Questioning the effectiveness of technical measures implemented by the Basque bottom otter trawl fleet: Implications under the EU landing obligation

  • Published source details Alzorriz N., Arregi L., Herrmann B., Sistiaga M., Casey J. & Poos J.J. (2016) Questioning the effectiveness of technical measures implemented by the Basque bottom otter trawl fleet: Implications under the EU landing obligation. Fisheries Research, 175, 116-126.


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 replicated, controlled study in 2011 of bottom fishing grounds in the southern Bay of Biscay, France (Alzorriz et al. 2016) reported that bottom trawl nets fitted with square mesh escape panels did not increase the overall escape of undersized catch of three of three fish species, relative to those escaping from the codend. Data were not statistically tested. For fish under the minimum legal size that entered the net, the square mesh panel allowed 0.7% of hake Merluccius merluccius, 11.9% of poor cod Trisopterus minutus and 0.9% of striped red mullet Mullus surmuletus to escape, while 47.3% of undersized hake, 71.4% of undersized poor cod and 53.9% of undersized red mullet escaped through the meshes of the codend. Data was collected from 15 trawl deployments on a research survey in November-December 2011. A trawl codend of 70 mm diamond mesh fitted with one 100 mm square mesh panel located 13 m from the codend was tested (see paper for specifications). Covers installed over the panel and codend collected escaping fish. Fish in both the cover and codend were identified, counted and lengths measured.

    (Summarised by: Leo Clarke)

Output references
What Works 2021 cover

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, 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 21

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 ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust