Acoustic survey of deep-water fish of the Skagerrak

Introduction: Two fish species, the greater silver smelt Argentina silus and the roundnose grenadier Coryphaenoides rupestris, are highly abundant in the deep-water areas of the Skagerrak. Since the 1970s, a small aimed trawl fishery for the smelt has developed and now also some grenadier is landed. The biology and general distribution of both species have been described from the Skagerrak and elsewhere. Due to their benthopelagic distribution at depths from 200 to 700 m, previous attempts at estimating abundance and biomass of the Skagerrak concentrations yielded unsatisfactory results. In April 1992, during what appears as a major spawning season of the greater silver smelt, abundance estimation by the SIMRAD EK500 echo sounder and integrator was attempted. Comparisons were made between observations made by the hull-mounted transducer and a transducer mounted in a newly developed towed body