Age, growth and feeding of anchovy (Engraulis encrasicolus L.) in the Bay of Bénisaf (SW Mediterranean , west Algerian coast)
Age, growth and feeding of anchovy were studied for the first time from samples collected in the Benisaf Bay (west Algerian coast) during summer (spawning period) and autumn (recruitment period) 2007. Age structure and growth parameters were determined by otolith (sagitta) analyses. The von Bertalanffy growth function fitted to age-length data showed that growth was almost achieved during the first year of life. Significant growth difference was recorded between males and females. Growth parameters were for females (L∞=17,46 cm, k=0,31 per year and t0= -3,46 years) and for male (L∞=16,67 cm, k= 0,35 per year and t0= -3,26 years). The parameters of the otoliths (surface, length, weight and width) were significantly correlated with age and fish length (LT) and seem to be a good indicator of somatic growth.
The diet and ontogenetic variations in diet was studied on the same fish used for the study of growth. In all age-class anchovy was strictly zooplanctivorous. Copepods constituted the dominant group (64% O; 81% N), others crustaceans, molluscs larvae and fish larvae are less represented. The main species of Copepods were by order of decrease: C. longimana (89% O; 39% N), O. mediterranea ( 80% O; 8% N) and P. abdominalis (73% O; 6% N). 0-group anchovy fed mainly on small and medium size copepods (80% O; 93% N). Diet of others age groups (1 to 3) was more diversified and large preys were relatively well represented both in occurrence and number: (Copepods: 58% O; 76% N), (Amphipods: 16% O; 8% N) and (Decapods: 15% O; 10% N). The specific richness, the Shannon-Wiener diversity, Pielou index and the food niche width (B) increased from the 0-group to 2-group age and declined in the 3-group age. These results indicated a generalization of the diet in the first age group (0 to 2 years), and a relative specialization in the third age group.
Bacha Mahmoud, Amara Rachid, Benmansour n, Brylinski Jean-Michel, Moali a, Mahe Kelig (2009). Age, growth and feeding of anchovy (Engraulis encrasicolus L.) in the Bay of Bénisaf (SW Mediterranean , west Algerian coast). 4e Rencontres de l’Ichtyologie en France, 2009, Paris. https://archimer.ifremer.fr/doc/00012/12277/