Aquaculture of stalked barnacles (Pollicipes pollicipes)

Abstract

The stalked barnacle, Pollicipes pollicipes, is considered a delicacy on the Iberian Peninsula and has a high market value. Despite being a dangerous activity, increased collection efforts and associated stock shortage have raised awareness of the need for effective conservation and stock management policies. Accordingly, aquaculture has received interest as an alternative to supply the market and for re-stocking programmes. However, knowledge on the aquaculture requirement of this species and applicable production cycles is limited. Research challenges span the entire P. pollicipes life cycle, from adult reproduction to larval settlement. Though adults have been kept in culture, the conditions required for broodstock reproduction and larval release remain poorly studied and larvae have been routinely extracted from wild-collected adults and reared to cyprids. Optimization of larval culture is essential for the production of high-quality larvae and avoidance of high mortality. Furthermore, cyprid settlement on artificial substrata presents a bottleneck to production, with settlement occurring mostly on conspecific adults. The conditions that mediate settlement on preferential substrata have yet to be established. Though juvenile behaviour and growth in the wild have been the subject of ecological studies, research on culture conditions is limited and the influence of environmental factors is poorly understood. In the present work, the effect of environmental conditions on the behaviour and development of P. pollicipes was tested throughout the life cycle to identify optimal culture conditions and assess potential for larger-scale culture. Research focused on broodstock reproductive conditioning, larval culture, larval settlement and juvenile culture and behaviour. Broodstock reproductive conditioning was investigated by monitoring larval production and nauplius quality from adults reared under different temperature regimes. P. pollicipes larvae were also cultured under different conditions of temperature, food quality, photoperiod and salinity, and monitored for growth and survival. Larval attachment and metamorphosis on adults were tested for cyprids of different age and batch, and according to environmental factors such as temperature, salinity, hydrodynamics and light conditions. Optimal conditions were then used for investigating settlement on substrata in culture, and natural and artificial structures were ii tested for settlement in the wild. Juvenile feeding behaviour and performance in culture were investigated in relation to hydrodynamics, temperature, food quality and quantity.