Acipenser sturio recovery research actions in France

Abstract

International audienceThe European Atlantic sturgeon Acipenser sturio, formerly present throughout Europe, is currently represented by a very critically endangered population in the Gironde-Garonne-Dordogne basin in France. In spite of its protected status in France since 1982, the relict population has continued to decline. Better knowledge of its biology and ecology has been acquired with regard to potential spawning grounds, migrations both downstream into the estuary and on the continental shelf, strength of the last representative cohorts in the estuary, the inhabited area and feeding habits in the Gironde estuary, adaptation of stocked fish to the wild, and characteristics of wild brood fish (frequency, date, sex, reproductive status). Due to the dramatic decline in brood fish by-catch, only four artificial reproductions were successful between 1981 and 2006, the last taking place in 1995. This was the first opportunity to grow larvae and to mark fingerlings for stocking. From the early 1990s, brood-stock building appeared to be the only way to potentially produce fingerlings on a regular basis. As there were no references in either husbandry or related ecophysiology standards, a precautionary strategy was adopted. The most critical environmental factors are salinity, temperature, and light regime. Some encouraging results (semen with motile spermatozoa) were recorded from reconditioned adult males held in brackish water. Some females initiated only partial ovarian development and therefore we introduced some changes, especially in the temperature regime. Complementary investigation and data have been forthcoming through European cooperation on husbandry, feeding, genetics, and endocrinology and this will be developed. Further actions are briefly presented