Movements and residence time of spiny lobsters, Palinurus elephas released in a marine protected area: an investigation by ultrasonic telemetry

Abstract

Marine reserves and restocking initiatives are sometimes used as a tool to enhance spiny lobster stocks. In such initiatives it is crucial to follow the movement of lobsters once they are released at sea in restocking experiments.This paper presents the results of the application of an ultrasonic telemetry system to the monitoring of 11 lobsters (90±14 mm mean carapace length) released in the Capo Gallo-Isola delle Femmine Marine Reserve in north-western Sicily, central Mediterranean. The system comprised transmitters glued onto the lobster carapace, and manual as well as automated receivers to locate tagged animals. The data (i.e. number of detected signals) were tested to assess any difference in the diel activity of lobsters. The field study lasted 79 days in total. Lobsters remained in the study area for periods ranging from a few hours to the entire duration of the study. The longest distance travelled by a tagged lobster was 2.2 km. The number of signals varied significantly across the day, with the highest value recorded in the full-light hours (1000–1500), but they were not sufficient to assess clearly the diel activity of the released lobsters.The interpretation of data suggests that: (1) released lobsters preferred a deeper habitat than that of the release site; and (2) the lobsters that reached a rough rocky area with available shelters settled there, while those that did not meet such a habitat soon moved out of hydrophone detecting range.