Install exclusion devices on fishing gear: Snakes & lizards

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • One study evaluated the effects of installing exclusion devices on fishing gear on snake and lizard populations. This study was in Australia.





  • Unwanted catch (1 study): One replicated study off the coast of Western Australia found that exclusion grids did not prevent sea snakes from entering trawl nets.

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 replicated study in 2012 in off the coast of Western Australia (Wakefield et al. 2017) found that exclusion grids with escape hatches (‘bycatch reduction device’) did not prevent sea snakes from entering the codend of trawl nets in a tropical teleost fishery. In total 331 of 351 sea snakes passed through the exclusion grid, however only 16 sea snakes were recorded as trawl catch. The authors note that sea snakes were observed escaping through the trawl net and may have done so after passing through the grids. Loss of commercially-targeted teleost species from all trawls was 1% of catch. In June–December 2012, catch (target and unwanted) from three commercial trawl vessels was monitored using in-net and onboard cameras during daylight. Vessels were fitted with either: upward-facing grid and escape hatch with diamond-mesh net (372 trawl hours on 2 vessels), downward-facing grid and escape hatch with diamond-mesh net (559 trawl hours on 2 vessels), or downward-facing grid and escape hatch with square mesh net (389 trawl hours on 1 vessel; see original paper for all specifications). Use of bycatch reduction grids with escape hatches was mandatory in this fishery from 2006.

    Study and other actions tested
Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

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Reptile Conservation

This Action forms part of the Action Synopsis:

Reptile Conservation
Reptile Conservation

Reptile Conservation - Published 2021

Reptile synopsis

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