Seahorse behaviour and aquaculture: How to improve Hippocampus guttulatus husbandry and reproduction?

Abstract

In recent years, aquaculture development has been based on the use of new tools and technologies from different scientific areas. Animal behaviour can also constitute a useful tool for aquaculture and contribute to the improvement of rearing protocols. In this study, a behavioural approach was developed for the long-snouted seahorse ( Hippocampus guttulatus) culture, in order to improve broodstock husbandry and reproduction. The optimisation of laboratory conditions (such as water column depth, holdfast type and availability, animal density, sex ratio and male/female size) was analysed based on seahorse behaviour. Social and reproductive behaviours were studied in terms of space use preferences, activity levels, distribution patterns, mate competition and selection, courtship, male pregnancy and juvenile birth. In captive conditions, seahorses were diurnally active and more isolated during the night. They were mainly located in the water inlet area, near the bottom, and preferred vertical holdfasts and natural plants. H. guttulatus reproduction in captivity was achieved. Seahorse behaviour and reproductive output were affected by the different rearing conditions but not animal welfare. Animal density increased seahorse activity and influenced the number of groups, while holdfast availability affected the group size. Seahorses were generally found in male–female pairs that were not stable over time and tend to select similar size or larger mates. Male competition was rather frequent and was affected by the sex ratio. Courtship occurred during all day and no daily greetings were observed throughout male pregnancy. Water column depth and male competition resulted in mating interruption and juvenile number and size decreased in artificial conditions. Animal behaviour demonstrated to be important for the improvement of seahorse husbandry and reproduction and to constitute a potential tool for aquaculture development.