Tropical ecosystems of the high seas

Tunas : species found in every ocean  |  The Indian Ocean, a major site 
Fish Aggregating Devices  |  Habitat occupation by large pelagics  
Interactions between the resource and fishers  |  The joint effects of fishing and climate  |  Knowledge integration through ecosystem models

ecosystemes

Over the last 30 years, the offshore marine domain has become one of the major objects of study in the global oceanographic community. A considerable effort to integrate physical, geochemical and biological knowledge has been recently accomplished through the development of  systems of observation, both remote (satellites) and in situ, and the parallel development of models linking climate, ocean physics, geochemistry and biology. The stakes concerning this oceanic research on the future of human societies are real. On the one hand, the ocean plays a regulatory role in the planet’s climate: it intervenes on the forefront of climate change scenarios, whose consequences can be disastrous for certain insular or waterfront populations. On the other hand, the living resources within it have been increasingly exploited since the middle of the XXth century.
Prior to the Second World War, the only offshore pelagic species to be truly exploited were limited to the large cetaceans, and tuna stocks were then in a virgin state. Since then, industrial fleets of longliners and seiners have been deployed in all oceans, and catches of tuna and tuna-like fish now exceed 5 million tons. This development is explained by the fact that tuna constitutes a high merchant-value resource, supported by growing world markets. Although stocks have been strongly depleted, yields have remained stable due to ever-more efficient technological adaptations. In the face of the largely recognized overexploitation of predators, what is likely to happen in the middle term in regard to fisheries and ecosystems? The evaluation of the impact of fisheries on the future of these resources, and more broadly on the structure and functioning of the ecosystems of the high seas, is therefore a pertinent objective. The research carried out by IRD and its partners concerns the ecosystems of the high seas and tropical tuna fisheries. Although ecosystems are considered as a whole, the accent is placed more particularly on the higher predators. Tunas are the target group, but other species will also be studied, from small pelagics to sharks, including seabirds, dolphinfishes and swordfishes.

consommation de poissons
consommation de poissons
consommation de poissons
consommation de poissons