Trophic niches of two predator fish cohabiting in the Algerian coastal ecosystem: Scorpaena porcus (Linnaeus, 1758) and Scorpaena notata (Rafinesque, 1810)

The diet of adult specimens of black scorpionfish Scorpaena porcus (Linnaeus, 1758) and small red scorpionfish Scorpaena notata (Rafinesque, 1810), collected from the Algerian coast was studied using different coefficients and trophic indexes. The inventory of ingested prey indicates that the focal species have a diverse diet that covers different zoological groups. Their feeding spectrum is mainly composed of brachyuran crabs and other crustaceans such as isopods and shrimp. Fish and molluscs are only occasionally ingested. The vacuity coefficient average exceeded the estimated rate of 40%. The observed monthly fluctuations revealed a seasonal alimentary rhythm. The foraging activity of the two scorpionfish decreases in summer, during gonad maturation. This decrease is highlighted by the increase in the vacuity coefficient and the decrease in the repletion index. Despite a similarity in the food bolus, the two co-occurring fish exhibit a specialized diet. This was observed especially in mature individuals. In conclusion, our results demonstrated a very strong overlap of niches between two scorpionfish species.