Operational modelling of bigeye tuna (Thunnus obesus) spatial dynamics in the Indonesian region

With INDESO, Indonesia has implemented a system for the monitoring and management of its tuna resources. Despite increasing catch, very few is known about the dynamics and real abundance of tuna species in the Indonesian waters and adjacent oceanic regions. The SEAPODYM model was implemented in an operational chain of production for the Indonesian region to simulate tuna spatial dynamics in realtime. This challenging objective imposed developing a global scale model at coarse resolution to provide initial and boundaries conditions of the regional model. A parameter optimization approach was used to provide the best solution fitting several hundreds of thousand catch observations, over a long historical simulation at coarse resolution. Then downscaling method and regional modelling at high resolution (1/12°x day) were validated to produce realtime and forecast on a weekly basis. The architecture of this application, the approach for its parameterization and some key results are presented and discussed.

Kinetics of ethanol metabolism in sheep

Kinetic aspects of ethanol metabolism were studied in sheep after intravenous or intraruminal infusion of ethanol. Vmax and Km in fed animals were respectively 295 +/- 10 mg.h-1.l-1 (l = litre of body water) and 32.1 +/- 2.4 mg.l-1. Elimination half-life was 1.47 +/- 0.26 h. The corresponding values in the fasted animal were not significantly different. During venous infusion an increase in plasma acetate, inversely correlated to plasma ethanol, was observed. No modification in glycemia occurred. Intraruminal infusion of ethanol increased the concentration of all SCFA in the rumen juice, the largest part of this modification being relative to acetate. Repetition of the infusion over a period of 11 consecutive days increased the number of SCFA in the rumen, indicating microflora adaptation to ethanol utilization. Taking into account the range of ethanol concentrations found in silage (10-50 g.kg-1 BW) we can consider that ethanol is readily metabolized simultaneously by the rumen microflora and the enzymatic system of the host. With a corresponding daily intake of ethanol (0.2-1 g.kg-1 BW) both systems are not saturated and plasma ethanol level always remains below 0.25 g.l-1.