Reducing incidental mortality of Franciscana dolphin Pontoporia blainvillei with acoustic warning devices attached to fishing nets

Published source details Bordino P., Kraus S., Albareda D., Fazio A., Palmerio A., Mendez M. & Botta S. (2002) Reducing incidental mortality of Franciscana dolphin Pontoporia blainvillei with acoustic warning devices attached to fishing nets. Marine Mammal Science, 18, 833-842.
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This study is summarised as evidence for the following.

	Action	Category
	Use acoustic devices on fishing gear Action Link

Use acoustic devices on fishing gear

A replicated, randomized, controlled study in 1999–2000 of multiple pelagic sites in the South Atlantic Ocean, off the coast of Buenos Aires, Argentina (Bordino et al. 2002) found that fishing nets with active acoustic devices attached had fewer entanglements of Franciscana dolphins Pontoporia blainvillei than nets with inactive acoustic devices. Entanglement rates of Franciscana dolphins were lower in fishing nets with active acoustic devices attached (0.002 dolphins/m²/hour) than in nets with inactive acoustic devices (0.01 dolphins/m²/hour). However, South American sea lions Otaria fivescens damaged fish more in nets with active than inactive devices (see original paper for data). Catch rates of target fish did not differ between nets (active devices: 2.2 kg/m²/hour; inactive devices: 2.3 kg/m²/hour). Between October 1999 and February 2000, a total of 604 gill nets with acoustic devices attached (Dukane NetMark 1000, spaced 50 m apart) were deployed on the ocean bottom at multiple sites (number not reported). Each of 604 nets was randomly assigned as a treatment (active acoustic devices emitting pulses every 4 seconds with a peak frequency of 10 kHz; 309 nets) or control (inactive silent acoustic devices; 295 nets). Observers on board the fishing vessels recorded fish catches, entangled dolphins and sea lion damage as each of the 604 nets was retrieved.

(Summarised by: Anna Berthinussen)