Thermoregulatory behaviour in cod: Is the thermal preference in free-ranging adult Atlantic cod affected by food abundance?

• Main Author: Björnsson, Björn
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2018
• Subjects: atlantic cod
• Online Access: http://hdl.handle.net/1807/94708; http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2018-0305

The study supports the hypothesis that well-fed cod seek higher temperatures to increase growth rate and poorly-fed cod select lower temperatures to save metabolic energy. Depth and temperature of free-ranging adult cod (44-79 cm) was studied with data storage tags as part of a ranching project in an Icelandic fjord. Forage fish was regularly provided at four feeding stations where cod formed distinct ‘herds’ (herd cod) that did not mingle much with the rest of the unconditioned cod in the fjord (wild cod). Several parameters: stomach fullness, liver index (fat reserves), condition factor and growth rate, indicated that food intake was much greater in herd cod than wild cod. In August, when the thermocline was well established, the herd cod remained in shallow (15-35 m) and warm water (8-10°C) whereas the wild cod stayed in deep (80-90 m) and cold water (3-4°C), but occasionally both groups explored depths and temperatures outside their preferred range. After vertical mixing in autumn when thermoregulation was not possible the depth difference between the two groups decreased significantly. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.