Use stiffened materials or increase tension of fishing gear

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One study evaluated the effects on marine mammals of using stiffened materials in fishing nets. The study was in the South Atlantic Ocean (Argentina).





  • Reduction in entanglements/unwanted catch (1 study): One controlled study in the South Atlantic Ocean found that using stiffened fishing nets did not reduce the number of Franciscana dolphin entanglements.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. 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.

    Study and other actions tested
Please cite as:

Berthinussen, A., Smith, R.K. and Sutherland, W.J. (2021) Marine and Freshwater Mammal Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Marine and Freshwater Mammal Conservation

This Action forms part of the Action Synopsis:

Marine and Freshwater Mammal Conservation
Marine and Freshwater Mammal Conservation

Marine and Freshwater Mammal Conservation - Published 2021

Marine and Freshwater Mammal Synopsis

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