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 Maria Friederike, Brooks, Mollie Elizabeth, Bilgin, Sabri, Özdemir, Süleyman, Kindt-Larsen, Lotte, Larsen, Finn, Stepputtis, Daniel
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Bycatch; Gillnet modification; Phocoena phocoena; Turbot fishery; Raja clavata; /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; name=SDG 14 - Life Below Water; Lied; Turbot
• Online Access: https://orbit.dtu.dk/en/publications/cd569778-bec6-40a4-8ae9-5394700442a5; https://doi.org/10.1016/j.fishres.2021.106088

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 ).