Biomass and length distribution for roughhead grenadier, thorny skate and white hake from the surveys conducted by Spain in NAFO 3NO

Abstract

Data for roughhead grenadier (Macrourus berglax), thorny skate (Amblyraja radiata) and white hake (Urophycis tenuis) from the Spanish Spring survey are presented. Abundance and biomass were estimated for roughhead grenadier and thorny skate for the period 1997-2015 and for white hake for the period 2001-2015. The length distribution is presented as numbers per haul stratified mean catches for the last five years (2011-2015). The roughhead grenadier indices showed no discernible trend until 2012, reaching a maximum in 2004 - 2006 and afterwards stabilised at levels slightly higher than in the early years. In the last two years a decline was appreciated in the indices, reaching in 2014 one of the lowest values of the entire time-series, increasing again in 2015. Thorny skate indices follow a large oscillating trend, dropping in 2007 and being since then more or less stables at a low level, reaching the minimum of the series in 2014. White hake indices were highest in 2001 and then showed an overall decreasing trend until 2008 with low values. Indices increased since then until 2013 but declined again in 2014, increasing sligthly in 2015. A small recruitment event was detected in 2005 and in 2013, with individuals between 16 - 26 cm.