In the Tay catchment we are fortunate compared to the other major Scottish salmon rivers in having a number of fish counters to assess the strength of salmon runs. The counters are nearly all located on spring salmon tributaries, mostly on hydro electric installations. The most important counters, at Pitlochry Dam, is situated on the lower reaches of one of the most productive spring salmon tributaries in the district. Furthermore, up to only a few years ago there was also a counter on the lower reaches of the River Ericht, the Tay's most productive spring salmon tributary but this was lost when the weir housing it collapsed. Thus until a few years ago probably more than half the Tay spring run was counted, providing valuable insights into the status of spring salmon.
(Data kindly supplied by SSE)
Annual “net” upstream counts at Pitlochry Dam, River Tummel, (that is down counts are subtracted from upcounts on a daily basis), 1951– 2012
Net monthly upstream counts, Pitlochry Dam, 1951 to 2012. Monthly data are not available between 1987 and 1991.
Pitlochry Dam spans the River Tummel, one of the major tributaries of the Tay. All salmon ascending must pass through a fish pass within which a fish counter is located. Also there are glass panels in the fish pass wall which allow salmon to be observed (see video clip). This facility is open to the public during the day.
The River Tummel is one of the main areas for producing spring salmon in the Tay district so this counter is particularly valuable for assessing spring salmon numbers, although there are some difficulties in interpreting the data which are explained in more detail by clicking here.
Though not as good as 2011, like 2011, 2012 saw one of the best counts since the late 1970s. Relatively good counts to the end of May and again to end June 2012, are suggestive of a good run of 2SW and 3SW fish, which was mirrored by catches during that period. The overall summer count was not unreasonable in 2012, but it is not known whether this was aided by continuing numbers of salmon rather than a good grilse run.
(Data kindly supplied y SSE)
Annual net upstream counts through Clunie Dam fish ladder, 1953 to 2012.
(note: counter malfunction occurred in 2005)
Net monthly upstream counts, Clunie Dam, River Tummel, 2003 to 2012. Monthly data are not available prior to 2003. Also, note malfunction in 2005.
The overall count at Clunie Dam on the River Tummel for 2012 was around the average for recent times, despite the count downstream at Pitlochry being relatively good. In keeping with the last few years, notably fewer fish ascended before the beginning of July than was the case a few years ago. As was the case in 2011, it is speculated that cool temperatures may again have prevented fish running in numbers in June, particularly given the Pitlochry counts show there were plenty of fish available to run at that time.
(Data kindly supplied by Scottish & Southern Energy plc)
Annual net upstream counts, Lochay Falls, 1960 to 2006
The Lochay Falls are a naturally insurmountable barrier to salmon on the lower reaches of the River Lochay near Killin. As compensation for the loss former spawning areas on the Lyon through damming, the North of Scotland Hydro Electric Board installed a borland fish lift to allow salmon access to the Lochay. In contrast to the other counters, the 2006 count was lower than for several years.
However, the count has never been very high and it is suspected that the Lochay has never been fully colonised by salmon, and this has been proven by electrofishing surveys. It has been suggested that inadequacies of the original design of the fish lift may be partly to blame, although there may be other factors. As part of the EU funded Conservation of Atlantic Salmon in Scotland project significant improvements to the Lochay lift are in the process of being undertaken in early 2007.
(Data kindly supplied by Scottish & Southern Energy plc)
Annual net upstream counts, Stronuich Dam, 1961 to 2006
Stronuich Dam is situated near the head of the River Lyon, about three miles downstream from the larger Lubreoch Dam which is the highest point to which salmon can ascend the Lyon. Salmon can ascend Stronuich Dam into this short length of river by a borland fish lift. The fish which reach this area are mainly a mixture of spring salmon and summer grilse. The majority of fish tend to pass through this counter in July and August though they may have entered much earlier. The long term average total counts have been pretty steady but when the effects of de-netting in the Firth of Tay in the 1990s is factored in it will mean that a real long term decline in abundance has occurred.
However, it was particularly encouraging that 2006 was one of the best counts there has ever been, but as the fish pass was completely refurbished in 2006 it is not clear yet whether this may have been due to improved efficiency of fish passage. The biggest counts in 2006 were in fact in July, which might have reflected the better spring run in ‘06, since the grilse run on the Lyon was late, as elsewhere. Spring salmon, of course, take some time to ascend this far.
Annual upstream counts, River Ericht, 1990 - 2006. Blue additions
represent possible additional counts in years of counter malfunction (1998, 2000 and 2001) but in 2003 is indicative of fish which were unable to ascend past the counter because of a drought late in the autumn but were rescued and transported upstream by TDSFB staff
Monthly upstream counts, Rove Ericht, 1993 - 2006. No data are available for 1996 nor before 1993. No spring counts are available for 1998 or 2000 when the counter malfunctioned.
The River Ericht counter is situated at Blairgowrie, only a few miles above the confluence with the River Isla. However it is situated upstream of a waterfall, Cargill’s Leap, which like Pitlochry Dam, acts as a temperature barrier. Therefore the timing of spring counts especially is no reflection on when the fish might actually have entered the Tay.
Since the counter was installed in 1990 the average level has remained pretty stable at around 8000 fish. However, the removal of the nets after 1996 will have helped the Ericht since most Ericht fish came in during the netting season. Had there been a level playing field the true abundance in the early 1990s would most likely have been greater than that seen more recently.
It was particularly encouraging that 2006 saw another excellent count on the Ericht, at 11,500, the third biggest count since the counter was installed in 1990. Counts to mid June and end June were at their highest recorded levels again reflecting the improved spring run. Again, like elsewhere, the main grilse run occurred late in the season reflecting the lateness of their arrival in the Tay and a period of low water. As in ‘05 grilse numbers were relatively good however.
Conclusions from Counters
The general conclusion from the fish counters in the Tay District is of a spawning stock which appears to have been pretty steady for some decades with no really apparent recent decrease. However, this has occurred over a period when there has been a major decrease in fishing as a result of the remove of net fisheries, the advent of catch and release and restrictions on angling methods (e.g. the shrimp and prawn ban). Therefore the counters hide the fact there has been a considerable decline in numbers of salmon entering the Firth of Tay over the last 20 or 30 years.
The Clunie Dam experience is especially interesting since this part of the Tummel has been recolonising despite formidable obstacles in the form of hydro dams which the fish have to pass. What it shows is that if numbers of juvenile salmon are low, the much better survival experienced by these few fish (because of low competition) can compensate for increased problems later in the life-cycle, and even though adult numbers in long established populations may have reduced, populations can still increase in poorly stocked areas. What this suggests is that the general decline which has occurred in salmon numbers is not necessarily a gradual spiral to extinction but a fall to a lower but nevertheless stable equilibrium. It has also been found in other rivers that removal of obstacles in recent times have resulted in rapid colonisation by salmon. In the case of the River Tyne, for example, it has been contended that this has been aided by hatchery operations (though the extent of this is the source of some debate) but on the Tweed there has been rapid recolonisation of big tributaries such as the Whiteadder after the removal of weirs even in the absence of stocking.