It is well known that the majority of the species is widely distributed in the Adriatic sea and that some of them migrate over the whole area. For management purposes it is better to consider for all species a unique population over the northern Adriatic sea independently of the "administrative" borders.

The data presented for the three sub-areas can be useful to know the differences in density due to the ecological and fishing effort differences but the situation of the stocks and the general trends can only be estimated over the whole area. For this purpose we have two surveys: 1996 and 1997.

For these two years the most important species is Merluccius merluccius showing a slight decrease from 52.47 kg/km² in 1996 to 48.82 kg/km² in 1997. The other species showing a decrease of the biomass index from 1996 to 1997 are Citharus linguatula (from 2.57 to 1.41 kg/km²), Eledone cirrhosa (from 8.34 to 5.41 kg/km²), Illex coindetii (from 6.09 to 4.33 kg/km²), Lophius budegassa (from 7.92 to 4.91 kg/km²), Micromesistius poutassou (from 14.73 to 5.62 kg/km²), Nephrops norvegicus (from 6.38 to 2.86 kg/km²) and Raja clavata (from 6.29 to 2.49 kg/km².

A small group of species shows an increasing trend in biomass indices. There are Lophius piscatorius (from 0.45 to 0.93 kg/km²), Mullus barbatus (from 14.02 to 21.68 kg/km²), Pagellus erythrinus (from 4.70 to 7.33 kg/km²), Sepia officinalis (from 1.03 to 3.60 kg/km²), Spicara flexuosa (from 3.70 to 6.73 kg/km²), Trachurus mediterraneus (from 1.89 to 4.38 kg/km²) and Trachurus trachurus (from 2.86 to 7.39 kg/km²).

The other species in the list of reference show very small changes between the two years. These trends over the whole area are sometime different from the trends in such or such a sub-area. Furthermore, the period is too short to judge if they are real trends or simply fluctuations