Abstract
AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 1:11-19 (2010) - DOI: https://doi.org/10.3354/aei00003 Spatiotemporal distribution of coastal and oceanic Atlantic cod Gadus morhua sub-groups after escape from a farm Ingebrigt Uglem1,*, Pål Arne Bjørn2, Hiromichi Mitamura3, Rune Nilsen2 1Norwegian Institute of Nature Research, Tungasletta 2, 7485 Trondheim, Norway 2Nofima Marin, Muninbakken 9-13, PO Box 6122, 9291 Tromsø, Norway 3Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan *Email: ingebrigt.uglem@nina.no ABSTRACT: Little is known about how escaped farmed Atlantic cod Gadus morhua L. affect the environment, but the potential for negative ecological consequences might be significant. In this study, the movements of adult farmed north-east Arctic cod (NEAC) and Norwegian coastal cod (NCC) were mapped after a simulated escape from an aquaculture farm to evaluate if post-escape movements and potential for recapture differs between these 2 genotypes. There was no major difference between NEAC and NCC equipped with acoustic transmitters with respect to spatiotemporal distribution or swimming depth during a 10 wk period after simulated escape incidents. The tagged cod immediately descended to average depths <20 m, and subsequently were most frequently observed along the shore. A substantial proportion of the farmed cod released at the cod farm left within the first week, while cod released at a nearby mussel farm were attracted to the cod farm. Beyond Week 2, the fish detected at the cod farm consisted of approximately similar proportions of fish released at either the mussel or cod farm. One third of the tagged cod was recaptured in local small-scale commercial and recreational fisheries during the first 3 wk after release. Thus, our results indicate that organised recapture fishery is a realistic option for reducing possible ecological and genetic impacts of escaped farmed cod. Such fishery must, however, be initiated as soon as possible after an escape incident and there is a need for development of a methodology for rapid detection and efficient recapture of escapees. KEY WORDS: Atlantic cod · Gadus morhua · Aquaculture · Fish escape · Recapture Full text in pdf format PreviousNextCite this article as: Uglem I, Bjørn PA, Mitamura H, Nilsen R (2010) Spatiotemporal distribution of coastal and oceanic Atlantic cod Gadus morhua sub-groups after escape from a farm. Aquacult Environ Interact 1:11-19. https://doi.org/10.3354/aei00003 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 1, No. 1. Online publication date: April 29, 2010 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2010 Inter-Research.
Highlights
Farming of Atlantic cod Gadus morhua L. is a growing industry and 13 500 t of cod was produced in Norway in 2008 (Lassen 2009)
There was no major difference between north-east Arctic cod (NEAC) and Norwegian coastal cod (NCC) equipped with acoustic transmitters with respect to spatiotemporal distribution or swimming depth during a 10 wk period after simulated escape incidents
The high escape risk of farmed cod is related to several factors; cod tend to bite holes in the net pen walls, they exhibit a swim pattern in the cages that involves a higher probability for finding holes in the net, and the technological and operational principles for cod farming in sea cages are principally developed for salmon and not for cod
Summary
Farming of Atlantic cod Gadus morhua L. is a growing industry and 13 500 t of cod was produced in Norway in 2008 (Lassen 2009). The proportion of cod escaping from farms is higher than for salmon farming, where, at the end of each year, on average 0.2% of the number of fish in the farms was reported to escape from 2004 to 2009 (data from the Norwegian Directorate of Fisheries). Genetic and other factors like hunger level, stocking density and environmental variation might affect the escape likelihood of cod. It has, for example, been shown that the 2 genotypes Norwegian coastal cod (NCC) and north-east Arctic cod (NEAC) exhibit a movement pattern within rearing tanks that might involve higher escape risk (Hansen et al 2008)
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