Premiers essais de production de larves in vitro chez A sturio

[Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARE [Coll_IRSTEA]Irstea Bordeaux, étude n°150Obtention d'ovocytes ovulés in vitro. Fécondation in vitro, production de larves

Swimming activity responses to water current reversal support selective tidal-stream transport hypothesis in juvenile thinlip mullet Liza ramada

International audienceSwimming activity of thinlip mullet Liza ramada in response to water current reversal was investigated experimentally. A total of 130 young of the year thinlip mullet ranging in size from 22 to 36 mm were entered in trials with four different conditions over three weeks. The fish were subjected to current reversal (6.2/6.2 h) and a LightDark cycle (12/12 h). Swimming direction (with or against the current) was videorecorded throughout the experiments. The mullet showed an effective synchronisation of their swimming activity to water current reversal and LightDark cycle. This synchronisation could demonstrate the existence of a diurnal selective tidal-stream transport in the natural environment as observed in the two other European catadromous species

Alternative flood tide transport tactics in catadromous species: Anguilla anguilla, Liza ramada and Platichthys flesus

International audienceFlood Tide Transport (FTT) was investigated using experimental annular flumes and analysed by Maximum Entropy Spectral Analysis (MESA) to compare 3 species which use FTT: thinlip mullet Liza ramada, European eel Anguilla anguilla and European flounder Platichthys flesus. Juvenile fishes were submitted to experimental conditions simulating estuarine conditions in order to induce a behavioural rhythm which can be deemed comparable to FTT. MESA highlighted several behavioural rhythms within the same time series. The three species exhibited tidal rhythms in relation to time of day of migration, social behaviour and behaviour during ebb-tides. We hypothesise that ecological and morphological traits could induce these behaviours and indicate that it is possible to predict FTT variations for all catadromous species using diet ecology and morphology