Biomass and Length Distribution for Roughead Grenadier, Thorny Skate and White Hake from the Surveys Conducted by Spain in NAFO Divisions 3NO

• Main Authors: González-Troncoso, Diana, González-Costas, Fernando, Paz, Xabier
• Format: Report
• Language: English
• Published: 2006
• Subjects: Pesquerías; Centro Oceanográfico de Vigo; Hake; North Atlantic; Northeast Atlantic
• Online Access: http://hdl.handle.net/10508/604; http://hdl.handle.net/10261/328798

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, form the C/V Playa de Menduíña to the R/V Vizconde de Eza, so, in oder 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 2002-2005 data are original data from R/V Vizconde de Eza. In 2001, there are data from the two vessels for these two species. This year the data were updated, so a new calibration was made. The changes affect the species length distribution. The abundance and biomass were estimated for the period 1997-2005 for roughhead grenadier and thorny skate, and 2001-2005 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 increasing in the last two years, mainly in 2004. Thorny skate indices decreased since 2001 until 2003 and increase in 2004, reaching the second highest value of the series. This year, a slight decreasing occurred, but remained in a high value. For white hake, there were great catches in 2001, and a sharp decreasing since then, broken this year with an increasing in the indices. In 2004, we can see a presence of individuals between 16 and 26 cm