For division 34.1.1, charts of the distribution, length composition, biomass and number of Pagellus acarne P. centrodontus, Dentex polli, D. macrophthalmus and Diplodus vulgaris are given in Figures 12–20 respectively. Two groups of sparids can be distinguished in statistical division 34.3.1 according to the extent of their movements :
Species that undertake rather large geographical migrations that are fished seasonally by several countries. Sparus caeruleostictus, Dentex gibbosus and D. canariensis belong to this category, and have their centres of abundance between 10° and 21°N. In the cold season (February-March), they are mainly distributed between 10 and 16°N and extend over the whole Senegambian shelf. When the water heats up in April-May, a general northward movement takes place, and spawning by these species reaches a maximum between latitudes 19 and 21°N between mid-June and mid-August. Between July and November only juveniles remain south of latitude 21°N, especially in October-November and some of these spawn for the first time. The Kayar Canyon (at approximately 15°N) seems to play an important role in these migrations.
Species that undertake very limited seasonal geographical movements around the centre of their distribution, and which show vertical migrations. Pagellus bellottii and Dentex macrophthalmus belong to this category and appear in the coastal waters in the cold season, where they are caught by beach seines in January-February, at about 50 m depth. During the warm season, the majority of individuals return to deeper waters (30–80 m for P. bellottii and 80–300 m for D. macrophthalmus). Recent observations and calculations of percentages of P. bellottii in relation to depth from Guinea Trawl Survey data have shown that vertical migrations take place seasonally in the areas where there are marked seasonal differences in temperature (i.e. of Mauritania-Senegal, Congo-Angola). By contrast, off Ivory Coast, Ghana and Togo where seasonal temperature variations are much less pronounced, seasonal differences in vertical distribution are also smaller (Figure 21).
Figure 22 shows the distribution of various types between latitudes 21°N and 28°N.
Further details about distribution and migration are given by FAO 1979, Domain 1979, Garcia 1982 and Ba et al., (1986 ).
