Fit rigid (as opposed to mesh) escape panels/windows to a trawl net

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

Study locations

Key messages

  • One study examined the effects of fitting rigid escape windows/panels to trawls for fish escape on marine fish populations. The study was in the Baltic Sea. 





  • Reduction of unwanted catch (1 study): One replicated, paired, controlled study in the Baltic Sea found that fitting rigid escape windows in a section of trawl net reduced the catch of unwanted flatfish compared to a trawl net without escape windows.

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 2013 of an area of seabed in the western Baltic Sea (Santos et al. 2016) found that a trawl net modified with rigid escape windows in a section of net mounted in front of the codend, reduced the catches of unwanted flatfish compared to a trawl net without rigid escape windows. Total catches of plaice Pleuronectes platessa were 56% lower and flounder Platichthys flesus 62% lower in the modified trawl compared to standard trawl (windows: 1,033–1,310 fish, no windows: 2,354–3,437 fish). There was no significant difference in overall catches of the commercial target species, cod Gadus morhua, in the modified and standard trawls (windows: 1,602 fish, no windows: 1,824 fish) or of undersized cod (windows: 255 fish, no windows: 377). Catch comparison trials were done in March 2013 on a commercial twin trawler on cod fishing grounds west of the island of Bornholm. A total of 12 paired trawl deployments were completed using one modified trawl and one standard trawl net. Both nets were identical and fitted with a mandatory design of selective codend of large square mesh (“Bacoma”). In the modified trawl, rigid grid-like escape windows of 38 mm horizontal bar spacing were incorporated in the two side panels of a four-panel net extension piece in front of the codend (“FRESWIND” system - see paper for specifications). Catches from each haul were weighed by species, and the total length of all fish measured.

    Study and other actions tested
Please cite as:

Taylor, N., Clarke, L.J., Alliji, K., Barrett, C., McIntyre, R., Smith, R.K., and Sutherland, W.J. (2021) Marine Fish Conservation: Global Evidence for the Effects of Selected Interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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Marine Fish Conservation

This Action forms part of the Action Synopsis:

Marine Fish Conservation
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