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

4.b, c


Picture of Sole, Dover sole, Common sole

Sustainability rating five info

Sustainability overview

The stock assessment in 2018 indicated the biomass of common sole in the North Sea was healthy yet fishing mortality a little above the level associated with the Maximum Sustainable Yield (FMSY). 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 large pulse trawlers are operating in the region under experimental derogations to an EU ban. A recent review from the International Council for the Exploration of the Sea (ICES) suggests that pulse trawling likely has fewer environmental impacts than traditional beam trawling due to less physical disturbance of the gear. However, there remain several outstanding issues of concern in relation to non-physical impacts, such as delayed mortality and long-term population effects as well as sub-lethal and reproductive effects of electric trawls. A four-year scientific research programme is expected to be completed in 2019 and whilst these uncertainties remain, MCS does not believe the scale of pulse trawling reflects precautionary management and applies a critical fail to this capture method as a result.

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

Criterion score: Default red rating info

Stock Area

North Sea

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 1999 and is close to FMSY in 2017. Recruitment (R) has fluctuated without trend since the early 1990s, but without the large year classes that occurred in the preceding period.
ICES assesses that fishing pressure on the stock is above FMSY but within the EU Multiannual Plan (MAP) range and below Fpa and Flim; and spawning-stock size is above MSY Btrigger, BMGT, Bpa, and Blim.
ICES advises that when the proposed MAP for the North Sea is applied, catches in 2019 should be between 7451 tonnes and 21 644 tonnes, but according to the MAP, catches higher than those corresponding to FMSY (12 801 tonnes) can only be taken under certain conditions.

Management

Criterion score: Default red rating info

The EU adopted a management plan for flatfish in the North Sea in June 2007 which has been evaluated by ICES as precautionary. The EU is finalising a multi-annual plan for the North Sea. According to the MAP, catches higher than those corresponding to FMSY (12 801 tonnes) can only be taken under conditions specified in the MAP.

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

Capture Information

Criterion score: Default red rating info

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, primarily to the Dutch fleet, allowing the experimental use of pulse trawling in the southern North Sea. 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 (2016) stated 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. More recently, ICES have suggested that pulse trawling likely has fewer environmental impacts than traditional beam trawling due to less physical disturbance of the gear, however, there remain several outstanding issues of concern in relation to non-physical impacts, such as delayed mortality and long-term population effects as well as sub-lethal and reproductive effects of electric trawls. A four-year scientific research programme is expected to be completed in 2019 and whilst these uncertainties remain, MCS does not believe the current scale of pulse trawling is justified and does not reflect precautionary management. A critical fail to this capture method currently applies resulting in a default red rating.

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
Halibut, Atlantic (Farmed)
Halibut, Pacific
Megrim
Plaice
Sole, Dover sole, Common sole
Sole, Lemon
Turbot (Caught at sea)
Turbot (Farmed)

References

ICES, 2018. The Netherlands request on the comparison of the ecological and environmental effects of pulse trawls and traditional beam trawls when exploiting the North Sea sole TAC. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/Special_requests/nl.2018.08.pdf [Accessed Sept 2018].

ICES, 2018. Sole (Solea solea) in Subarea 4 (North Sea). Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/sol.27.4.pdf [Accessed Sept 2018].

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 , 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.