Abstract

This paper presents the field testing of a new technology to harvest marine copepods (Calanus sp.) by bubble-induced upwelling. Two large-scale bubble rafts, a 21 m(2) and a flexible 75 m(2) bubble raft with tow-parallel and tow-perpendicular sparger elements, respectively, were tested in the sea with high Calanus densities in the upper 25 m. Bubble-driven upwelling velocities (V(up)) measured with different air flows (Q) and source depths (z(0)), gave V(up) similar to Q(0.27) with stratified water, and were in agreement with other results for stratified conditions. Bubble trawls significantly enhanced Calanus concentrations in the upper water column: up to 1416%, with the best results for the transverse sparger raft, which also was tested with weak stratification. Bubble trawl performance also was affected by the stratification, with the highest enhancement for the lowest stratification. Catch species analysis showed reduced bycatch. Thus, this new harvesting technology showed a potential to develop an economically robust, environmentally benign, and sustainable fishery on a renewable resource at lower trophic levels in the food web, within the context of ecosystem-based management. (C) 2010 Elsevier B.V. All rights reserved.

Keywords

Harvesting zooplankton; Calanus; Air bubbles; Bubble plume; Engineered upwelling; Upwelling velocity

Published in

Fisheries Research
2011, Volume: 107, number: 1-3, pages: 147-158

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1016/j.fishres.2010.10.018

Permanent link to this page (URI)

https://res.slu.se/id/publ/32056