Cod

Gadus morhua Linnaeus 1758

These 49 fish had a mean total length of 54.5 cm (range 43– 75 cm), and were likely mature and of migratory size (Morris and Green 2002; Morris et al. 2014). Three fish with less than 50 positions were excluded from analysis. Some tagged fish were detected outside The Shinneys typically from June until September resulting in fewer VPS positional data during this time (Fig. 3). Of fifteen fish that moved out of The Shinneys in May and June as water temperatures increased above 0 ◦ C, nine returned before the water temperature became sub-zero (Fig. 3). Commercial and/or recreational fishers likely caught some or all of those that did not return. There was no evidence of mortality among tagged fish at the overwintering site during summer or winter based on continued detection and changes in positions of tags. Fish tracked in this study inhabited sub-zero temperatures continuously from December to June each year (Fig. 4A). Comparison between warm and cold (sub-zero) periods showed that the cumulative movement of tagged fish in The Shinneys was greater during the cold periods than the warm periods (ANOVA, F = 1421, DF = 4, p 0 ◦ C) than during the colder months (December–May) (ANOV

Field observations of the movements of locally adapted Atlantic cod (Gadus morhua) living in zero and sub-zero centigrade temperatures for half the year