Estimates indicate that over 80 percent of all prawns caught in Tanzania come from the Rufiji Delta and over 90 percent of all the catch is exported (Mwalyosi, 1990). The biggest cause of biodiversity loss in relation to fishing at a local level is poor fishing gear and practices. For example, local people in Rufiji Delta use stake traps (wando) made from the roots of Rhizophora mucronata. With this technique, fishermen block the large part of a small channel by planting wooden stakes in a V shape so that fish are stranded during low tide. This process is destructive because it affects the roots of the plant and may kill the entire plant. Also, these traps are woven together so tightly that even juvenile fish are trapped. Apart from traps, the use of fishnets with small meshes causes similar problems. This is also common in Ruvu and Wami Deltas. Most fishnets available in the country are imported. Besides being of low quality, they are also prohibitively expensive for most of the fishermen who, as a result, resort to more destructive methods. These practices and technologies are not sustainable and it appears that most fishermen are not aware of the dangers of using them. A final major direct cause of the loss of fish at the local level is the involvement of big trawlers that operate where artisanal fishermen do their fishing.