Biomass and length distribution for Roughhead grenadier, Thorny skate and White hake from the surveys conducted by Spain in NAFO 3NO

Data for Roughhead grenadier (Macrourus berglax), Thorny skate (Amblyraja radiata) and White hake (Urophycis tenuis) from Spanish Spring survey are presented. The survey vessel changed in 2001, from the C/V Playa de Menduíña to the R/V Vizconde de Eza, so, in order to maintain the historical series, we transformed the data for Roughhead grenadier and Thorny skate until that year. 1997-2000 data are transformed data from the C/V Playa de Menduíña and 2002-2007 data are original data from R/V Vizconde de Eza. In 2001, there are data from the two vessels for these two species. The abundance and biomass were estimated for the period 1997-2007 for Roughhead grenadier and Thorny skate, and 2001-2007 for White hake. The length distribution was obtained and presented in numbers per haul stratified mean catches. The indices of Roughhead grenadier present no trend along the years until 2003, with an increase in the years 2003-2006, mainly in 2004. This year the biomass decreased under the level of the year 2003. Thorny skate indices decreased since 2001 until 2003, increased for 2004-2006 and decreased again in 2007. For White hake, there were great catches in 2001, and a sharp decrease since then, broken in 2005 for an increase in the indices, but a new decrease in 2006 and 2007. 2007 biomass is the lowest value if the series. In 2004 we can see a good presence of individuals between 16 and 26 cm