During their upstream migration through the lower reaches of the Aberdeenshire Dee, Scotland, radio-tagged adult Atlantic salmon passed a Crump weir-based fish counter without substantial delay over a range of river flows and water temperatures. Tagged salmon were detected sequentially by automatic listening stations placed along the river and were detected at the counter site for a median time of 18 min, compared with a median time of 5 min before the weir was built. One fish out of 16 spent 6·7 h in the vicinity of the weir, but such migratory pauses also occurred before the weir existed. The results suggest that the number of salmon crossing the counter per unit time is a function of the number of fish present downstream and their tendency to migrate upstream, without being limited by their ability to surmount the weir. The apparent slight delay at the weir is probably insignificant in terms of the overall progress of riverine migration and in the context of using counter records to relate salmon movements to environmental Variables.
[1]
E. C. E. Potter,et al.
Movements of Atlantic salmon, Salmo salar L., in an estuary in south-west England
,
1988
.
[2]
T. F. Næsje,et al.
Within-River Spawning Migration of Atlantic Salmon (Salmo salar)
,
1988
.
[3]
A. S. Gee,et al.
The assessment of flow characteristics at certain weirs in relation to the upstream movement of migratory salmonids
,
1985
.
[4]
J. M. Hellawell,et al.
The upstream migratory behaviour of salmonids in the River Frome, Dorset
,
1974
.
[5]
J. W. Banks.
A Review of the Literature on the Upstream Migration of Adult Salmonids
,
1969
.
[6]
E S Crump,et al.
A NEW METHOD OF GAUGING STREAM FLOW WITH LITTLE AFFLUX BY MEANS OF A SUBMERGED WEIR OF TRIANGULAR PROFILE.
,
1952
.
[7]
P. Guéneau,et al.
Radio-pistage de saumons adultes (Salmo salar) en Loire
,
1986
.