The ICES has released its advice on mackerel stocks for 2021 in the North East Atlantic
The ICES has released it’s advice for fish stocks in the North East Atlantic and adjacent waters for 2021.
On Mackerel the ICES advises that when the MSY approach is applied, catches in 2021 should be no more than 852, 284 tonnes, a decrease of 8% on last year.
The spawning-stock biomass (SSB) is estimated to have increased since 2007, reaching a maximum in 2014, and has been declining since then. It has, however, remained above MSY Btrigger since 2008. The fishing mortality (F) has declined since 2003, and is estimated to have been below FMSY since 2016. There has been a succession of large year classes since 2001, with year classes since 2011 estimated to be above average.
The mackerel stock is still in good condition and has consistently good recruitment, but the stock level has been slightly downgraded from last year. The spawning stock is estimated to be 3.6 million tonnes in 2021.
As in previous years, the assessment indicates conflicting signals between some of the data sources. The International Ecosystem Summer Survey in the Nordic Seas (IESSNS) index has remained at high levels since 2013, while the triennial egg survey index has been at low levels since 2016. This contradictory information led to a decrease in the influence of those data sources in the assessment. The tagging data series is still short with only six years of recapture. In addition, the egg survey provides an SSB estimate every three years, with the most recent estimate in 2019. The inclusion of any additional year of data for these time series may modify the relative weight of the different data sources in the assessment, causing a revision in the level of the SSB and mean F. The retrospective pattern was less evident this year compared to last year.
ICES evaluated management strategies for mackerel in 2020 on the request of the EU, Norway, and Faroe Islands (ICES, 2020a). During this evaluation, the reference points were also revised. The new FMSY on which the current advice is based (0.26) is higher than the previous value (0.23). ICES currently considers the NEA mackerel stock to consist of three spawning components: western, southern, and North Sea (ICES, 2016), although the stock structure and spawning behaviour is likely to be more dynamic (Jansen and Gislason, 2013). The existing management measures to ensure the protection of the North Sea component (i.e. no mackerel fishing in divisions 3.a and 4.b–c, except for Norway, where a limited amount of the TAC can be fished in Division 3.a; no mackerel fishing in Division 4.a during the period 15 February–31 July; and a 30 cm minimum conservation reference size) should remain in place for precautionary reasons. However, given the new knowledge on stock structure of mackerel that is currently becoming available, a review of the appropriateness of the use of stock components and the associated protection measures should be carried out.
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