Using acoustically visible gillnets to reduce bycatch of a small cetacean: first pilot trials in a commercial fishery

• Published in: Fisheries Research
• Main Authors: Kratzer, Isabella, Brooks, Mollie Elisabeth, Bilgin, Sabri, Özdemir, Süleyman, Kindt-Larsen, Lotte, Larsen, Finn, Stepputtis, Daniel
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Text; article; ddc:570; bycatch > gillnet modification > Phocoena phocoena > turbot fishery > Raja clavata; Phocoena phocoena; Turbot
• Online Access: https://doi.org/10.1016/j.fishres.2021.106088; https://www.openagrar.de/receive/openagrar_mods_00077622; https://www.openagrar.de/servlets/MCRFileNodeServlet/openagrar_derivate_00044872/dn064530.pdf

Bycatch of protected species, particularly small cetaceans, in gillnets is a worldwide concern. One hypothesis for this is that echolocating cetaceans entangle because they do not perceive conventional gillnets as impenetrable barriers, owing to the gillnet’s faint echo. A gillnet modified for improved acoustical visibility was tested in a first pilot trial in a commercial gillnet fishery targeting turbot (Scophthalmus maeoticus) on the Turkish Black Sea coast. This study is the first demonstration of the viability of using a gillnet equipped with small acrylic glass spheres to reduce bycatch of harbor porpoises in a commercial fishery and provides the basis for full-scale sea trials of the gear in commercial fisheries through a power analysis. In these pilot experiments, the focus lied on the handling of the gear and identification of requirements for a full-scale trial, but results include promising bycatch data for an endangered echolocating marine mammal (Phocoena phocoena) and no reduction in catch efficiency of a bottom-dwelling, vulnerable species (Raja clavata).