The positions of the hydrographical sections are shown in Figure 1. Figure 5-6 show the distribution of temperature, salinity and oxygen in each section. The surface temperature off Baia dos Tigres, 20-22°C is considerably lower than the surface temperatures found further north. In all areas there is a distinct termocline between about 15 and about 30m depth. Of perhaps even greater significance for the fish distribution is the oxygen content of the different water layers. As can be seen from the figures the oxygen content decreases rapidly through the thermocline to values below 2 and even below 1 ml/l in the southern part. At least the latter figure has been indicated as a lower tolerance level for some fish species. More detailed studies should be made of the possible relationship between oxygen content and fish distribution. For this more observations are needed in between the standard hydrographical sections and a special section was worked off Cabeca da Baleia to the edge of the shelf. From Luanda and northwards two sections show that the 1 ml/l oxycline is situated deeper and off the shelf and should not limit the distribution of the common fishes (Figure 6).
