Horse mackerel

The stock is in a very healthy state and fishing pressure is well within sustainable limits.The spawning stock biomass (SSB) has been above MSY Btrigger (181,000 tonnes) over the whole time-series, with an overall steep increase in the last few years. SSB is currently at its highest level (1,155,488 tonnes in 2022). In 2022, the ratio of B:BMSY was 6.4. Fishing mortality (F) (0.022 in 2021) has been below the maximum sustainable yield (FMSY) (0.15) over the whole time-series, and has remained relatively stable over the entire time-series. In 2021, the ratio of F:FMSY was 0.15. Recruitment (R) appears to have declined to 5 billion in 2021 and 2022 down from the average of 2012-2021 of 11 billion due to the different range of years used for the geometric mean recruitment assumptions.ICES advises that when the MSY approach is applied, catches in 2023 should be no more than 165 173 tonnes. The advice for 2023 has increased compared to the advice provided for 2022 owing to the increasing biomass estimate.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.

There are management measures in place, which are partly effective in managing the stock.A management plan (MP) was proposed for this stock and has been evaluated as precautionary by ICES. The MP was modified in 2021 by setting the Ftarget (fishing target) to be achieved by 2022 and is considered precautionary. ICES was requested by the EU to base its advice for 2023 on ICES MSY approach and include the MP as a catch scenario so the management plan has not been fully adopted.Management of Southern horse mackerel, blue jack mackerel, and Mediterranean horse mackerel is under a combined Total Allowable Catch (TAC), which prevents the effective control of the single-species exploitation rates, and could lead to overexploitation of any of the mentioned species. ICES advice pertains to horse mackerel, while the total allowable catch (TAC) is set for several Trachurus species, including blue jack mackerel and Mediterranean horse mackerel. Part of the catches consist of other Trachurus species, and the percentage composition can vary from year to year. Estimates indicate that in 2021, 23% of the catch consisted of Trachurus spp. other than horse mackerel (6712 tonnes). ICES considers that management of several species under a combined TAC prevents effective control of the single-species exploitation rates and could lead to overexploitation of any of these species.The catch advice has been steadily increasing from 73,349 tonnes in 2017 to 165,173 in 2023, using the MSY approach. Part of the catches consist of other Trachurus spp. than T. trachurus, and this percentage can vary from year to year. Estimates indicate that in 2019, less than 10% of the catch consisted of Trachurus spp. other than T. trachurus (2,377 tonnes). Since 2014, TACs have been set in line with advice. Compliance to the TAC is high. Observed catches have always been below the advised TAC in the available time-series. TAC for this species has not been limiting, in recent years this has been due to low market value and opportunities (landings on average 38% of the TAC; 2017-2021).Information on current discarding indicates it is negligible.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.Both the EU and UK have fishery management measures in place, which can include catch limits, targets for population sizes and fishing mortality, and controls on what fishing gear can be used and where. In the EU, compliance with regulations has been variable, and there are ongoing challenges with implementing some of them. There was a target for fishing to be at Maximum Sustainable Yield by 2020, but this was not achieved. The Landing Obligation (LO), an EU law that the UK has kept after Brexit, requires all quota fish to be landed, even if they are unwanted (over-quota or below minimum size). It aims to promote more selective fishing methods, reduce bycatch, and improve recording of everything that is caught, not just what is wanted. Compliance with the LO is generally poor and actual levels of discards are difficult to quantify using the current fisheries observer programme. UK administrations are in the process of replacing the landing obligation with country-specific Catching Policies.In the UK, it is too early to tell how effective management is, as the Fisheries Act only came into force in January 2021. The Act requires the development of Fisheries Management Plans (FMPs) (replacing EU Multi-Annual Plans). FMPs are currently in development, but the scope of them remains unclear. They have the potential to be very important tools for managing UK fisheries, although data limitations may delay them for some stocks. MCS is keen to see publicly available FMPs for all commercially exploited stocks, especially where stocks are depleted, that include:Targets for fishing pressure and biomass, and additional management when those targets are not being met, based on the best available scientific evidenceTimeframes for stock recoveryImproved data collection, transparency and accountability, supported by technologies such as Remote Electronic Monitoring (REM)Consideration of wider environmental impacts of the fishery

Most southern horse mackerel is caught by purse seiners. 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 is deemed to be low.Southern horse mackerel is caught by purse seiners (64% in 2021), in the Iberian coast from the Strait of Gibraltar to Cape Finisterre in Galician waters (of the Spanish and Portuguese coast). Southern horse mackerel is caught throughout the year and taken by directed fisheries, all catches are used for human consumption.Southern horse mackerel are targeted by a small number of fleets, which are defined by the gear type (bottom trawl, purse-seine and artisanal) and country (Portugal and Spain). Until 2011 the highest contribution to the total catches was, in general, from the trawl fleets. Since 2012, there has been a significant increase in the catches from the purse-seine. The contribution of the artisanal fleet from both Portugal and Spain is very small, respectively representing 4% and 1% of the total catches in 2019. The Portuguese artisanal fleet is mainly composed by small size vessels licensed to operate with several gears (gillnets, trammel nets, and lines).In 2021, 64% of catch was taken by purse seiners, 31% by demersal otter trawls, and 5% by the artisanal fisheries using other fishing gears.The pelagic fisheries are deemed to be some of the cleanest fisheries in terms of bycatch, disturbance of the seabed and discarding. Purse seiner fisheries are well targeted, and have low risk of marine mammal bycatch. 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, although, incidental catch may sometimes occur. 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. Moreover, horse mackerel is a schooling species and often close to the sea floor, sharing the same habitat with other fish and invertebrate species. These species are mainly: snipefish, boarfish, blue whiting, European hake, sardine, blue jack mackerel, squid and pelagic crabs. These species are found together in the stock area and most of them are commercially exploited, hence fishing mortality for horse mackerel could affect the yield of all other species and vice versa.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.Young horse mackerel are a feeding resource consumed by several demersal, benthic and pelagic predators present in the distribution area like hake, monkfish, rays and dolphins, but does not seem to be the favoured prey among the area predators. Some recent unpublished work suggests an increase in the predation pressure from hake on small to medium-size horse mackerel is probably reflective of the recovery of the hake stock coupled with the high abundance levels of horse mackerel. Horse mackerel is mainly a zooplanktivorous species and become ichthyophagic when they reach large sizes, also being less targeted by predators. Even though horse mackerel prey on fish as they grow, they show a comparatively lower consumption of fish, being euphausids (Meganyctiphanes norvegica and Nyctiphanes couchi) and decapods (Pasiphaea sivado) as the most important preys.Horse mackerel in this area are vulnerable to the effects of changing climatic conditions, which will most likely affect the abundance, distribution and composition of fisheries catches.To improve monitoring and reporting of fishing activity, MCS would like to see remote electronic monitoring (REM) with cameras implemented, used and enforced. To reduce the impacts of fishing on the marine environment we would like to see a just transition to the complete removal of bottom towed gear from offshore Marine Protected Areas designated to protect the seabed. We also want to see reduction and mitigation of environmental impacts including emissions and blue carbon habitat damage.

Abaunza, P., Gordo, L., Karlou-Riga, C. et al. (2003). Growth and reproduction of horse mackerel, Trachurus trachurus (carangidae). Reviews in Fish Biology and Fisheries 13, 27–61, https://doi.org/10.1023/A:1026334532390ICES (2019). Bay of Biscay and the Iberian Coast ecoregion - “ Ecosystem overview. In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, Section 6.1, https://doi.org/10.17895/ices.advice.5751. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/EcosystemOverview_BayofBiscayandIberianWaters_2019.pdf [Accessed 14.07.2020]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]ICES (2020). Horse mackerel (Trachurus trachurus) in Division 9.a (Atlantic Iberian waters). In Report of the ICES Advisory Committee, 2020. ICES Advice 2020, hom.27.9a. https://doi.org/10.17895/ices.advice.5904. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2020/2020/hom.27.9a.pdf [Accessed 14.07.2020]ICES (2020). Working Group on Southern Horse Mackerel, Anchovy and Sardine (WGHANSA). Draft report. ICES Scientific Reports. 2:41. 513 pp. http://doi.org/10.17895/ices.pub.5977. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/Fisheries%20Resources%20Steering%20Group/2020/WGHANSA/01%20WGHANSA%20-%20Report%20of%20the%20Working%20Group%20on%20Southern%20Horse%20Mackerel,%20Anchovy%20and%20Sardine.pdf [Accessed 14.07.2020]ICES, 2021. (Azevedo, M. Costas, G. and Mendes, H.). Stock Annex: Southern Horse Mackerel (hom 27.9.a). Available at https://figshare.com/articles/report/Stock_Annex_Southern_Horse_Mackerel_hom_27_9_a_/18623330 [Accessed 20.07.2022]ICES. 2022. Horse mackerel (Trachurus trachurus) in Division 9.a (Atlantic Iberian waters). In Report of the ICES Advisory Committee, 2022. ICES Advice 2022, hom.27.9a, https://doi.org/10.17895/ices.advice.19448030Luna, 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]Seafish, 2022. PS - Purse Seine. Available at: https://www.seafish.org/responsible-sourcing/fishing-gear-database/gear/ps-purse-seine/ [Accessed on 11.8.22]