Turbot (Caught at sea)
Capture method — Beam trawl
Capture area — North East Atlantic (FAO 27)
Stock area — North Sea
Stock detail — 4
Updated: July 2019.
The latest stock assessment indicates that turbot in this region is not subject to overfishing or in an overfished state, with fishing mortality and the spawning biomass being below and above respective MSY reference points. Despite this, catches consist predominantly of immature fish, which is having a negative impact on the potential yield from the stock. As turbot is a fast-growing species, reduction in the exploitation on younger ages would lead to an increase in maximum sustainable yield, supporting the need to reduce catching turbot under its length at maturity of between 30 and 35cm for males and females respectively. Management of turbot and brill is under a combined species Total Allowable Catch (TAC) which prevents effective control of the single-species exploitation rates and could lead to high grading of the lower value species (brill) or overexploitation of turbot. Catches in the last two years have been in line with the scientific advice, but it was exceeded in the two years previous. Beam trawls can encounter relatively high levels of bycatch including demersal elasmobranchs and occasionally protected, endangered and threatened (PET) species (e.g. sharks and rays). Beam trawlers interact with the seabed and can modify bottom topography and cause damage and removal of some biogenic features including vulnerable marine habitats and benthic communities.
Turbot belongs to a small family of left-eyed flatfish (both eyes on the left of the body), known collectively as the Scophthalmidae. This family of fish is confined to the north Atlantic basin and includes megrim and brill. Turbot becomes sexually mature at an age of 3-5 years and in most parts of its range spawns in April to August, females each producing up to 10-15 million eggs. Turbot is one of the fastest growing flatfish, with females growing faster than males, in the North Sea reaching a length of around 30 cm (males) and 35 cm (females) in about 3 years. In the Baltic Sea growth is slower, and the males become sexually mature at a length of 15 cm, the females at 20 cm. By 10 years of age growth rates have reduced to 1-2 cm per year for females and less than 1 cm per year for males. Consequently, females are larger than males at any given age. Turbot can attain a length of 1m and a weight of 25 kg. Maximum reported age 25 years. For some reason males are generally more abundant than females. Turbot is distributed from Iceland, down the coast of western Europe and into the Mediterranean. Turbot are typically found at a depth range of 10 to 70 m, on sandy, rocky or mixed bottoms. It is one of the few marine fish species that inhabits brackish waters. Turbot appears to be a rather sedentary species, although some adult migration may occur.
Criterion score: 0 info
The latest stock assessment was undertaken in 2019 and indicated that turbot in this region is not subject to overfishing or in an overfished state, with fishing mortality and the spawning biomass being below and above respective MSY reference points. Despite this, catches consist predominantly of immature fish, which is having a negative impact on the potential yield from the stock. As turbot is a fast-growing species, reduction in the exploitation on younger ages would lead to an increase in maximum sustainable yield, supporting the need to reduce catching turbot under its length at maturity of between 30 and 35cm for males and females respectively.
At request of the European Commission, ICES have provided advice based on their precautionary approach despite data and advice relating to maximum sustainable yield (MSY) being available. ICES advises that catches of up to 4538 tonnes are considered to be precautionary, but the assessment outlines that this would result in a reduction in biomass by 9.4%. In contrast, a catch at the MSY rate of 3649tonnes would maintain the stock biomass at its current healthy level. The 2018 catch was 3626 tonnes and previous five year average was 3549 tonnes.
ICES note that a fisheries-independent survey, having both adequate catchability of large flatfish and covering the entire distribution area of the stock, is needed to improve the assessment. To address this issue in future assessments, a Dutch science-industry partnership initiated a new fisheries-independent beam trawl survey for turbot and brill in 2019.
Criterion score: 0.75 info
Management of turbot in the North Sea requires considerable improvement. Turbot is a high value bycatch species in fisheries for plaice and sole and is classed as a bycatch species under the EU North Sea Multiannual Management Plan (NSMAP) for demersal stocks which came into effect in 2018. The NSMAP aims to ensure that exploitation of living marine biological resources restores and maintains populations of harvested species above levels which can produce the Maximum Sustainable Yield (MSY) and that the precautionary approach to fisheries management is applied. Bycatch stocks do not have specific targets under the NSMAP but are supposed to be managed in accordance with the best available scientific advice and the precautionary approach when no adequate scientific information is available. However, MCS has concerns that the NSMAP is not being adhered to for all bycatch stocks, especially where adequate scientific advice is available, as is the case with turbot. This has resulted in catch advice for turbot being considerably higher and well above MSY which, if followed, is expected to reduce the biomass.
Turbot in this area is managed under a combined total allowable catch (TAC) together with brill. ICES have indicated that management of brill and turbot under a combined species TAC prevents effective control of the single-species exploitation rates which can result in high-grading and discarding of the lesser value species and overexploitation of the high value one, turbot. The total catches of turbot have been within the scientifically recommended levels the last two years, but substantially exceeded them in the two before those.
Catches consist predominantly of immature fish, which is having a negative impact on the potential yield from the stock. As turbot is a fast-growing species, reduction in the exploitation on younger ages would lead to an increase in maximum sustainable yield, supporting the need to reduce catching turbot under its length at maturity of between 30 and 35cm for males and females respectively. There is no official EU minimum conservation reference size (MCRS) for brill, although some regional authorities have applied their own. The most frequently applied is 30cm (e.g. in Belgium, Baltic, Cornwall), although even this size could be considered too small as brill do not mature until 33 -40cm for males and females respectively.
ICES note that a fisheries-independent survey, having both adequate catchability of large flatfish and covering the entire distribution area of the stock, is needed to improve the assessment. To address this issue in future assessments, a Dutch science-industry partnership initiated a new fisheries-independent beam trawl survey for turbot and brill in 2019
Turbot has been under the landing obligation since the start of 2019 without exemptions.
Surveillance activities on fisheries for demersal stocks in the North Sea, Skagerrak and Kattegat and English Channel include the use of vessel monitoring systems (VMS) on vessels over 12m; direct observation by patrol vessels and aerial patrols; inspections of vessels, gear, catches at sea and on shore and requirements to record data in electronic logbooks (although vessels under 10m do not have to keep logbooks).
Criterion score: 0.75 info
Turbot is a valuable bycatch species in beam (67%) and otter trawl (25%) and gillnet and trap (8%) fisheries for flatfish (plaice and sole) and other demersal species. Quota restrictions apply only to the North Sea, where around 90% of the catches in the Northeast Atlantic are taken.
Beam trawls have the potential to take relatively high quantities of bycatch (> 50% of catch weight) including sharks, skates and rays and occasionally protected, endangered and threatened (PET) species.
Beam trawls disturb seabed habitats and in the North Sea, beam trawlers have reduced the biomass and production of bottom-dwelling organisms. Sustained fishing within the core areas for this fishery are in relatively shallow areas of fine sand and sandy mud which are heavily fished. This has resulted in a shift from communities dominated by relatively sessile, emergent and high biomass species to communities dominated by infaunal, smaller bodied and faster growing organisms. The penetration depth of a beam trawl depends on sediment characteristics and varies between 1 cm and 8 cm. Trawls leave detectable marks on the seabed and the pressure exerted on the sea floor is strongly related to the towing speed, which is very high in flatfish fisheries as the gear itself is very heavy. The habitat risks are related to the types of seabed communities and other sources of seabed disturbance such as wave and tidal action. Within the North Sea, one of the more sensitive habitats that may be impacted by beam trawl is slow growing Sabellaria reef, frequently found in shallower areas of the southern North Sea. Further north, the large and very long-lived bivalve Arctica islandica (Ocean quahog), can also suffer damage in trawls. Some spatial management is in place but there remains a need to implement management measures in many designated marine protected areas to allow for the protection and recovery of these areas and sensitive designated features.
There are MPAs designated to protect seabed features from damaging activities in this region. The fishery overlaps with parts of these MPAs, but the proportion of the catch coming from these areas is expected to be relatively low in relation to the unit of assessment (i.e. less than 20% of the catch) and so these impacts have not been assessed within the scale of this rating. Given the important role that MPAs have in recovering the health and function of our seas, MCS encourages the supply chain to identify if their specific sources are being caught from within MPAs. If sources are suspected of coming from within designated and managed MPAs, MCS advises businesses to: establish if the fishing activity is operating legally inside a designated and managed MPA; and to request evidence from the fishery or managing authority to demonstrate that the activity is not damaging to protected features or a threat to the conservation objectives of the site[s].
The overall capacity and effort of the North Sea beam trawl fleet has been substantially reduced since 1995, likely due to a number of reasons, including effort limitations between 2008 and 2016 for the recovery of the cod stock. Fishing effort of the beam trawl fleet has shifted towards the southern North Sea to target sole over the past decade.
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)
Sole, Dover sole, Common sole
Turbot (Caught at sea)
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Lakkeborg, S. 2005. Impacts of trawling and scallop dredging on benthic habitats and communities. FAO Fisheries Technical Paper. No. 472. Rome, FAO. 2005. 58p.
Tillin, H.M., Hiddink, J.G., Jennings, S. and Kaiser, M. J., 2006. Chronic bottom trawling alters the functional composition of benthic invertebrate communities on a sea-basin scale. Marine Ecology Progress Series. Vol. 318. 31-45.