X-ray images of Baltic herring. Data analysis

Based on the developed methodology for the: (i) optimal method of catching, (ii) transporting and storing fish, (iii) measuring and (iv) analyzing X-rays images, the existing collection of X-ray images of Baltic herring, caught in October 2002 during the Swedish component of the Baltic International Acoustic Survey (BIAS) in the Baltic proper (ICES Subdivisions 25, 27 and 29), has been expanded to include of X-ray images of herring from the Polish coastal zone (ICES Subdivision 26). Newly received X-ray images were used to measure the geometric dimensions of swimbladders. Detailed data on the shapes and geometric sizes of herring bodies and swimbladders for dorsal exposure were obtained for 74 fish individuals. These data were used as the input data in the modelling of the backscattering characteristic of the herring from the Polish coastal zone in order to define the TS(L) relationship, critical to abundance estimation from fisheries acoustic surveys.