Quantification of species selectivity by using separating devices at different locations in two whitefish demersal trawls

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 66; no. 12; pp. 2052 - 2061
• Main Authors: Holst, René, Ferro, Richard S.T, Krag, Ludvig Ahm, Kynoch, Robert J, Madsen, Niels
• Format: Journal Article
• Language: English
• Published: Ottawa, ON National Research Council of Canada 01.12.2009; NRC Research Press; Canadian Science Publishing NRC Research Press
• Subjects: Agnatha. Pisces; Animal behavior; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Bycatch; Bycatch reduction devices; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fish; Fish behavior; Fisheries; Fishery conservation; Fishing; Fundamental and applied biological sciences. Psychology; Gadus morhua; Marine; Melanogrammus aeglefinus; Merlangius merlangus; Methods; Pollachius virens; Studies; Trawling; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Canada; ANE, North Sea; ANE, North Sea, Skagerrak; Melanogrammus aeglefinus; Benthic organism; Device; Selectivity; Orientation; Passage; Trawl; Capture; Pollachius virens; By-catches; Marine environment; Rejection; Vertebrata; Preference; Pisces; Models; Behavior; Merlangius merlangus; Localization; Comparative study; Gadus morhua
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/F09-145

This paper presents a quantitative approach to the study of fish behaviour in trawls with the aim of maintaining the catching efficiency of target species and reducing discards of unwanted bycatch. Differences in vertical distributions of species during passage through a trawl are used to sort the catch into separate compartments prior to size selection. It is demonstrated that behavioural differences may be utilized in separating species prior to size selection. Comparisons indicate that these patterns are consistent over replicate trials. Unlike cod (Gadus morhua), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), and whiting (Merlangius merlangus) do not change their vertical preference longitudinally in the trawl.