Atlantic mackerel

An age-based analytical model (SAM) is used in the assessment, based on catch and tagging data and three survey indices. Partial discarding estimates are included in the assessment but recent discarding is not thought to be significant (ICES 2018).

Some conflicting signals are apparent in the data sources used and some of the time series are still short. Abundance of younger year classes is estimated with some uncertainty but does not have much of an impact on catch advice (ICES 2018).

A benchmark assessment was conducted in 2017 (ICES 2018).

ICES advises that catches in 2019 should not exceed 318,403 metric tons, under an approach aimed at fishing in the long term at maximum sustainable yield (MSY). This represents a significant reduction to 2018's advised 550,948 metric tons, due to both a declining stock and a downwards revision of the previous assessed stock size, along with high current fishing mortality and low recruitment (ICES 2018). 

One of the three spawning components, that in the North Sea is still of a reduced size due to earlier overexploitation, and ICES continues to recommend protection measures including closed areas and seasons and a minimum size (ICES 2018).

Assessment results indicate that the stock has decreased to below its MSY B_trigger point in 2018, for the first time since 2007. Fishing mortality is almost twice F_MSY, and has been above this newly calculated reference point since 1989. In addition, it is currently on an increasing trend, and catches have been increasing since the mid-2000s, and considered to be considerably underreported prior to 2000. Recruitment was strong from the early 2000s but the 2015 and 2016 classes appear to be small, contributing to the reduction in stock size.

However, fishers have reported increases in mackerel numbers in recent years (ICES 2018), a contradiction that has also occurred in past seasons. 

TACs were previously agreed amongst all fishing parties, but since 2008 no agreement has been reached on setting TACs, and quotas have been set unilaterally. In 2014 three of the Coastal States (Norway, the EU and the Faroe Islands) reached an agreement, that was later extended to 2020, including a harvest control rule that uses MSY reference points and linearly reduces the TAC when the stock is below its MSY trigger reference point (Anon 2018). ICES found the strategy to be precautionary in the long term (ICES 2017) but in 2019 the plan was not followed by its signatory countries, who set a TAC constrained by a maximum 20% reduction, even though as the stock is now below its MSY trigger point, the TAC constraint does not apply under the plan. 

Summed quotas set by all fishing parties have continuously exceeded advised catch levels (ICES 2018). 

Total mackerel catches are estimated by ICES and include discards where available, but are considered to be underestimated due to discards, slippage and under-reporting, although discarding and slipping is thought to have decreased (ICES 2018).

With the exception of 1994 and since 2009, total catches have surpassed Set TACs. From 2009, catches have been close to the sum of the quotas set for the entire area, but considerably exceeded ICES’ advice, and have been increasing since 2006. Fishing mortality was also above that foreseen in the management plan, when this was in force. According to ICES, the lack of international agreements on the exploitation of the stock since 2008 is of critical concern, and hinders control of the total exploitation rates.

A wide variety of marine mammals, including several species of whales considered by the IUCN to be endangered, and hooded seals, classified as vulnerable (IUCN, 2009), overlap with mackerel’s distribution in the North-east Atlantic. Limited information is available on bycatch of marine mammals by the fishery but it has been documented in mackerel trawling off southwest Ireland (ICES, 2008c), although, apart from long-finned pilot whale whose status is unknown, it mostly affects non-endangered mammals (IUCN, 2009). Mackerel is an important food source for various marine mammals (ICES, 2008a), but no information could be obtained on the indirect effects of removal of a preferred prey species.

Nesting or overwintering seabirds may also be affected by the fishery on several levels: bycatch of seabirds may occur, though most often documented for longline fishing, and discarding in the fishery can have a considerable impact on the distribution of scavenging seabirds (ICES, 2008c) but no specific information is available on the effects of the mackerel fishery on seabirds in the region.

Many elasmobranchs in the region which also increasingly vulnerable and marine turtles reported towards the south of mackerel’s range (ICES, 2008c) could be at risk of bycatch but no reports are available.

Overall, the bycatch of non-target species in the mackerel fishery is considered minimal (ICES, 2011a). There is some overlap with the Norwegian Spring-Spawning (NSS), in the northern extent of the Atlantic mackerel range, creating some bycatch issues for the vessels targeting mackerel in this area (ICES, 2009b; ICES, 2011b).

The distribution of mackerel spawning areas has changed in recent years and mackerel is being fished in areas where it was not previously found (ICES, 2009b). A westerly shift in the distribution of the mackerel stock is suggested by survey data in 2009 (ICES, 2009b). Consequences of this change can be expected to be substantial and to impact on the future abundance, spawning, growth and recruitment of the stock (ICES, 2008a). High ocean temperatures appear to be influencing mackerel distribution and migration patterns, partly due to high zooplankton concentrations in the western Norwegian Sea (ICES, 2009b). Earlier spawning in the south and earlier migration to northern waters also appear to be a result of the warmer seas and are supported by changes in the timing of the southern fisheries (ICES, 2008a). An increase in the variability of recruitment has also become apparent in recent years (ICES, 2008b).

Most fleets target mackerel with pelagic gear, where direct effects on the ecosystem are not thought to be significant, but demersal trawls are used by Spanish fleets and are known to damage benthic communities besides having a larger rate of discarding (ICES, 2008c).

Last updated on 08 Nov 2012

The south-west mackerel box, an area off the coast of Cornwall in Southern England, was set up in 1981 in order to protect juvenile mackerel in a known nursery area, at a time when fishing effort was particularly high and discarding of small mackerel a major issue. The area was further expanded in 1989 and is closed to mackerel fishing with the exception of handliners. The fishery is also closed in Divisions IIIa and IVb,c on a permanent basis in order to protect the North Sea component and Western juveniles and in Division IVa during the first half of the year (ICES, 2012a).

In addition, in EU waters, the extension to marine areas of the EU Natura 2000 network of special conservation areas, under the Birds Directive 79/409/EEC and the Habitats Directive 92/43/EEC is currently underway and special fishery management measures may be applied.