Preliminary acoustic tracking of native and transplanted European lobsters (Homarus gammarus) in an open sea lagoon

Abstract

In a larger release project, European lobsters (Homarus gammarus) under legal size have been captured, checked for magnetic microtags, externally tagged, and released to their home site for population and migration studies. To see if transplanted lobsters behave differently from native lobsters, four acoustically tagged males were released between three stationary hydrophones in an open sea lagoon and tracked continuously for 2–3 weeks. Lobster 1 was from the lagoon, Lobster 2 was transplanted less than 1000 m from its capture location, and Lobsters 3 and 4 were transplanted more than 5000 m. Within a few hours, Lobsters 1 and 2 took up residence in the area of their original home sites. Lobsters 3 and 4 took up residence in the lagoon after extended roaming. Six days after release, Lobsters 1 and 4 engaged in nocturnal activity, Lobster 2 changed locations occasionally without moving long distances, and Lobster 3 did not move. The odd movement patterns in the transplanted lobsters could be caused by their lack of local knowledge. Since rocks caused blocking of the acoustic signals, manual monitoring was needed to confirm the lobster positions. In cryptic animals such as lobsters, a continuous tracking system that can penetrate stones is required.