24-h cycles, the movement of fish was usually minimal with a maximum of 18 m·day−1 (mean
0.74 m·day−1, S.D. 2.09 m·day−1). On 21st December 2010, large relocation of almost all
individuals was detected, and six individuals displayed considerable activity during the 24-h
cycle with values of movement up to 259 m·day−1 (mean 35.21 m·day−1, S.D. 67.26). The
extent of average relocation during the whole period from2nd November 2010 to 1st February
2011 is shown in Figure 3. Finally, 17 of the fish occupied two very restricted areas (Figure 2B),
and only two individuals stayed out of these areas, in places with deficient DO levels. After
4th January, all the relocations and movements ceased again. The values and variability of
relocation, movement and HR among individuals are summarised in Table