Artificial surfaces for cuttlefish eggs ( Sepia officinalis L.) in Morbihan Bay, France

From March to September, cuttlefish lay eggs on natural substrata (tubes of polychaetes, Zostera leaves, algae) and also on artificial surfaces (cuttletraps, ropes, branches). In Morbihan Bay, during this period, between 18 and 40 million eggs are laid on cuttletraps. From March to May, fishermen empty traps every two days. They stack the traps on a pontoon-bridge before further use, and so a great quantity of eggs are destroyed. The objective of this study is provide artificial substrata (similar to natural surface) to compensate for significant loss of eggs. The artificial surfaces, in the form of floating ropes, are well adapted to the hydrodynamics of Morbihan Bay. The characteristics of the ropes best suited for egg laying are a diameter about 8 mm and a length between 30 and 90 cm with a preference for 50 cm. The number of eggs per surface is estimated at 2200, and the surfaces should be easy to manipulate by fishermen.