Horse Mackerel, Scad

Trachurus trachurus

Method of production — Caught at sea
Capture method — Pelagic trawl
Capture area — North East Atlantic (FAO 27)
Stock area — Skagerrak and Kattegat, North Sea (Central and South), English Channel (East). North Sea stock.
Stock detail — 3a, 4b, 4c, 7d
Picture of Horse Mackerel, Scad

Sustainability rating four info

Sustainability overview

Updated: July 2020.

This is a data limited stock, and trends are used to indicate its state. Trends suggest that there is concern for the biomass and fishing mortality. The North Sea 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 has not been reported within this fishery. Habitat impacts from pelagic trawling is deemed to be very low.

Biology

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: 1 info

This is a data limited stock, and trends are used to indicate its state. There is concern for the biomass and for fishing pressure. Horse mackerel has a medium resilience to fishing pressure.

Reference points for biomass (B) are not defined, so trends in abundance index (fish >20 cm length in the stock) are used instead. A proxy for FMSY (the maximum rate of fishing mortality, i.e. the proportion of a fish stock caught and removed by fishing, that can sustain a healthy stock level), is provided within the assessment. Since 1992, the abundance of horse mackerel has shown a mostly continuous decline and surveys carried out in 2019 indicate that the stock remains at a low level. The average abundance value for the 2017–2018 period was estimated to have declined >20%, compared to the 2014–2016 period. In 2018, the abundance of fish increased marginally from the previous year, 0.145 to 0.172 (2017-2018), yet, it was at one of the lowest points in the time series (1992-2018). The harvest-rate index displays catches in 2009 to be at one of the highest levels within the time-series, coinciding with a significant decline in abundance, thereafter, decreasing 68% from 44,847 tonnes (2009) to 14,508 tonnes (2018). In 2019, ICES assesses that fishing pressure on the stock is above the FMSY proxy (fishing at the maximum sustainable yield).

ICES advises that when the precautionary approach is applied, catches should be no more than 14,014 tonnes in each of the years 2020 and 2021. The advice has decreased 20% from last year (17,517 tonnes), following the decline in the abundance index (>20%).

Horse mackerel in the north east 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.

Management

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, and there is no management plan for horse mackerel in this area. ICES evaluated a proposed harvest control rule for a multi-annual plan for horse mackerel in the North Sea in 2014, however, none of the options were considered as being in accordance with the precautionary approach.

This fishery is currently managed by an annual Total Allowable Catch (TAC), which has been in place (Divisions 3a, 4c-d, 7d) since 2010. The TAC is set by EU therefore only apply to EU waters and the EU fleet in international waters. Considering the majority of catches are taken in Division 7d in the eastern English Channel, the total of North Sea horse mackerel catch is effectively constrained by the TAC, since a realignment of the management areas in 2010. TACs have been set in line with scientific advice since 2015, however, there is uncertainty in the assessment as further work is necessary to develop an index of stock biomass. In 2017 and 2018 the TAC was set 13% lower than advice. Compliance to the TAC is high, with total annual catches on average 89% of the TAC; 2015-2018. Historically, TACs have not limited catches and even with significant reduction in TAC and advice in recent years, it has not been low enough to limit catches; 2017 and 2018.

Discarding in the targeted pelagic horse mackerel fishery is considered to be negligible. Information from national data submitters suggest that discard rates for the directed fishery are low with the majority of discards from non–directed demersal fisheries. Reported discards have decreased from 14% in 2015 to 2% in 2018.

Beyond TACs the fishery is managed by a minimum landing size of 15 cm for horse mackerel (10% undersized allowed in the catches), 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.

There is some overlap of the North Sea horse mackerel fishery and the Western stock. Catches in the Western Skagerrak (Division 3a) are variable, with catch in the last half of the year considered to be from the Western horse mackerel stock, while catches in the first half of the year are considered to be from the North Sea horse mackerel stock. There is also potential of mixing between both stocks 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.


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

North Sea horse mackerel is caught by pelagic trawling in the Skagerrak and Kattegat, southern and central North Sea, and eastern English Channel.

In earlier years most of the North Sea 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 North Sea horse mackerel fishery occurs predominantly in the eastern English Channel, with the highest catches taken by the Netherlands, followed by the UK, Germany, France and Norway; 2018. The majority of horse mackerel is caught in the last quarter of the year, although fishing occurs throughout the year. In 2018, 60.2% of horse mackerel was taken by pelagic trawls, in the directed human consumption fishery. Other fishing methods: (unspecified) 34.1%; seine 3.3%; demersal Otter Trawl 2.4%, also contributed to catch, but were marginal in comparison and most of which 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. Pelagic trawling is a well-targeted method 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. Pelagic trawls 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 may 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.

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.

Anchovy, anchovies
Arctic char
Herring or sild
Horse Mackerel, Scad
Kingfish, yellowtail
Mackerel
Salmon, Atlantic (Farmed)
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Swordfish
Trout, Rainbow
Tuna, albacore
Tuna, skipjack
Tuna, yellowfin

References

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 https://core.ac.uk/download/pdf/34725233.pdf [Accessed 10.07.2020]

ICES (2019). Horse mackerel (Trachurus trachurus) in divisions 3.a, 4.b–c, and 7.d (Skagerrak and Kattegat, southern and central North Sea, eastern English Channel). In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, hom.27.3a4bc7d, https://doi.org/10.17895/ices.advice.4884. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/hom.27.3a4bc7d.pdf [Accessed 09.07.2020]

ICES (2019). Working Group on Widely Distributed Stocks (WGWIDE). ICES Scientific Reports. 1:36. 948 pp. http://doi.org/10.17895/ices.pub.5574. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/Fisheries%20Resources%20Steering%20Group/2019/WGWIDE/01%20WGWIDE%20Report%202019.pdf [Accessed 09.07.2020]

Luna, S. and Nicolas, B. (2020). Atlantic horse mackerel (Trachurus trachurus). Available at https://www.fishbase.de/Summary/SpeciesSummary.php?ID=1365&AT=horse+mackerel [Accessed 09.07.2020]

MMO (2018). Statutory guidance: Minimum Conservation Reference Size (MCRS) in UK waters. Available at https://www.gov.uk/government/publications/minimum-conservation-reference-sizes-mcrs/minimum-conservation-reference-sizes-mcrs-in-uk-waters [Accessed 10.07.2020]

Working Group on Widely Distributed Stocks (WGWIDE) (2017). Stock Annex: Horse mackerel (Trachurus trachurus) in divisions 3.a, 4.b-c and 7.d (Skagerrak and Kattegat, southern and central North Sea, eastern English Channel). Available at http://www.ices.dk/sites/pub/Publication%20Reports/Stock%20Annexes/2017/hom-nsea_SA.pdf [Accessed 09.07.2020]