F. day: periods of migration. 



119 



It has long been a vexed question as to the manner in which 

 salmon enter estuaries and ascend rivers on their arrival from the sea, 

 and although doubtless local circumstances may occasion certain 

 differences, still the mode of migration would probably in all places 

 be somewhat similar were it unchecked. Mackenzie remarked of the 

 Scottish rivers that ' the salmon proceed with the flood tide, and rest 

 during the ebb in eddies and in easy water, hence great numbers are 

 always caught in the flood traps of the stake nets placed in their 

 course, while comparatively few are got in the ebb traps. If the ebb 

 sets in, and the water becomes shallow from the receding of the tide, 

 they drop down with the tide into deeper water, until the return of the 

 flood tide enables them to continue their course, and in this dropping 

 down some fall within the range and are caught in the ebb traps of 

 the engines in question ; but it is in the summer season, in dry 

 weather, that by far the greatest number are so caught.' At this 

 period the water in the rivers is so low that they swim about with the 

 tide, awaiting a flood. 



Admitting that the foregoing distinctly proves that in some 

 localities at least, large numbers of fish ascend with the flood tide, it 

 does not disprove that a great many also descend with the ebb, and 

 that in times or places when the very low condition of the water 

 could hardly be deemed a sufficient cause to obstruct ascent. In the 

 Severn, in the stretch of tidal water from Newnham to the railway 

 bridge, there are about seven sets of puts and putchers on the right 

 bank, all being fixed with their mouths up stream. On May 26th, 

 1885, 1 visited two of these sets of engines, and saw seven fish taken, 

 all with their heads fixed in the puts and putchers, and directed down 

 stream, and when captured they must have been descending the river 

 with the ebb tide. The stop-net fishermen carry on their occupation 

 during the ebb tide, more especially in the slack water, rendering it 

 evident that in this river these fish both ascend and descend in tidal 

 waters.* 



In the Severn these fish are observed to swim up with the tide, 

 which regulates their pace, as they rarely get in advance of it, and 

 follow a fixed track, probably the channel of the river; but as the tide 

 turns they leave the track by which they ascended, and are found in 

 the shallows. If once disturbed or frightened from their regular 



* Three views concerning these migrations were held at a meeting of the Dee 

 Conservators at Chester, in December 1884: — (1) That salmon run up with the 

 flood-tide ; (2) That they rest during the flood tide, and run up with the ebb ; 

 (3) That they allow themselves to be carried up with the stream of the flood tide, 

 with their heads towards the sea, and that when the tide begins to ebb they turn, 

 and continue their upward course against it. 

 April 1886. 



