Movements and behaviour of European common cuttlefish Sepia officinalis in English Channel inshore waters : first results from acoustic telemetry

The increasing importance of the European common cuttlefish Sepia officinalis as a commercial fishery resource raises concerns that our limited understanding of its behaviour and movements in natural habitats may impede future management for this species. Whilst information regarding the fine-scale movements and behaviour of small marine species such as cuttlefish can be difficult to obtain, the increasing miniaturisation of electronic tags, combined with novel attachment techniques, has now enabled tracking of this cephalopod. In this study we describe the first use of electronic tags attached to adult and sub-adult S. officinalis to monitor their movements and behaviour within natural environments. Eight adults (170–205 mm dorsal mantle length [DML]) were fitted with continuous acoustic transmitters and ten sub-adults (132–180 mm DML) were fitted with coded acoustic transmitters. All transmitters were attached to the internal cuttlebone of the living animal. Tagged animals recovered rapidly from anaesthesia and surgical procedures and were found to retain tags for periods of up to 11 weeks in this short-term study. Six of the eight adult cuttlefish released into a radio–acoustic positioning (VRAP) array left the area rapidly (≤ 45 min) whilst two remained for multiple days (≤ 9 days). Short-term site fidelity at a local level was observed in only two adults, whilst larger scale movements along the coastline (≤ 35 km) occurred in three adults, indicating that a complex range of spatial behaviour patterns could occur among spawning adults. Similar patterns were observed in the space use of sub-adults monitored using a passive acoustic-receiver array on the seabed. Three sub-adults were detected within the study area over an extended period of time (≥ 73 days), whilst the remaining sub-adults left the study area rapidly and without return. The capacity to monitor the movements of both adult and sub-adult cuttlefish in their natural environment will facilitate identification and understanding of ontogenic changes in behaviours and migratory patterns of wild populations. Our results highlight the potential of electronic tagging methods as tools to aid conservation and management of this important commercial fishery species in the future.