Why are there no salmon in the upper Shannon? : Part 2 – Management of Parteen fish pass
Unlike the Borland Fish Lift (or Lock) pass that was installed at Ardnacrusha at the end of the 1950’s, the fish pass at Parteen weir was included as part of the original Shannon Scheme. The pass is a traditional pool and transverse type pass, and the original design included side slopes where straw ropes could be laid to help young eels use the pass. For something built in the 1920’s this was a good design, and it still has potential to be optimised. However, there are major problems with the way it is currently managed, with brood stock collection and counting fish taking precedent over escapement of wild fish. This is unacceptable and is having a significant negative impact on the recovery of River Shannon salmon stocks.
One of the major problems on the Shannon at the moment is that what fish passage infrastructure we have is not being optimised. There is a reasonably good fish pass at Parteen Weir, but it is being operated as a fish trap rather than a fish pass. ‘Wild’ salmon trying to make their way to the upper Shannon need to be given absolute priority over brood stock collection, and this is not the case. In the 1990’s there was a change in management at the Parteen fish pass, where the trap was closed to prevent all salmon migrating upstream until brood stock collection began in September; to ensure that (1) all hatchery fish ascending the pass were captured and, (2) captured hatchery fish did not need to be held for long periods prior to stripping.
But this was a flawed approach. Upstream migration of salmon on the Old River Shannon was therefore totally blocked from early spring, until mid-autumn. When brood stock collection commenced in September, the trap was operated during work hours (8am to 4pm) Monday to Friday (excluding bank holidays) only. Any salmon migrating outside these hours hit a ‘dead end’ at the trap, which was closed outside these times. The salmon arriving here ‘out of hours’ may have included the last of the true residual stock of Shannon salmon.
You need to look at this from a salmon’s perspective. These salmon have come from the Atlantic and have ran through an immense estuary, and large river, and then are faced with a relatively small fish pass which they find after trying to jump the spillway several times (and formerly tried to enter the turbine draft tubes here). They then run the first few pools of the fish pass and get to a ‘dead end’. The salmon that try this get stressed, and then more often than not, drop back out of the fish pass. I would say that many do not try this way again, as it is a ‘dead end’. During working hours in the autumn and winter, salmon were netted out of the trap (more stress) with ‘wild’ fish thrown back into the fish pass above the trap to allow them to continue upstream. This approach was started in the early 1990’s and differed fundamentally from the management protocols which preceded this. Formerly, the trap was operated late in the year until enough brook stock was collected. Everything that entered the trap was used for brood stock, and when not trapping the pass was left open for fish to migrate freely upstream. Therefore ‘wild’ fish returning had a free run through the pass for most of the year. It is noteworthy that as well as making things difficult for fish that actually found the pass, it is likely that many fish arriving at Parteen dam never find the pass at all. The regular closure of the fish pass at Parteen, along with the proportion of fish that cannot find the pass, explains the mass spawning of salmon (both hatchery and ‘wild’) in the nearby Kilmastulla River that has been regularly observed. Although there are areas in this river for fish to spawn, there is not enough juvenile habitat to support their progeny so this is a loss to the system. While this was going on at Parteen, a similar approach was being taken at Ardnacusha. Here when the fish counter broke down (which was a regular event) the fish pass here was closed to (incredibly) ensure that no salmon ascended that were not counted. So salmon continued to decline drastically throughout the 1990’s, and it is likely that this flawed approach to management of the fish passes made a significant contribution to this decline.
There are now less salmon passing though Killaloe on the River Shannon than through the industrialised River Seine in Paris – some 250 km inland on one of Europe’s most polluted and modified rivers and above a major hydroelectric scheme. This is a startling example of the failure of fisheries management programmes on the River Shannon, and highlights the need for real change.
In the late 1990’s it was finally accepted that there was a problem with the approach of keeping the fish pass at Parteen closed, and it was accepted that salmon for which access was blocked during ‘out of hours’ time may never return and try to ascend the fish pass again. Since 1999, the screen on a 6” pipe that used to be the out flow from the raceway (where they store the brood fish) was removed, and a one way valve type screen was installed to allow fish to run up the fish pass, through a pipe and into the raceway. This was to be operated from September onwards, with the fish pass and pipe blocked prior to this. So a 20LBs salmon that has come from the Atlantic, a huge estuary and relatively large river, then enters a small fish pass, and is then presented with a 6” pipe. I suspect that many fish turn back at this stage, and it is totally unsatisfactory that ‘wild’ salmon in a ‘closed’ river below favourable conservation status are subjected to this treatment. Any fish that enter the race way will become stressed, and are handled several times before being trucked and released upstream. Salmon that enter the raceway continue to try to jump out of the inflow pipe at the top of the raceway. Hatchery fish also try to get out of the raceway, suffer injuries and often contract diseases. The ‘wild’ fish are held in the same raceway so can also acquire infections,
Some of the salmon that enter this raceway are from the lower Shannon, and Mulkear, and have overshot their destination. These fish are trucked upstream and then they try to drop down the river to find their natal spawning grounds. But is no way downstream for these fish, and they can be seen lined up at the top of the fish pass at Parteen and in front of Ardnacusha each year.
This is a startling example of the failure of fisheries management programmes on the River Shannon, and highlights the need for real change
Any ‘wild’ fish that are eventually allowed to continue their journey upstream have been compromised by this treatment. Nothing is being done at present by ESB to address this serious issue. Inland Fisheries Ireland doesn’t even seem to know about it.
So what could be done?
- The Parteen fish pass needs to be opened immediately and left open 24 hours a day, 365 days per year. Passage of ‘wild’ fish upstream has to be given absolute priority over fish census and brood stock collection. This can be done today, and would cost nothing.
The issue of catching fish for the hatchery will need to be worked out, but there should be no more interference with ‘wild’ fish. It may be possible to electronically tag every smolt released from Parteen hatchery. The trap at Parteen would then be upgraded to automatically trap electronically tagged fish, and allow ‘wild’ fish free passage upstream. This would remove the need for any further handling of ‘wild’ fish.
But in reality, serious consideration should be given to moving the hatchery upstream altogether. It hasn’t achieved much where it is, and there are these problems of separating fish. This of course would be a very expensive option, but why not?
- PS: ESB claim in their 2013 annual report that “The adult salmon trap [at Parteen weir is now] operated [from] the period 17th October to the 2nd of January with free passage allowed for all fish before and after this period”. But this is not true either as fish have to go through the pipe into the raceway. Salmon cannot use the pass by themselves to access the upper Shannon. The fact that they are trapping salmon now (for most of the year?) is likely to responsible for the increase in the salmon run from less than 200 fish in 2009 to over 1600 wild and hatchery fish in 2013. We would like to see this being independently verified, as they have also made claims about the operation of elvers traps which we have shown to be false. But the ESB will also need to explain why no salmon passed upstream at Ardnacrusha in 2010 (obviously the fish lift was not operated) and why in 2008 and 2009 that the run for the Shannon went so low (only a couple of hundred fish) – from graph in their 2013 annual report.