Diet variations of Striped Piggy, Pomadasys stridens (Forsskål, 1775) (Teleostei: Haemulidae) in the northeastern Mediterranean Sea

Abstract

The opening of the Suez Canal started an influx of non-indigenous species into the Mediterranean Sea, yet mechanisms allowing for an introduced species to adapt and thrive are still a topic of debate. Since its recent introduction, the Striped piggy (Pomadasys stridens) has rapidly become one of the most abundant species on the eastern Mediterranean coast. However, no study has investigated feeding biology in its relatively new environment. We predicted the species to have a wide-ranged and flexible diet, contributing to its establishment success. We examined the stomach content of P. stridens in Mersin, Turkey, and assessed external parameters (depth and month) and biological indicators (spawning state and stomach fullness) as factors affecting diet composition. Our findings showed the species to mainly feed on crustaceans (predominantly copepods), followed by annelids (polychaetes and oligochaetes). Sexual maturity affected the diet: once mature, individuals switched from a copepod-based diet to higher trophic level-prey (decapods, peracarid crustaceans, and teleosts). Depth also affected the diet; polychaetes started playing a role in the stomach content below 50 m, whereas copepods were rather prominent for specimens in shallow waters (0–50 m). Stomach fullness, as a factor, showed that poorly fed specimen had a more diverse diet, while well fed specimen mostly preyed on copepods. Our results show P. stridens to have a relatively wide-ranged and adaptive diet which most likely contributes to the establishment of P. stridens in the eastern Mediterranean. Given the lack of fishing pressure and known predators in the region, we recommend close monitoring of the ongoing spread of P. stridens.