Recording long-term heart rate in the Black cod (Paranotothenia angustata) using an electronic datalogger

A unique heart beat datalogging device was either surgically implanted into the peritoneal cavity (internal-fish) or attached by nylon anchor tags to the dorsal fin rays (external-fish) of the black cod Paranotothenia angustata. Both groups had a mean +/- S.E. heart rate of c. 46 beats min(-1) after 24 h, and by 20 days external-fish showed a significant reduction (34 +/- 3 beats min(-1)) whereas internal-fish did not (44 +/- 2 beats min(-1)). In demersal fishes external attachment of an electronic recording device may be preferable to surgical implantation. (c) 2005 The Fisheries Society of the British Isles.