Study

The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window

  • Published source details Eigaard O.R. & Holst R. (2004) The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window. Fisheries Research, 68, 99-112

Actions

This study is summarised as evidence for the following.

Action Category

Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net

Action Link
Marine Fish Conservation
  1. Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net

    A replicated study in 2000 of a pelagic area of the North Sea, Scotland (Eigaard & Holst 2004) reported that a fish trawl fitted with a size-sorting escape grid system reduced the catch of non-target whiting Merlangius merlangus and haddock Melanogrammus aeglefinus in an industrial fishery targeting the smaller-sized species Norway pout Trisopterus esmarki, relative to the overall catch. Data were not tested for statistical significance. Catches of whiting and haddock were reduced in weight by 57% and 37% respectively by the grid. Almost all whiting sorted out were above the minimum landing size (23 cm), whereas for haddock the main sizes of the fish sorted out were below the 32 cm minimum landing size (data reported as length frequency distributions). Relative to retained catch, losses of fish above the minimum landing size were estimated as 46% for whiting and 9% for haddock. Catches of the target species Norway pout were reported to be reduced by 7%. Data were collected in November/December 2000 from 27 valid trawl deployments on a major Norway pout fishing area in the northern North Sea. An industrial trawl fitted with a hinged grid of 24 mm bar spacing was inserted in front of the codend. The top of the grid was covered by a square mesh window of 108 mm mesh to retain larger marketable fish (see paper for specifications). Covers attached over the top of the grid and the square mesh window collected escaped fish and fish retained by the window. Sub-samples of fish from the two covers and the codend catch were sorted and weighed and fish lengths measured.

    (Summarised by: Natasha Taylor)

Output references

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, terrestrial mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust