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Acoustic monitoring to document the spatial distribution and hotspots of blast fishing in Tanzania

Braulik, Gill, Wittich, Anja, Macaulay, Jamie, Kasuga, Magreth, Gordon, Jonathan, Davenport, Tim R.B., Gillespie, Douglas
Marine pollution bulletin 2017 v.125 no.1-2 pp. 360-366
acoustics, coasts, coral reefs, explosives, fisheries, monitoring, people, water pollution, Tanzania
Destructive fishing using explosives occurs in a number of countries worldwide, negatively impacting coral reefs and fisheries on which millions of people rely. Documenting, quantifying and combating the problem has proved problematic. In March–April 2015 231h of acoustic data were collected over 2692km of systematically laid transects along the entire coast of Tanzania. A total of 318 blasts were confirmed using a combination of manual and supervised semi-autonomous detection. Blasts were detected along the entire coastline, but almost 62% were within 80km of Dar es Salaam, where blast frequency reached almost 10blasts/h. This study is one of the first to use acoustic monitoring to provide a spatial assessment of the intensity of blast fishing. This can be a useful tool that can provide reliable data to define hotspots where the activity is concentrated and determine where enforcement should be focused for maximum impact.