Insights into the distribution and ingestion of prey-like plastic fishing lures in Mediterranean rough-toothed dolphins

Rough-toothed dolphins (Steno bredanensis) form an isolated subpopulation in the Mediterranean Sea that resides only in the eastern basin. Due to the paucity of records, the conservation threats these dolphins face and their ecology and distribution are poorly understood. While most observations indicate that individuals are found in two isolated clusters in the eastern basin, we hereby present five observations-three visual, one acoustic and one stranding-that possibly extend the range of this subpopulation to the entire offshore waters of the eastern basin. The stomach content remains of the stranded individual revealed a diet based on epipelagic squids and octopods. The stranded dolphin had also consumed seven plastic bags and nine squid-like plastic fishing lures, which had caused a complete gastric blockage and probably led to the stranding. High pollution loads from macroplastics in the Mediterranean Sea may evolve into a new potential threat for this subpopulation.

Automated summary

Rough-toothed dolphins, an isolated subpopulation in the Mediterranean Sea, may have a wider distribution in the offshore waters of the eastern basin than previously thought. Their diet consists of epipelagic squids and octopods, but they are also at risk from consuming plastic pollution, as evidenced by a stranded dolphin with a complete blockage caused by plastic bags and fishing lures. The high pollution loads of macroplastics in the Mediterranean Sea may pose a new potential threat to this subpopulation.