14. Juli 2003 – Institut de recherche pour le développement (IRD)
Acoustical methods are a boon for long-term observation and monitoring of aquatic ecosystems. Human activity has made these environments more vulnerable and research is urgently needed using the most effective techniques available. Coastline habitats are most under threat, the Mediterranean coast being a prime example. The survival of many animal species depends on the state of coastal lagoons and ponds and of estuaries. Acoustics technology and methods have greatly developed over the past 50 years and offers ideal means for conducting detailed investigations.
Acoustics has great scope for finding accurate data on aquatic ecosystems. The techniques available enable fisheries biologists to “see” what is happening in an environment which other study tools especially optical methods, cannot reach. Acoustics can capture features of all aquatic environments and can help build up three-dimensional pictures of marine or freshwater organisms and their habitats. They help in species identification, abundance and distribution (including fish, plankton and algae), determination of size, behaviour and life-cycle stage. Acoustical surveying is also ideal for simultaneous measurement of physical, biological and chemical parameters, for shallow freshwater (lakes, rivers, coasts, lagoons, mangroves) or marine waters, particularly for continental shelf-seas.
As a back-up tool for fisheries, the first function of probes and sonars is to detect and locate fish schools and to assist fishing campaigns. For scientific investigation, they enable biologists to identify species, analyse their behaviour and assess biomass size. Acoustics can therefore provide both pelagic and demersal fish stock estimates, an essential prerequisite for more effective resources management. Thanks to such tools, scientists can supply regulatory bodies of the European Union with information on which to base annually maximum catch sizes and quotas, in the context of the common fishing policy to minimize the risk of overexploitation.
Institut de recherche pour le développement (IRD)