Roughhead grenadier (Macrourus berglax) on the shelf edge of the northeastern Norwegian Sea, 1997–2020: Distribution, abundance, size and age structure, growth

Abstract

Records of roughhead grenadier (Macrourus berglax) in a time series of bottom trawl surveys along the Norwegian Sea shelf edge off Norway and Spitsbergen (between 68 and 80 °N in ICES subareas 1 and 2) confirmed that the species is widely distributed in the depth range 500−800 m. Abundance consistently declined to low levels towards northern areas along the Spitsbergen shelf. A corresponding decline was not observed towards the south, reflecting that the distribution area extends southwards beyond the sampling area. Throughout the bottom trawl survey time series 1997–2020, abundance and biomass varied without any apparent temporal trend. Size distributions comprised the entire size range and were usually bimodal. The mode of small fish varied and was comparatively high in some years (e.g. 2009 and 2015), suggesting some temporal variation in recruitment. Age distributions and growth data are presented based on data collected in the period 2009−2017.