REseau MOllusques des Rendements Aquacoles huitre creuse (REMORA) ; Résultats des stations nationales. Année 1999

The monitoring network IFREMER /REMORA is assessing, on a yearly basis, mortality, growth and quality criteria of two oyster batches ("juveniles" = one-year old ; and "adults" = two-years old), distributed among various stations of the main French oyster areas. Samplings are carried out in February, June, September and December (late November in 1999). This network is a tool for trend estimations (geographic and chronological, on the national scale) ; it must not be considered as an accurate estimation of professional oyster ongrowings. Based on REMORA results, generally tallied with professional observations, and with comparison to previous years, 1999 exhibited mortality in adults (23%) and poor growth in both adults (63.0 g in late November) and juveniles (27.3 g). However, as usual, results differed widely from one station to the other. The lowest mortality rates were observed in bay of Quiberon, in Vendée and in Arcachon. Although better than 1998, the year 1999 displayed low growth, mainly because of a lack of growth in Autumn, especially along the Atlantic coast from Pen-Bé to Marennes. This lack of growth induced poor quality indices, with several stations in the lowest class of the Afnor classification, which have been very rare in the network history, since 1993. The infestation of the worm Polydora. in oysters was still increasing, and very few areas remained lowly infested in both adult and juvenile oysters. The infestation in juveniles spread out in spring in Normandy, and in summer in the other areas. The evolution in autumn was more variable. A specific report will be written on this subject.