Habitat-Dependent Variation in the Relative Abundance and Growth of the YOY of Five Species of Mugilids in the South-Western Mediterranean

This work is devoted to the study of the abundance, distribution and growth performance of five Mugilidae species in three types of coastal habitats (coastal sea, estuaries and lagoon) located in a limited geographical area in the south-western Mediterranean (eastern coast of Algeria). The four sites considered (Caroube Beach, Mellah Lagoon, Boukhmira and Mafragh Estuaries) are differentiated by their salinity, which evolves at different intervals. The five species enter the considered paralic environments at very small sizes (2–3 cm TL). Regardless of site, Liza saliens is the most abundant (46.92%), followed by Liza aurata (23.72%), Chelon labrosus (13.96%), Liza ramada (11.80%) and Mugil cephalus (3.50%). Each species has a different occupation profile for each site (date of recruitment, relative abundance and demographic structure). The same is true for daily growth, which is better at Mafragh for L. saliens (0.7 ± 0.13 mm/day), at Boukhmira and Mafragh for L. aurata (0.53 ± 0.08 and 0.48 ± 0.09 mm/day, respectively), at Caroube for L. ramada (0.58 ± 0.12 mm/day) and at Mellah for C. labrosus (0.59 ± 0.14 mm/day) and M. cephalus (0.68 ± 0.17 mm/day). The closeness of the daily growth values for the five species to data obtained by various multi-year ageing methods (scalimetry, otolithometry) shows the validity of using otolith microstructures to determine the age of juvenile 0⁺ Mugilidae. This study shows heterogeneity in the relative abundance, demographic structure and somatic development of the five species considered depending on their habitat and suggests the influence of certain abiotic parameters on some of them. The two most interesting species for aquaculture (Liza ramada and M. cephalus) are relatively the least abundant, but still have interesting potential for freshwater aquaculture, because of their euryhalinity and their interesting maximum length, as well as their relatively fast growth in freshwater. The results of this study are of an applied nature because they contribute to the development of extensive mugilid aquaculture.