Development and testing of fish-retention devices for pots: transparent triggers significantly increase catch efficiency for Atlantic cod (Gadus morhua)

Jérôme Chladek*, Daniel Stepputtis, Andreas Hermann, Peter Ljungberg, Paco Rodriguez-Tress, Juan Santos, Jon Christian Svendsen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Fish pots have lower catch efficiency than gillnets and trwls and, therefore, are rarely used for catching Atlantic cod (Gadus morhua) and similar species. Fish-retention devices (FRDs), non-return devices that permit fish to enter the pot while impending exit, reduce the pot exit rate and therefor can increase catches. Conventional FRDs, however, also reduce entry rate and may not improve catches. To increase pot-catch efficiency, we developed and tested a new trigger-type FRD, made of transparent acrylic glass, which we named acrylic fingers (AFs). AFs are almost invisible underwater and offer little resistance to entering cod. We compared AFs with Neptune fingers (NFs), a conventional trigger-type FRD with a distinct visual outline, by observing cod entry and exit rates through both triggertypes rigged to a pot in a net pen. Both trigger types significantly reduced exit rates compared with a funnel without triggers; however, NFs also reduced entry rates by visually deterring od. Specifically, AFs have higher entry-to-exit ratios and therefore improve catch efficiency. Combining AFs with funnels further increased catch efficiency. Thus, transparent acrylic triggers present a promising new approach to increasing pot-catch efficiency and may increase the uptake of the cod pot, an environmentally low-impact gear. 
Original languageEnglish
Article numberfsaa214
JournalICES Journal of Marine Science
Volume78
Issue number1
Pages (from-to)199-219
Number of pages21
ISSN1054-3139
DOIs
Publication statusPublished - 2021

Keywords

  • Catch efficiency
  • Fish-gear interaction
  • Fish pots
  • Fish-retention device
  • Passive fishing gear
  • Pot entry-to-exit ratio

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