Efficacy of selective devices in reducing discards in the Nephrops trawl fishery in the Bay of Biscay

  • Published source details Nikolic N., Diméet J., Fifas S., Salaün M., Ravard D., Fauconnet L. & Rochet M. (2015) Efficacy of selective devices in reducing discards in the Nephrops trawl fishery in the Bay of Biscay. ICES Journal of Marine Science, 72, 1869-1881.


This study is summarised as evidence for the following.

Action Category

Fit mesh escape panels/windows to a trawl net

Action Link
Marine Fish Conservation
  1. Fit mesh escape panels/windows to a trawl net

    A before-and-after study in 2003–2012 of bottom fishing grounds in the Bay of Biscay off France (Nikolic et al. 2015) found that following the introduction of prawn trawl nets fitted with top square mesh escape panels and in combination with one additional modification (either a bottom square mesh escape panel, a flexible escape grid, or an increased codend mesh size), did not typically affect the amount of unwanted hake Merluccius merluccius caught. None of the trawl modifications, individually or in combination, affected the weight, number or length of hake caught (data reported as statistical model results). The percentage of hake discarded was 61–78% in the period before trawl regulations were introduced (2003–2005), and 31–72% in the period after its introduction (2006–2012). Total hake discard weight was 1.2–2.7 thousand tonnes before and 0.5–2.8 thousand tonnes after the regulations. Standardised length of hake caught before and after the regulations was 8–9 cm and 7–11 cm respectively. In addition, effects on target catches were variable but modifications typically reduced catches of undersized Norway lobster Nephrops norvegicus. From 2005, all Nephrops trawls nets were required to fit a 100 mm square mesh panel in the upper codend to allow escape of hake. In 2008 vessels catching >50 kg of Nephrops a day were required to include at least one additional measure to reduce undersized Nephrops catches: a 60 mm square mesh lower panel; a 13 mm flexible grid in the codend; or an 80 mm codend (increased from 70 mm). Data from on-board fisheries observers were analysed for the period 2003–2012, before and after the regulations were implemented.

    (Summarised by: Leo Clarke)

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