Innovative Solution for Coastal Fish Nursery Restoration

The post-larval stage is the final stage of the pelagic larval phase in the life cycle of reef-dwelling coastal marine animals. These fish settle in shallow habitats to protect themselves from predation. In intact onshore habitat, more than 90% will naturally die within the first week of their return, but without natural habitats, the survival rate can decline to zero! Young-of-the-Year gathered in shallow habitats seek nurseries, defined as possessing three attributes: 1-presence of congeners (high-density), 2-presence of food, 3-presence of calm water and refuge which limit predation and allow growth. Unfortunately for young recruits, human coastal infrastructures are increasingly prevalent, directly affecting their habitats. Mitigation for the impacts is crucial to restore connectivity and life cycles of aquatic populations.

Various artificial micro-habitats called Biohut® have been introduced to damaged areas as a substitute for the role played by rocky sea bottoms protecting post-larval. The double cage system creates a predator-free habitat with adapted food. In 2013 & 2014, a large-scale deployment of the Biohut® was implemented in six French harbors and was monitoring (Under-Water-Visual-Census) by researchers from University of Perpignan. The presentation highlights the first promising assessment of Biohut® in terms of fish, mobile fauna and fixed fauna/flora biodiversity.