainable fish to eat.


Sustainability overview

The sole stock in this area is classified as healthy and fishing mortality is at a sustainable level, however the large scale use of electro pulse trawling in the southern North Sea without a better understanding of the ecological impacts of this experimental fishing method is concerning. Approximately 90 pulse trawlers are operating in the region yet further research is needed to establish the longer term impacts that exposure to electric pulse may have on target and non-target species and populations. Additionally, sufficient regulation is not in place to prevent the introduction of potentially damaging pulse systems. Until such research is complete and the fishery is better regulated, MCS recommends avoiding seafood from pulse trawl fisheries.

Please see the 'Capture info' TAB for more info about pulse trawling.

Biology

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.

Stock information

Stock area
North Sea

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Stock information
The spawning-stock biomass (SSB) has increased since 2007 and has been estimated at above MSY Btrigger since 2012. Fishing mortality (F) has declined since 1997 and is estimated to be at FMSY in 2015. Recruitment (R) has fluctuated without trend since the early 1990s.
ICES advises that catches in 2017 should be no more than 15 251 tonnes.

Management

No specific management objectives are known to ICES, there is no management plan for sole in the area.

Capture information

Pulse trawling in the North Sea is an experimental type of beam trawling which uses electrical pulses to shock and immobilise fish, making it easy for them to be captured in the trailing trawl net as opposed to traditional heavy tickler chains used to startle the fish. The use of electricity in the marine environment is generally forbidden under European Union law, but a series of derogations have been granted allowing the experimental use of pulse trawling in the southern North Sea, primarily to the Dutch fleet. In 2016 there were approximately 90 active pulse trawl vessels mainly targeting flatfish.

The method uses up to 50% less fuel than traditional beam trawling and there is evidence that it can reduce unwanted catches and physical disturbance to the sea floor, yet there is a lack of knowledge on whether the electric pulses can negatively impact on other species found near the seafloor and the ecological processes of the seafloor community, and concern has been raised over the widespread use of the gear before more comprehensive research has been undertaken. ICES have indicated that the current scale of use is above what would normally be associated with scientific research and that any expansion outside of what is currently permitted without a comprehensive environmental impact assessment would not be considered precautionary.

Research indicates that electric pulse trawling can cause spinal fractures and haemorrhaging in cod and whiting (mainly in larger fish) and can increase the vulnerability of shrimp to viral infection. Initial research on impacts to dab, dogfish and sole suggest there is little impact on these species. Laboratory experiments have investigated behavioural responses from a range of other seafloor species likely encountered by pulse trawling including a collection of molluscs, echinoderms, crustaceans and polychaetes. Whilst several species have not shown any significant behavioural difference to electric pulses, the green crab has shown a change in feeding behaviour and reduced survivability has been observed in a few species. ICES states that there is no reason to assume that the effects of electrical stimulation on invertebrates has a larger impact than that from conventional beam trawling yet note that research questions remain for target and non-target species regarding delayed mortality and long-term population effects as well as sub-lethal and reproductive effects of electric trawls. ICES also considers that the existing regulatory framework is not sufficient to prevent the introduction of potentially damaging pulse systems.

A four-year scientific research programme has recently been commissioned by the Dutch government which aims to answer many of these remaining questions.

Read more about capture methods

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below . Click on a name to show the sustainable options available.

Dab Depending on how and where it's caught this species ranges from sustainable to unsustainable. Click the name to display only the sustainable options.

Flounder Depending on how and where it's caught this species ranges from sustainable to unsustainable. Click the name to display only the sustainable options.

Halibut, Atlantic (Farmed) Depending on how and where it's caught this species ranges from sustainable to unsustainable. Click the name to display only the sustainable options.

Halibut, Pacific

Sole, Dover sole, Common sole Depending on how and where it's caught this species ranges from sustainable to unsustainable. Click the name to display only the sustainable options.

Turbot (Farmed)


References
ICES, 2016. Advice book 6. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2016/2016/sol-nsea.pdf [Accessed July 2016].

ICES, 2016. Request from France for updated advice on the ecosystem effects of pulse trawl. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2016/Special_Requests/France_Effects_of_pulse_trawl.pdf [Accessed Aug 2016].

NSAC, 2015. Advice on the: Use of pulse trawls in the North Sea. Available at http://www.nsrac.org/wp-content/uploads/2014/12/7-1415-20150923-Use-of-Pulse-Trawls-in-the-North-Sea.pdf [Accessed August 2016].

Soetaert, M., Decostere, A., Polet, H., Verschueren, B., Chiers, K., 2015. Electrotrawling: a promising alternative fishing technique warranting further exploration. Fish Fish, 16: 104-124. doi:10.1111/faf.12047. Available at http://onlinelibrary.wiley.com/doi/10.1111/faf.12047/full [Accessed Sept 2016].

Van Marlen, B., de Haan, D., Van Gool, A. and Burggraaf, D., 2009. The effect of pulse stimulation on marine biota - Research in relation to ICES advice - Progress report on the effects on benthic invertebrates, IMARES C103/09, 53 pp.

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