JUVENILE STURGEON (ACIPENSER STURIO) HABITAT IN THE GIRONDE
ESTUARY AS DETERMINE BY ACOUSTIC TELEMETRY
M. Lepage, C. Taverny, S. Piefort, P. Dumont, E. Rochard and L. Brosse
The home range of young European sturgeon Acipenser sturio, an endangered species,
was determined in the Gironde estuary using acoustic telemetry. Between May and
August 1999, sixteen young sturgeon aged 4 to 5 years (Total length: 82-122 cm,
Weight: 2.35-8.10 kg) were captured by a trawl and fitted with a coded ultrasonic
transmitter. Manual tracking and monitoring campaigns were conducted over 2 to 3
days a week until November 1999. Diritchlet Tessellation and Minimum Convex
Polygon were used to define the home range of the young sturgeon in the estuary.
Sturgeon movements were observed over period of six hours whether during day or
night. No significant behavioral differences were observed between daytime and nighttime. Most of the movements observed occurred in the same direction than the tidal
current and were oftenly slower than it. Only few lateral movement were observed and
young sturgeon tended to stay in a congregating area (a maximum of 6 fish were
identified at a given moment) located in the middle of the estuary, with an average
depth of 7 m where polychetes worms, their favorite prey, are very concentrated.