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405 - The new face of El Niño
May 2012
El Niño is changing. This climatic troublemaker is increasingly appearing in a form known as Modoki, Japanese for 'similar but different'. The heart of the phenomenon is moved from the eastern tropical Pacific towards the centre of the Pacific basin. New research conducted by the IRD and its partners from the Legos( 1) laboratory details the biological aspects of Modoki in the equatorial zone. Such events reduce the levels of phytoplankton in the central Pacific area: Satellite images analysed between 1997 and 2010 show the ocean to be less green during the events of 2002-2007 and 2009-2010. This colouring demonstrates reduced levels of surface marine algae, synonymous with a low level of biological activity.
Another study conducted with Peruvian( 2) researchers and those from the Locean( 3) laboratory has revealed that Modoki, inversely to its larger cousin, might be responsible for upwelling( 4) the length of the South-American coastline. A high resolution oceanic model, linked to satellite and historic data from Imarpe( 5), indicates that recent episodes have seen an increase in this rising cold water, rich in nutrients. The predicted increase in frequency of Modoki( 6) events could thus influence fishing in the zone.
404 - Marine protected areas : what is their impact on fishing?
May 2012
In 2005, there were more than 5,000 marine protected areas across the globe. These reserves assist in preserving biodiversity. And yet, the impact on fishing has not yet been demonstrated. The Amphore( 1) programme, coordinated by the IRD and involving French and West African laboratories, provides a detailed economic and biological survey. Four reserves of varying size and age were studied in closer detail, including two in West Africa: one in Senegal, the other in Mauritania. A ban on fishing operations within protected areas only gives rise to a small increase in the total fish biomass, although there is an improvement in population diversity. The observations and models carried out by researchers show that halieutic resources are greater outside of protected areas, in zones that can be exploited by fishermen. The larger the area of the reserve, the more positive the effect. However, the creation of vast protected areas can cause problems, particularly in heavily anthropized areas, and requires participatory management.
