Salmon cycles

Salmon run characteristics are never stable and major changes in run timing and age of return from the sea have been demonstrated for many rivers including the Spey. At one time the Spey was considered to be a prime autumn river.  The “Interesting phenomena” section of the Spey Fishery Board Superintendents Monthly report for September 1954 contains a quote from Duncan Anderson “Head Fisherman” at Carron, who was retiring after 55 years on the river. When asked what was the most interesting thing that had occurred during his lifetime on the Spey he replied without hesitation “The change from an autumn run of fish to a spring run“. This he put down to the increase in the peaty water during the summer caused by grouse moor drainage and timber extraction during the wars.

Spey grilse

During the last few years the numbers of fish returning as grilse (after one year at sea) have declined significantly whilst the 2+ sea winter fish numbers have remained relatively stable. If we look at the graph above it can be seen that prior to 2009 the rod catch of grilse on the Spey didn’t dropped below 2000 from 1975. However in the four seasons since 2009 the grilse catch has been less than 2000 in three years out of four. Curiously the 2010 grilse catch was the 12th best in the last sixty years.

The period from 1952 to the 1980’s saw a gradual rise in the grilse catch. During the mid 50s the grilse catch was as low as 409; they must have been a rare capture at the time. Of course the river was predominantly a netting fishery then and exploitation of the summer runs, which included the grilse, may have been high and this would have influenced the rod catch.

After peaking in 1994 the numbers of grilse caught on the Spey have been declining. Tony Andrews of the Atlantic Salmon Trust summarised the current understanding of marine research at the River Spey Anglers Association AGM in 2012. His conclusions were that the Atlantic Ocean could be split in two with the eastern half, the Norwegian Sea etc, currently producing low productivity and consequently marine feeding, whilst the western half, the Greenland area, was particularly productive at present, all thought to be due to longterm changes in ocean currents. Grilse don’t travel as far as the multi sea winter fish and are generally thought to feed in the Eastern Atlantic, where the current low marine productivity is producing low survival and growth rates. This is a plausible explanation for the low number, and poor condition, of grilse seen in recent years.

It would be good to see increasing returns of multi sea winter fish but mortality of salmon at sea is thought to be quite consistent on a monthly basis so the longer they stay at sea the lower the number of returning fish will be for any given number of smolts. The number of MSW salmon landed in the Spey last year was almost spot on the average for the last ten years although from 1990 onwards there is a upward trend in the MSW catch but not enough to replace the distinct downward trend in the grilse catch.

I am not trying to “blind by statistics” (re: the good letter by Stephen Lodge in this months T&S) but it is always useful to be aware of the underlying factors influencing the catches on the river as a whole. So where does this leave the Spey? With some negative publicity over the last few years for sure but a ghillie on one of the fat lower Spey beats had a more positive take on the situation. He really liked working on that beat as they caught over 700 fish last year, the vast majority of which were good quality salmon; the sort of fish anglers come to the Spey for. I have some interesting figures for average weights of fish caught on the river in the last three years but I’m keeping that in reserve for the soon to be published Spring 2013 Spey Briefing. Personally I’m on the side of that ghillie, given the choice I’d rather catch one 15lb salmon than three 5lb grilse, but to be honest I’m usually glad to get a rise of any sort!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.