Fit a funnel (such as a sievenet) or other escape devices on shrimp/prawn trawl nets

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

Study locations

Key messages

  • One study examined the effects of fitting a funnel, sievenet, or other escape devices on trawl nets on marine subtidal invertebrate. The study was in the North Sea (UK).




  • Unwanted catch abundance (1 study): One replicated, paired, controlled study in the North Sea found that trawl nets fitted with a sievenet appeared to catch fewer unwanted catch of non-commercial invertebrates compared to unmodified 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, paired, controlled study in 2006–2007 in the North Sea, off the east coast of England, UK (Catchpole et al. 2008) found that trawl nets used in shrimp/prawn fisheries fitted with a sievenet (funnel-like device) appeared to catch fewer unwanted non-commercial invertebrates (discard) compared to unmodified nets. Differences were not statistically tested. Of the seven invertebrate discard species recorded, six tended to be caught in lower numbers in nets fitted with a sievenet compared to nets without (28–83% reduction in numbers caught), and one species tended to be caught in equal numbers. Use of selective gear to reduce unwanted catch in the brown shrimp fishery was made compulsory in 2003 in the European Union. Between January 2006 and January 2007, abundances of unwanted invertebrate species were compared in nets with a sievenet and without. Nets were deployed in pairs (one sievenet; one unmodified net) during 98 hauls for 1h. All organisms were identified, sorted as commercial catch or discard, and counted.

    Study and other actions tested
Please cite as:

Lemasson, A.J., Pettit, L.R., Smith, R.K. & Sutherland, W.J. (2020) Subtidal Benthic Invertebrate Conservation. Pages 635-732 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Subtidal Benthic Invertebrate Conservation

This Action forms part of the Action Synopsis:

Subtidal Benthic Invertebrate Conservation
Subtidal Benthic Invertebrate Conservation

Subtidal Benthic Invertebrate Conservation - Published 2020

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