Report of the Study Group on Fish and Fisheries Issues in the BSRP (SGBFFI)

The hydrocoustic survey database on herring growth is completed with inclusion of Russian data. This database comprises all herring individual data from 1986 to 2003 sampled in ICES SD 25–29. The successive step will be to recalculate the growth and condition indices, as weight at age and weight at length, after the inclusion of the Russian data and to test of the effect of both biotic and abiotic variables on growth of herring for the different areas of the Baltic Sea. For this purposes, estimate of abundance from MSVPA could be used as an index of density dependence while time series of zooplankton data available from different sources might constitute an index of food abundance in the sea. Also, abiotic factors as temperature and salinity should be included into the analysis. Finally, a modified von Bertalanffy growth curve or a power curve (Miller et al., 1999) where weight at age is dependent to both biotic and abitioic factors could be suitable candidate for including growth in stock short term forecast