Quantifying changes in abundance, biomass and spatial distribution of Northeast Atlantic (NEA) mackerel (Scomber scombrus) in the Nordic Seas from 2007 to 2014

Leif Nøttestad, Kjell Rong Utne, Gudmundur .J. Óskarsson, Sigurdur Jonsson, Jan Arge Jacobsen, Øyvind Tangen, Valantina Anthonypillai, Sondre Aanes, Jon Helge Vølstad, Matteo Bernasconi, Høgni Debes, Leon Smith, Sveinn Sveinbjörnsson, Jens C. Holst, Teunis Jansen, Aril Slotte

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The Northeast Atlantic (NEA) mackerel (Scomber scombrus) is a widely distributed pelagic fish species that plays a key role in the marine ecosystem.
In recent years, there has been a large fishery targeting mackerel in the NEA. At the same time as the geographic range of the mackerel fishery has
expanded and the spatial distribution of the stock been defectively determined, the stock assessment has been considered to be highly uncertain by
ICES. Limited tuning data, with only a triennial egg survey, have created challenges for the assessment and management of NEA mackerel, and ICES
has repeatedly stated the need for an annual age-disaggregated abundance index of this stock. These were the motivations for establishment of an
international pelagic trawl survey in 2007, the International Ecosystem Summer Surveys in the Nordic Seas (IESSNS). The estimated total biomass
indices for NEA mackerel based on coordinated and standardized swept-area surface trawling in July–August from IESSNS increased from 1.96
million t [relative standard error (RSE) ¼ 30.35%] in 2007 to 8.77 million t (RSE ¼ 7.95%) in 2014. Simultaneously, the mackerel stock expanded
its geographic range during the feeding season from 1.3 million km2 in 2007 to at least 2.9 million km2 in 2014, mainly towards western and northern
regions of the Nordic seas. Estimates of abundance indices by age group were fairly precise (RSE 20%) for ages 3–12, while the precisionwas
poorer for ages 1 and 2 and for age groups 13 and older (RSE . 50%). Furthermore, evaluation of the performance of the estimated abundance
indices by age for this time-series, based on internal consistency and catch curves, suggest that the abundance indices of ages 3–12 track the temporal
variation in abundance reasonably, and thus is applicable for stock assessments
Original languageEnglish
JournalICES Journal of Marine Science
Volume73
Issue number2
Pages (from-to)359-373
ISSN1054-3139
DOIs
Publication statusPublished - 2016

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