Influence of environmental variability on anchovy early life stages (Engraulis encrasicolus) in two different areas of the Central Mediterranean Sea

Abstract

The survival of early stages of small pelagic fish species (e.g. Engraulis encrasicolus) is highly dependent on environmental conditions in both spawning and nursery areas. Knowing the relationship between the mortality rates of the early stages and the environment may help to study and model recruitment fluctuations. During the summer of 2006, two consecutive oceanographic cruises were carried out in the Central Mediterranean sea (CMED) in two different areas: the western Libyan waters and the Sicilian–Maltese waters. For the first time a nearly synoptic comparison between the two border areas of the CMED is performed. In spite of a higher overall egg density in the Sicilian–Maltese waters, there was a higher density of anchovy larvae in Libyan waters. The comparison between the oceanographic datasets singled out different circulation patterns and different characteristics of water masses, which helped to explain the differences in density of the spawning products in the two areas. A Lagrangian transport model was used to evaluate the effects of major oceanographic features on offshore egg and larval transport. The results of the model simulations and the nutritional conditions, as indicated by lipid, carbohydrate and protein contents, support the hypothesis that the western Libyan waters may represent a more favourable nursery ground compared to the Sicilian–Maltese waters in terms of environmental conditions and food availability.