Characterization of summer mortalities of C. gigas oyster in France in relation to environmental parameters
Field characterization of summer mortality was performed in France in the frame of the Morest project. Natural and hatchery spat were compared between three oyster production areas in France. Regardless of the natural or hatchery origin, oysters died during the reproduction period after temperature reaches 19 degree C. Thus, in southern areas, temperature accelerated gametogenesis of small spat (10mm) as well as adults, and mortality appeared for the two age classes. In contrast, sexual maturation proceeded more slowly in northern where spat mortality was lower compared to 18 months old oysters. However, critical gametogenesis and temperature were not sufficient to induce mortalities, as observed in examples with stable environment. Alternatively sediment proximity in addition to oyster manipulations increased mortality during spring and summer, suggesting that some additional environmental stresses were necessary to reproduce the phenomena. These interaction processes will be detailed in the other Morest contributions.
Soletchnik Patrick, Ropert Michel, Bedier Edouard, Costil K. S., Dubois Brice, Degremont Lionel, Bouget Jean-Francois, Martin Jean-Louis, Enriquez-Diaz M., Faury Nicole, Le Moine Olivier, Renault Tristan, Gagnaire Beatrice, Huvet Arnaud, Moal Jeanne, Samain Jean-Francois (2003). Characterization of summer mortalities of C. gigas oyster in France in relation to environmental parameters. 98 Annual Meeting National Shellfisheries Association, Monterey, CA (USA), 26-30 Mar 2006. https://archimer.ifremer.fr/doc/00000/3348/