The diet of the cuttlefish Sepia officinalis L. (mollusca : cephalopoda) during its life cycle in the Northern Bay of Biscay (France)

The diet of the cuttlefish Sepia officinalis L. was studied from stomach co ntents. This analysis was carried out on monthly samples throughout the who le biological cycle in the Northern Bay of Biscay focusing on 3 areas: a br eeding and hatching area (Morbihan Bay), a winter area (off Belle-Ile islan d) and a transition area (Morbraz). The list of prey species showed that Sepia officinalis an opportunistic pre dator with a flexible diet that allows it to survive when its usual prey is unavailable. The diet is discussed in terms of the repletion ratio (R.R.: number of stom achs with remains/number of stomachs examined as %) and the monthly frequen cy of a prey species. Results show that R.R. was minimal during reproductio n (around 25%) whereas during the rest of the life cycle it was higher than 50%. Amphipods (Phtisica marina) are the main prey for the first 3 months. During the growth period, fish (Ammodytiae, Gobiidae, Gadidae) occupied th e first place in the diet. In animals returning to coastal waters for repro duction, the diet changed again and crustacea especially Brachyura (Carcinu s maenas, Liocarcinus arcuatus) became the most important prey.