Tracking movements of deep demersal fishes in the Porcupine Seabight, north-east Atlantic Ocean

Miniature acoustic transponders wrapped in bait were deployed on the sea floor in the continental rise and slope regions of the Porcupine Seabight during August 1992. These were ingested by Centroscymnus coelolepis (Chondrichthyes, Selachii) at 1517-1650 m depth, Antimora rostrata (Osteichthyes, Moridae) at 2020-2501 m depth, and Coryphaenoides (Nematonurus) armatus (Osteichthyes, Macrouridae) at 2501-4050 m depth. Fish with baits in their stomachs were tracked using a scanning sonar deployed on the sea floor. All fish had moved out of range of the sonar (500 m) within 3-9 h of the bait reaching the sea floor, indicating no site fidelity. Swimming speed of C. (N.) armatus increased with depth from 0.056 m s-1 at 2500 m to 0.109 m s-1 at 4000 m. This is partially explained by a bigger-deeper trend in fish size.