Some 210 million people live in low elevation areas within 10 km of mangroves and many of these directly benefit from mangrove-associated fisheries. Yet, these people are often unaware of the key role mangroves may play, especially if the associated fisheries are offshore.
A new study by Wetlands International, The Nature Conservancy and the University of Cambridge, launched today at World Fisheries Day, concludes that mangrove conservation and restoration in areas close to human populations will render the greatest return on investment with respect to enhancing fisheries.
The fisheries value of mangroves is site specific as it depends on how many fish a mangrove produces, how many fish are subsequently caught by humans, and then what the fisheries value is, both in economic terms, as a food supply or through the livelihoods that they support.
As demands for fish continues to rise with the increase of coastal populations and rapidly growing economies, understanding where mangrove-associated fish productivity is highest is critical. Well-known species that rely on mangroves in one way or another include crabs, prawns, mullet, herring, anchovy, snappers and groupers.
Fisheries value site specific
The values of fisheries, which can be stated in simple catch statistics, in monetary terms, as a food supply or through the livelihoods that they support, are site specific. The study concludes that fish populations that rely on mangroves will be highest where mangrove biomass productivity is highest, as leaves and woody materials form a key part of the marine food chains.
Fish productivity is also higher where there is high freshwater input from rivers and rainfall and where mangroves are in good condition. The total area of mangrove is clearly important in determining the total numbers of fish, but the length of the mangrove margin is also key, since generally it is the fringes of mangroves where fish populations are enhanced.
For details, please visit www.wetlands.org