The ICES has released its advice on horse mackerel stocks for 2021 in the North East Atlantic & Sub Area 8
The ICES has issued advice of fish stock in relation to 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).
ICES advises that when the MSY approach is applied, catches in 2021 should be no more than 81 376 tonnes. This is a 3% decrease on the 2020 recommended quota from the ICES of 83,954 tonnes.
The stock and fisheries are very dependent on the occasional strong year classes. After a long period of low recruitment, the estimates from 2014 have been above average (1983-2018). The spawning stock has been reduced after 2007 and has been close to Blim since 2015. Fish mortality has decreased after 2013, but is still above FMSY.
The stock calculation method was changed after a method revision in 2017 and shows the same trend in stock development as previous stock calculations, but downgrades the spawning stock somewhat and correspondingly the fish mortality is adjusted upwards.
The stock is just above the historically lowest level and this year’s quota council is at a similar level compared to last year. Given that recruitment has recently been above average, the model predicts that the population will increase in 2021.
An audit of the reference points for western horse mackerel was carried out in August 2019 from 911 587 tonnes to 1,168,272 tonnes for MSY Btrigger and from 0.108 to 0.074 for FMSY. The biomass reference points were derived from the lowest biomass estimate (Statistics Norway in 2003) from the stable period where there were no indications of reduced recruitment.
Critical spawning stock level (B glue ): 834 480 tonnes
Precautionary spawning stock level (B pa ):
1,168,272 tonnes Measure limit for maximum long-term yield (MSYB trigger ): 1,168,272 tonnes
Critical fish mortality rate (F glue ): 0.103
Precautionary fish mortality rate (F pa ): 0.074
Fish death rate for maximum long-term yield (F MSY ): 0.074
Agreed fish death rate level in management plan (F MGT ): not defined
Expected fish death rate (F) in 2020: 0.056
Expected spawning stock (SSB) in 2021: 961 512 tonnes
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