A Review on Roughhead Grenadier (Macrourus berglax) Biology and Population Structure on Flemish Cap (NAFO Division 3M) 1991-2004 Based Upon EU Flemish Cap Bottom Survey Data

The European Union has conducted since 1988 an annual bottom trawl survey in Flemish Cap (NAFO Division 3M) in the 200-720 m depth range. The information on roughhead grenadier population structure recorded during the last 14 EU surveys (1991-2004) in Flemish Cap is presented. Depth distribution of captures, length/age distribution of captures, growth rates, sex-ratios, catch curves, and total biomass estimated by the swept area method are presented. Age and length composition of the catches showed clear differences between the two sexes. The importance of males in the capture declines in larger fish, disappearing from the capture in largest length classes. Results show that roughhead grenadier has a prolonged life cycle and multiaged population structure with differences in growth and mortality between males and females