SEASONALITY OF PALEOLITHIC FISHERIES IN UPPER EGYPT REVEALED BY HIGH-RESOLUTION ISOTOPIC ANALYSIS OF OTOLITHS

Reconstructing the resource scheduling is one of the main concerns in archeology because it allows for interpretation of subsistence strategies and for discrimination between sedentary and nomadic settlements. Hundreds of tilapia (Oreochromis niloticus) otoliths found in the late Paleolithic site of Makhadma in Upper Egypt dated 12,500 years BP demonstrate that this species was intensively exploited. However, temporal conditions of this exploitation need to be better documented. Fish could have been captured 1) from the Nile, 2) at the beginning of annual floods in shallow marginal waters, 3) in residual pools formed as the water-level on the floodplain falls. High-resolution isotopic analyses of otoliths have been used to determine the season of death and thus the moment of capture. The isotopic composition of otolith aragonite is linked to physical parameters of the environmental water. The sequential sampling along the ontogenetic growth axis yields cyclic patterns related to seasonal environmental changes. The very high oxygen isotopic values indicate the dominant influence of evaporation and aridity on the isotopic signal of water. The pattern of isotopic profiles indicates that capture occurred after the period of highest humidity and therefore after the maximal floods in residual pool at one time of the year. Paleoclimatic implications and limitations due to possible diagenetic alteration will also be discussed.