title: Size selection of Antarctic krill (Euphausia superba) in trawls.
abstract: Trawlers involved in the Antarctic krill (Euphausia superba) fishery use different trawl designs, and very little is known about the size selectivity of the various gears. Size selectivity quantifies a given trawl's ability to catch different sizes of a harvested entity, and this information is crucial for the management of a sustainable fishery. We established a morphological description of krill and used it in a mathematical model (FISHSELECT) to predict the selective potential of diamond meshes measuring 5-40 mm with mesh opening angles (oa) ranging from 10 to 90°. We expected the majority of krill to encounter the trawl netting in random orientations due to high towing speeds and the assumed swimming capabilities of krill. However, our results indicated that size selectivity of krill is a well-defined process in which individuals encounter meshes at an optimal orientation for escapement. The simulation-based results were supported by data from experimental trawl hauls and underwater video images of the mesh geometry during fishing. Herein we present predictions for the size selectivity of a range of netting configurations relevant to the krill fishery. The methods developed and results described are important tools for selecting optimal trawl designs for krill fishing.
authors.affiliation: DTU Aqua, Technical University of Denmark, Hirtshals, Denmark.
authors.forename: Ludvig A
authors.initials: LA
authors.lastname: Krag
authors.affiliation: SINTEF Fisheries and Aquaculture, Fishing Gear Technology, Hirtshals, Denmark.
authors.forename: Bent
authors.initials: B
authors.lastname: Herrmann
authors.affiliation: Institute of Marine Research, Bergen, Norway.
authors.forename: Svein A
authors.initials: SA
authors.lastname: Iversen
authors.affiliation: Institute of Marine Research, Bergen, Norway.
authors.forename: Arill
authors.initials: A
authors.lastname: Engås
authors.affiliation: Aker BioMarine Antarctic AS, Oslo, Norway.
authors.forename: Sigve
authors.initials: S
authors.lastname: Nordrum
authors.affiliation: Institute of Marine Research, Bergen, Norway.
authors.forename: Bjørn A
authors.initials: BA
authors.lastname: Krafft
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D049628:Body Size / Q000502:physiology*; D003247:Conservation of Natural Resources / Q000379:methods*; D033201:Euphausiacea / Q000254:growth & development*; D005398:Fisheries / Q000295:instrumentation* / Q000379:methods / Q000592:standards*; D008962:Models, Theoretical; D014741:Video Recording