REPHY is a national network covering the coast of the French mainland along with that of three of its overseas departments: Martinique, Guadeloupe and Reunion Island. The aims are as follows: - to observe all phytoplankton species in the coastal waters and to monitor events such as coloured water, exceptional blooms, and the proliferation of species which are toxic or disruptive to marine fauna, - Particularly to monitor species producing toxins which are dangerous to shellfish consumers . These objectives are complementary, as the regular monitoring of all phytoplankton species makes it possible to detect known toxic and invasive species, but also to detect potentially toxic species. It is the presence of these toxic species in the water which triggers the monitoring of toxins in shellfish. The mission of REPHY is to monitor shellfish in their natural environment (such as parks and deposits). For shellfish removed from marine environments (that is to say in shellfish logistics establishments or on markets prior to export), national monitoring and control plans are organised by the General Food Directive at the French Ministry of Agriculture. Analyses are performed by the accredited departmental veterinary laboratories as organised by the National Reference Laboratory from the French Food Safety Agency.

The observation of ecosystems by Ifremer's Fisheries Information System (SIH) is based on a network of sea cruises. It aims to assess the state of stocks of the various species fished in France and Europe. It also enables the characterisation of the marine ecosystem in which the populations evolve. 23 scientific cruises take place each year at sea, enabling data to be collected for more than 30 years for the oldest. Thanks to the use of standardised fishing gear, the data acquired each year on board scientific vessels or professional fishing vessels contribute to the calculation of the index of abundance, with thousands of fish taken during timed trawls. The fish are measured and their age is assessed by measuring their otoliths (small bones located in the inner ear of the fish).