Biological and hematological studies on marine coastal fishes, Family Gobiidae, in Alexandria-Egypt

Abstract

The present study aims to give some information on the temporal and spatial distribution of coastal fish populations in Alexandria waters to evaluate the effect of environmental conditions on these populations. It was found necessary to choose one species, as representative of coastal •fishes. The black gobies, Gobius niger, due to their becoming of commercial interest, beside the fact that they are available the whole year round, were chosen for the present study. A description of the growth, feeding habits, reproduction and hematology of this species is given.

The diving census technique used in the present study gave an estimate of 49 fish species in the study area. The total number of species observed during the whole year was highest at Kayet Bey station, while it was lowest at Stanley station. The number of species observed in the four stations under study showed an increase in spring and summer more than in autumn and winter- Family Sparidae was the most abundant in respect of number of species, 12 species, followed by family Lab idae, 5 species and families Gobiidae and Serranidae, 4 species for each. These four families included 51% of the total number of species recorded during the present study. Families Siganidae, Carangidae, Mugilidae and Scorpaenidae ere represented by 2 species, while the rest of the families observed at the study areas were represented by only one species for each. In addition, the largest number of species of family Sparidae was found at Montaza and Kayet Bey, 9 for each, followed by Miami, 8 species. The number of species that were recorded as rare during the present study exceeded that of abundant and common species, respectively, at all stations throughout the year. Kayet Bey, Miami and Montaza contained the largest number of rare species, while Stanley had the lowest. The number of common species was similar at all stations, while the abundant species were present mostly at Kayet Bey. Despite differences in fish assemblage structure between stations some fish species were abundant in all stations, with some seasonal variations: Oblada me/anura, Diplodus annularis, Diplodus sargus (Sparidae), followed by Siganus luridus and Siganus rivulatus (Siganidae).