The effect of Nordmøre grid length and angle on codend entry of bycatch fish species and shrimp catches

• Published in: Canadian journal of fisheries and aquatic sciences 2019-02, Vol.76 (2), p.308-319
• Main Authors: Larsen, Roger B, Sistiaga, Manu, Herrmann, Bent, Brinkhof, Jesse, Tatone, Ivan, Santos, Juan
• Format: Article
• Language: English
• Subjects: Agriculture and fishery disciplines: 900; Body size; Bycatch; bycatch reduction; Decapoda; Design and construction; Equipment and supplies; Fish; Fisheries; Fisheries science: 920; Fishery conservation; Fishery research; Fishing; Fishing gear; Fishing nets; Fiskerifag: 920; Gadus morhua; Gear construction; grid angle; grid length; Haddock; Hippoglossoides platessoides; Juveniles; Landbruks- og Fiskerifag: 900; Layers; Marine; Melanogrammus aeglefinus; Pandalus borealis; Redfish; Restaurants; Sebastes; Shrimp fisheries; Shrimp trawl; Shrimping; size selectivity; Trawling; Trawlnets; VDP
• ISSN: 0706-652X; 1205-7533; 1205-7533
• DOI: 10.1139/cjfas-2018-0069

The Nordmøre grid is regarded as an efficient bycatch-reducing device and is used in various shrimp trawl fisheries globally. However, in some shrimp fisheries, bycatch remains a problem that seriously impacts commercial trawl activities. This study tested and compared the performance of two versions of the Nordmøre grid in the northeast Arctic deepwater (northern) shrimp (Pandalus borealis) fishery, a standard version with an operating angle of approximately 45° and a longer version of the grid (40% longer) with an operating angle of approximately 30°. The grid passage probability for the bycatch of juvenile cod (Gadus morhua), haddock (Melanogrammus aeglefinus), American plaice (Hippoglossoides platessoides), and redfish (Sebastes spp.) increased significantly for certain size ranges of fish when using the longer grid. The longer grid also resulted in a significant increase in grid passage probability for large shrimp. Previous studies have reported that a reduced operating angle can lead to a lower grid passage probability for bycatch fish species and shrimp; however, the results of the current study demonstrate that a longer Nordmøre grid more than compensates for the reduced operational angle.