Fit one or more soft, semi-rigid, or rigid grids or frames to trawl nets and use square mesh instead of a diamond mesh at the codend

How is the evidence assessed?
  • Effectiveness
    70%
  • Certainty
    20%
  • Harms
    0%

Study locations

Key messages

  • One study examined the effects of fitting one or more soft, semi-rigid, or rigid grids or frames to trawl nets and using a square mesh codend on subtidal benthic invertebrates. The study was in the Gulf of St Vincent (Australia).

 

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (1 STUDY)

  • Unwanted catch abundance (1 study): One replicated, paired, controlled study in Gulf of St Vincent found that trawl nets fitted with a rigid U-shaped grid and a square-oriented mesh codend reduced the catch rates of three dominant groups of unwanted invertebrate catch species, compared to unmodified nets.

OTHER (1 STUDY)

  • Commercial catch abundance (1 study): One replicated, paired, controlled study in the Gulf of St Vincent found that trawl nets fitted with a rigid U-shaped grid and a square-oriented mesh codend reduced the catch rates of the commercially targeted western king prawn, due to reduced catch of less valuable smaller-sized prawns, 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 2012 in the Gulf of St Vincent, off the coast of South Australia (Gorman & Dixon 2015) found that trawl nets fitted with a rigid U-shaped grid (“bycatch reduction device”) and a square-oriented mesh codend resulted in lower catch rates of three dominant groups of unwanted invertebrate catch species, compared to unmodified nets. Compared to unmodified nets, the modified nets led to a 92% decrease in catch rate (kg/h) of sponges, 78–82% decrease in catch rate of crabs and other crustaceans, and a 61% decrease in catch rate of molluscs (excluding commercially valuable species of octopus, squid and cuttlefish; raw data not provided). A 15% decrease in catch rates of the commercially targeted western king prawn Penaeus latisulcatus was recorded due to reduced catch of less valuable smaller-sized prawns. In May 2012, unwanted catch of invertebrates in modified and unmodified nets were compared (see paper for details). Nets were deployed by four vessels during 29 paired hauls for 30 min (one modified; one unmodified; side-by-side simultaneously). All invertebrates were identified, sorted as commercial prawn catch or unwanted catch, and weighed.

    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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