Study

Selective characteristics of a shark-excluding grid device in a Mediterranean trawl

  • Published source details Brčić J., Herrmann B., De C.F. & Sala A. (2015) Selective characteristics of a shark-excluding grid device in a Mediterranean trawl. Fisheries Research, 172, 352-360.

Actions

This study is summarised as evidence for the following.

Action Category

Fit a size-sorting escape grid (rigid or flexible) to a prawn/shrimp trawl net

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

    A replicated study in 2012 of a seabed area in the Tyrrhenian Sea, western Mediterranean (Brčić et al. 2015) found that a prawn trawl fitted with a rigid size-sorting escape grid allowed a small proportion of unwanted blackmouth catshark Galeus melastomus of larger size to escape capture. In number, 182 catshark escaped through the grid, 263 escaped from the codend and 540 were retained in the codend. Catshark larger than 45 cm total length were more likely to escape through the grid and the estimated length at which half would escape was 53 cm, whereas individuals smaller than 20 cm were more likely to escape from the codend (data reported as probability/selection curves). In addition, for two of two commercial species, the grid-fitted trawl codend retained 39% and 94% of greater forkbeard Phycis blennoides and Norway lobster Nephrops norvegicus respectively. A conventional (50 mm diamond mesh codend) commercial bottom trawl net used in Mediterranean was fitted with an aluminium “Super Shooter” grid with 90 mm bar spacing, located 3.5 m in front of the codend at a 45° angle. Data were collected from six trawl deployments in April and July 2012. Two covers with 20 mm mesh were attached over the grid escape opening and the codend to collect escaped individuals. Total catch was sorted and weighed and fish lengths recorded.

    (Summarised by: Leo Clarke)

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