Horse Mackerel, Scad

Trachurus trachurus

Method of production — Caught at sea
Capture method — Purse seine
Capture area — North East Atlantic (FAO 27)
Stock area — Norwegian Sea, North Sea (North), Celtic Seas, Cantabrian Sea, English Channel (South), Bay of Biscay. Western stock.
Stock detail — 8, 2a, 4a, 5b, 6a, 7a–c, 7e–k
Picture of Horse Mackerel, Scad

Sustainability rating four info

Sustainability overview

Updated: July 2020.

The Western horse mackerel stock is in a poor state and harvested unsustainably. There is no precautionary management plan in place for this stock. The fishery is managed by an annual Total Allowable Catch (TAC) limit, which has been consistent with scientific advice in recent years, but it has not always limited annual catch. Bycatch of Endangered, Threatened and Protected (ETP) species, and other non-target species have not been reported within this fishery. Habitat impacts from purse seine and pelagic trawling is deemed to be very low.


Horse mackerel or scad belongs to a group of fish known as Carangidae. Adults are pelagic and form large schools in coastal areas with sandy substrate, usually in depths of 100-200 m, but reported to 500 m. Often shoals with juvenile herring. The Atlantic horse mackerel can be found in the north-eastern Atlantic from Iceland to Senegal, including the Cape Verde islands, and also in the Mediterranean and the Black Sea. Can attain a maximum length of 70 cm, but more commonly 22cm, with a maximum published weight of 2 kg. Matures at a length of around 24 cm (range 21 to 30 cm). Spawning takes place in summer in the North Sea, and earlier to the south of Biscay. Scad horse mackerel are batch spawners. Females lay 140,000 eggs, which hatch into 5 mm long larvae. Eggs are pelagic. They feed on fish, crustaceans, and cephalopods.

Stock information

Criterion score: 0.75 info

The stock is in a poor state and fishing pressure is above sustainable levels.

The spawning-stock biomass (SSB) has shown a decreasing trend since 2006 and is below MSY Btrigger (1,168,272 tonnes); 2019. SSB has decreased >25% between 2006 and 2019, from 1,651,270 to 872,831 tonnes, respectively. SSB is just above its historical low (1982-2019) and close to the biomass limit (834,480 tonnes), where stock recruitment may be impaired (Blim). In 2019, the ratio of B:BMSY was 0.77.  Fishing mortality (F) (0.087) has decreased since 2013, but remains above the maximum sustainable yield (FMSY) (0.074), which it has been since 1992, due to lower catches and a reduced proportion of the adult population in the exploited stock. In 2018, the ratio of F:FMSY was 1.18. The development of the fishery was supported by an extraordinary high recruitment (R) level in the 1982-year class. The stock and the fishery are very dependent on occasional high recruitments. After a series of low recruitments, the estimates since 2014 are above average (1983–2018). Given the recent above-average recruitments, the stock is predicted to increase in 2020.

ICES advises that when the MSY approach is applied, catches in 2020 should be no more than 83,954 tonnes, a 42% decrease compared to last year’s advice (2019). The main reason for this reduction, is due to the downward revision of the biomass estimates and the update of reference points in the recent inter-benchmark in 2019.

Horse mackerel in the northeast Atlantic is considered to be separated into three stocks: the North Sea, the Southern and the Western stocks. The two stocks prevalent within and surrounding UK waters, are the Western and North Sea stocks. The Western stock spawns in the Bay of Biscay, UK and Irish waters in early spring, migrating to the Norwegian Sea and North Sea. The North Sea stock spawns in the southern North Sea in summer, migrating to central North Sea, Skagerrak and Kattegat. There is some overlap between the stocks and possible mixing, but this is undetermined. In 2015 the Pelagic Advisory Council and the EAPO Northern Pelagic Working Group, together with University College Dublin (Ireland), initiated a research project on the genetic composition of horse mackerel stocks. Genetic samples have been taken over the entire distribution area of horse mackerel during the years 2015, 2016, and 2017, with a specific focus on the separation between horse mackerel in the western waters and horse mackerel in the North Sea. A full genome sequencing exercise has been initiated to allow for future mixed-sample analyses.


Criterion score: 0.5 info

There are some management measures in place for this fishery, which are partly effective in managing the stock.

There are no horse mackerel management agreements between EU and non EU countries. To date, no agreed management plan is available for this stock despite several attempts to develop such management plans.

The industry, in conjunction with the Pelagic AC (PELAC), has been working actively on the development of a potential Harvest Control Rule (HCR) and rebuilding plan. The development of a rebuilding plan is at an advanced stage and a draft is expected to be available in 2020.

The European Union regulates the fishery by Total Allowable Catch (TAC). As the TAC is set by the EU, it therefore only applies to EU waters and the EU fleet in international waters. In Norwegian waters there is no quota for horse mackerel but existing regulations on bycatch proportions as well as a general discard prohibition (for all species) apply to horse mackerel. The TAC is set in accordance with the distribution of the stock, since 2011, although catches in Division 3a are taken outside the TAC as the TAC has only been given for parts of the distribution and fishing areas (EU waters). It is advised that the TAC should apply to all areas where western horse mackerel are caught. If the management area limits are revised, measures should be taken to ensure that misreporting of juvenile catch taken in Divisions 7e, 7h and 7d (the latter then belonging to the North Sea stock management area) is effectively hindered. The mismatch between TAC and fishing areas and the fact that the TAC is only applied to EU waters has resulted in the catch prior to 2007 exceeding those advised by ICES.

Over the last 5 years, TACs have mostly been set in line with scientific advice; 2015-2019. However, in 2017 the agreed TAC was 38% above advice. Catches are generally in line with advice, but catch exceeded advice in 2014 and 2017, by 23% and 20%, respectively. Compliance with TAC is high, with the total annual catch being on average 92% of the TAC; 2014-2018. Although, the TAC has not limited catches in recent years; 2016, 2017, and 2018.

Overall discarding is considered negligible; 3% in 2018.

Beyond TACs the fishery is managed by an EU minimum landing size of 15 cm for horse mackerel, which is significantly smaller than the length of maturity for the species. Length at first maturity is between 16 and 27 cm, but most commonly 21 cm. Consequently, horse mackerel are caught before they have had chance to reproduce (10% undersized allowed in the catches).

Considering the potential of mixing between Western and North Sea horse mackerel occurring in Division 7d and 7e, better insight into the origin of catches from that area will be a major benefit for improvement of the quality of future scientific advice and thus management of the North Sea and Western horse mackerel stocks. A project addressing stock structure and boundaries of horse mackerel was initiated by the Northern Pelagic Working Group in collaboration with University College Dublin and Wageningen Marine Research. In 2018, the results of the genetic analysis were published which concluded that the spawners of North Sea and Western horse mackerel can be genetically identified as two distinct stocks. However, at present it is not yet possible to separate the two stocks when they occur in mixed samples. Therefore, a follow-up project has been initiated to carry out a full genome sequencing of horse mackerel which will allow for future analysis of mixed samples. Results are expected in 2020. Furthermore, ICES recommends further analysis on the mixing between the Western stock and the Southern stock in Division 8c: the fishery in the area targets mainly juveniles, would be therefore be very important to understand the impact of this fishery on each of the two stocks.

The UK is due to leave the EU on 31st December 2020, and new UK Fisheries legislation is being developed during 2020. MCS will update ratings with new management information when new legislation comes into force.

In the European Union (EU), EU fishing vessels can fish up to 12 nautical miles of any Member State coast, and closer by agreement. There is overarching fisheries legislation for all Member States, but implementation varies between fisheries, Member States and sea basins.
The EU Common Fisheries Policy (CFP) is the primary overarching policy. Its key environmental objectives are to restore and maintain harvested species at healthy levels (above BMSY), and apply the precautionary and ecosystem-based approaches to fisheries management. To achieve the MSY objective, the MSY exploitation rate is supposed to be achieved by 2020, but this seems unlikely to happen.

The CFP also introduced a Landing Obligation (LO) which bans the discarding at sea of species which are subject to catch limits. Some exemptions apply to species with high post-capture survival, and where avoiding unwanted catches is very difficult. These exemptions are outlined in regional discard plans. Despite quota ‘uplift’ being granted to fleets under the LO, available evidence suggests there has been widespread non-compliance with the policy, and illegal and unreported discarding is likely occurring.
Multi-Annual Plans (MAPs) are a tool for implementing the CFP regionally, with one in place or being developed for each sea basin. They specify fishing mortality targets and ranges for the main targeted species, as well as lower biomass reference points. If populations drop below these points it should trigger a management response. The MAPs also empower Member States to jointly apply measures such as closures, gear or capacity limits, and bycatch limits. There is concern however that the MAPs do not provide adequate safeguards to maintain all stocks at healthy levels.
The EU Technical Measures regulation addresses how, where and when fishing can take place in order to limit unwanted catches and ecosystem impacts. There are common measures that apply to all EU sea basins, and regional measures that vary between sea basins. Measures include Minimum Conservation Reference Sizes (MCRS, previously Minimum Landing Sizes, MLS), gear specifications, mesh sizes, closed areas, and bycatch limits.
The Control Regulation, which is being revised in 2019, addresses application of and compliance with the above, e.g. keeping catches within limits, recording and sharing data, and satellite tracking of vessels over 12 metres (VMS).

Capture Information

Criterion score: 0.25 info

Western horse mackerel is caught by purse seiners in the Norwegian Sea, northern North Sea, the Celtic Seas, Cantabrian Sea, southern English Channel, and Bay of Biscay.

In earlier years most of the Western horse mackerel catches were used for fish meal and oil while in recent years most of the catches have been used for human consumption. The Western horse mackerel fishery is predominantly concentrated in the southern areas, where the Western component mainly occurs at the inner part of the Bay of Biscay and close to Division 9a, where the Southern component is located.

Norway have a directed purse seine fishery for horse mackerel. Germany and the Netherlands have a directed trawl fishery. Spain and Portugal have both directed and mixed trawl and purse seine fisheries. Dutch and German fleets operate mainly west of the Channel, in the Channel area, and in the southern North Sea. Spanish and Portuguese fleets operate mainly in their respective waters. The Irish fleet take Western horse mackerel mainly west of Ireland and Norway in the north-eastern part of the North Sea. Western horse mackerel is caught throughout the year, although, catches vary throughout the year. In 2018, 39.4% of catch was taken by pelagic trawls, and 19.5% by purse seiners, in the directed human consumption fishery. Demersal otter trawls also participated but the trawl fishery is marginal in comparison; 2.7% of total annual catch (2018). Other fishing methods (unspecified and other gears) 38.6%, also contributed to catch, but mainly landed horse mackerel as bycatch in non-directed fisheries.

The pelagic fisheries are deemed to be some of the cleanest fisheries in terms of bycatch, disturbance of the seabed and discarding. Purse seiners are well-targeted with a very low risk of marine mammal bycatch. The pelagic horse mackerel fishery has little to no impact upon the seabed, as there is no contact with the seabed, and therefore no risk to habitats. Purse seines can be associated with bycatch of marine mammals, but there have been no reports of bycatch of Endangered, Threatened or Protected (ETP) species within this fishery, therefore interactions are considered to be low. There have been no reports of bycatch of other non-target species, but where incidental catch does occur, species may include Mediterranean horse mackerel (T. mediterraneus) and blue jack mackerel (T. pictueatus), as they are all found together and are commercially exploited in North East Atlantic waters.

Migrations are closely associated with the slope current, and horse mackerel migrations are known to be modulated by temperature. Continued warming of the slope current is likely to affect the timing and spatial extent of this migration.


Abaunza, P., Gordo, L., Karlou-Riga, C., Murta, A., Eltink, A.T.G.W., Garcıa Santamarıa, M.T., Zimmermann, C., Hammer, C., Lucio, P., Iversen, S.A., Molloy, J. & Gallo, E. (2003). Growth and reproduction of horse mackerel, Trachurus trachurus (carangidae). Reviews in Fish Biology and Fisheries, 13, pp.27–61. Available at [Accessed 10.07.2020]

ICES (2019). Horse mackerel (Trachurus trachurus) in Subarea 8 and divisions 2.a, 4.a, 5.b, 6.a, 7.a–c, and 7.e–k (the Northeast Atlantic). In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, hom.27.2a4a5b6a7a-ce-k8, Available at [Accessed 13.07.2020]

ICES (2019). Working Group on Widely Distributed Stocks (WGWIDE). ICES Scientific Reports. 1:36. 948 pp. Available at [Accessed 09.07.2020]

Luna, S. and Nicolas, B. (2020). Atlantic horse mackerel (Trachurus trachurus). Available at [Accessed 09.07.2020]

MMO (2018). Statutory guidance: Minimum Conservation Reference Size (MCRS) in UK waters. Available at [Accessed 10.07.2020]

Working Group on Widely Distributed Stocks (WGWIDE) (2017). Stock Annex: Horse mackerel (Trachurus trachurus) in Subarea 8 and divisions 2.a, 4.a, 5.b, 6.a, 7.a–c, e–k (the Northeast Atlantic). Available at [Accessed 13.07.2020]