DISCing in Villefranche
by Jean-Olivier Irisson, on
This year's main goal is the study of the orientation capabilities of fish larvae and how those can influence their dispersal by ocean currents. This work started earlier through the internships of several students and the cooperation of researchers at LOV and RSMAS. This cooperation was made more concrete when Claire Paris, from RSMAS, flew to Villefranche to participate in field work. The goal was to deploy the Drifting In Situ Chamber (DISC) instrument, two copies of which were in Villefranche, to study the orientation of as many species as possible.
It was a very intense time (although the pictures might not do justice to the amount of work) but also very productive. We collected orientation data but also swimming speeds for two species: Diplodus annularis (a sea bream) and Oblada melanura (the saddled seabream). Both species are abundant in the area and fished by the local, traditional fishery. That meant 85 deployments of the DISC over a several days. The weather was not necessarily our best ally so achieving this number was kind of a feat in itself. But we had a few good weather days, with plenty of fish larvae, as you can see below, and we made the most out of them.
Now the data is collected, stored, backed up and being processed. We hope to get the results by the end of the summer.
The downtimes (the bad weather days) were opportunities to discuss the future of the project with Claire. We came to the conclusion that doing similar experiments at night would be the best next step, because most of these species actually recruit on the coast during the night.
Claire is also co-supervising Robin Faillettaz PhD thesis and we took advantage of her being here to hold a very productive thesis committee. Robin had the opportunity to present his work so far, most of which done in the framework of this PUF-funded project, and to outline the last year of his PhD. The committee gave very useful comments and advice for the future. In particular, a more detailed inspection of the dynamics of fish recruitment, during the night. But more on that later…