Study

Franciscana bycatch is not reduced by acoustically reflective or physically stiffened gillnets

  • Published source details Bordino P., Mackay A.I., Werner T.B., Northridge S.P. & Read A.J. (2013) Franciscana bycatch is not reduced by acoustically reflective or physically stiffened gillnets. Endangered Species Research, 21, 1-12

Actions

This study is summarised as evidence for the following.

Action Category

Use stiffened materials or increase tension of fishing gear

Action Link
Marine and Freshwater Mammal Conservation

Use acoustically reflective fishing gear materials

Action Link
Marine and Freshwater Mammal Conservation
  1. Use stiffened materials or increase tension of fishing gear

    A controlled study in 2009–2010 of a pelagic area in the South Atlantic Ocean, off the coast of Buenos Aires, Argentina (Bordino et al. 2013) found that using stiffened fishing nets did not reduce the number of Franciscana dolphin Pontoporia blainvillei entanglements compared to conventional nets. Entanglement rates of Franciscana dolphins did not differ between stiffened and conventional nets (both 0.08 dolphins/haul). Catch rates of the three main target fish species also did not differ between net types (whitemouth croaker Micropogonias furnieri, striped weakfish Cynoscion guatucupa, king weakfish Macrodon ancylodon; see original paper for data). Monofilament nylon gill nets of two types (nets made from a stiff grade of nylon and conventional nets; number of each not reported) were deployed in 150 locations by a fishery. The nets were sampled 1–19 times resulting in 273 hauls of stiffened nets and 279 hauls of conventional nets. An observer on board each of three fishing vessels retrieving the nets recorded the number of entangled dolphins within each of 552 hauls between October 2009 and March 2010.

    (Summarised by: Anna Berthinussen)

  2. Use acoustically reflective fishing gear materials

    A controlled study in 2009–2010 of two pelagic areas in the South Atlantic Ocean, off the coast of Buenos Aires, Argentina (Bordino et al. 2013) found that fishing nets made from an acoustically reflective material (barium sulfate) had a similar number of Franciscana dolphin Pontoporia blainvillei entanglements to conventional nets. Entanglement rates of Franciscana dolphins did not differ significantly between barium sulfate nets (0.1 dolphins/haul) and conventional nets (0.08 dolphins/haul). Catch rates of the three main target fish species also did not differ (whitemouth croaker Micropogonias furnieri, striped weakfish Cynoscion guatucupa, king weakfish Macrodon ancylodonalso; see original paper for data). Monofilament nylon gill nets of two types (nets infused with barium sulfate and conventional nets; number of each not reported) were deployed in 150 locations across two fishing areas. The nets were sampled 1–19 times resulting in 255 hauls of barium sulfate nets and 279 hauls of conventional nets. An observer on board each of three fishing vessels retrieving the nets recorded the number of entangled dolphins within each of 534 hauls between October 2009 and March 2010.

    (Summarised by: Anna Berthinussen)

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