Compte-rendu de la campagne OBSERVHAL98 - Observations à finalité halieutique

The scientific cruise Observhal98 took place in Biscay Bay, May 14 to June 6, 1998, with the submersible Nautile operated from the research vessel Nadir. The goal was to make direct underwater observations on fishes and invertebrates of commercial interest, on the environment in which they live and on the impact of fishing gears. A total of 22 dives, 2 to 5 hours long have been operated, ten by depth 1800 to 1000 m, three by 500 to 200 m, seven by 80 to 200 m and two in the water column. An in situ technic have been developped and operated from the submarine, with the aim of studying the growth scheme of deep water fishes. Specimen of Hoplostethus atlanticus and Trachyscorpia cristualata have been caught, anesthetised, injected with vital coloring and stabulate for 4 weeks. Observations on fishing gears have dealt with tracks of bottom trawls, hake nets, monkfish nets and edible crab pots. Each dive gained observations on the distribution, ecology and behaviour of species as well as on the distribution and abundance of larger marine debris.