Diet composition and variations of Morocco dentex Dentex maroccanus (Sparidae) from Eastern Algeria

Mohdeb R., Derbal F., Kara M.H.

Date de parution: décembre 2017
Volume: 41
Number: 4
Pagination: 317-324
Editeur: Société Française d’Ichtyologie
doi: https://doi.org/10.26028/cybium/2017-414-002
Résumé

Morocco dentex is an important commercial sparid fish on Algerian coasts, where its distribution is irregular. In two sites, Jijel and El Kala areas, located in the northeast of Algeria, 1725 specimens of Dentex maroccanus were caught and examined for diet composition study and trophic level estimation. Their total length (weight) ranged from 10.4 cm (16.05 g) to 26.8 cm (332.47 g). The Relative Importance Index (%IRI) was used to characterize the relative importance of the different food taxa, and their variations in the diet were studied according to season, sex and sexual maturity. Results from both sites were combined for analysis as no difference of vacuity index (VI: χ2 = 0.048, p = 0.82) and diet composition (correlation coefficient of Spearman: rho = 0.82, tobs = 4.61, p < 0.01) was statistically observed between them. The average annual digestive vacuity was 22.85%. It did not vary according to sex and sexual maturity states (χ2(females, males) = 0.04, p = 0.83; χ2(immature, mature) = 0.26, p = 0.6), but differed significantly between seasons. D. maroccanus fed mainly on Pancrustacea (%IRI = 77.26%) and secondarily on Teleostei (%IRI = 21.85%), while Mollusca (%IRI = 0.87%) and Annelida (%IRI = 0.005%) were consumed accidentally. The mean trophic level (TROPH) of D. maroccanus was estimated at 3.91 (SE = 0.67) and varied with season, sex and sexual maturity state. A slightly lower TROPH value was observed in winter compared to the other seasons, while higher TROPH values were recorded in females than in males, and in mature than in immature individuals. According to this study, Morocco dentex is a carnivore with a marked preference for crustaceans and fish.

Mots-clés: Dentex maroccanus - Diet variations - feeding habits - Mediterranean Sea - Sparidae - Trophic level
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