Review of ESB’s eel trap and transport programmes

To mitigate for the impacts of their hydropower dams, the ESB runs a number of ‘trap and transport’ schemes for upstream migrating juvenile eels (elvers), and downstream migrating silver eels. However, in this article we ask is this a suitable or sustainable approach to eel management on Irish hydroelectrified rivers? and should more be done by the ESB to help eels on the rivers such as the Shannon and Erne?

We are now at the peak of the silver eel migration season; however the ESB aims to trap and transport only 30% of the eels migrating downstream on the River Shannon, with the other 70% destined to pass through the turbines with devastating consequences. They aim to transport 50% on the Erne; however the eels have to pass though two hydroelectric schemes on this river. We also question whether the physiological impacts – due to excessive handling – on the trapped and transported eels are too high.

During 2014 the ESB achieved unremarkable overall elver catches, in what was widely regarding as being the best year for elvers in 30 years. They did not commence elver trapping on the River Shannon until the second week of May, by which time the peak of the run had passed. Moreover, they allowed hundreds of thousands of elvers to die at their elver traps at Ballyshannon in what can only be described as negligence. We examine the issues below in relation to the juvenile eel trap and transport programmes, and the silver eel trap and transport programmes and ask if this approach is suitable or sustainable.

Juvenile eel trap and overland transport programmes

The elver run in 2014 was widely considered to be the best since the 1980’s. However, the elver catches on the River Shannon and Erne were unremarkable and the upturn in elvers was not registered at any of Ireland’s elver index trapping sites. There was a major elver kill this spring at the ESB elver traps in the Erne during which approximately 336,000 individuals – of a species currently listed by the IUCN as being ‘Critically Endangered’ – were killed.  This kill was exposed by us on our Facebook page, before being picked up by BBC news. The 112 Kg reported to have perished at the ESB traps at Ballyshannon represented 21% of the total reported annual catch this year on the Erne (532.9 Kg). From both a statistical and ecological perspective this was a significant quantity, and this elver kill would not have occurred if the traps had been operated appropriately. The current upturn in elver numbers may be just temporary so everything possible needed to be done to maximise the use of this run for restocking purposes. The ESB let over 20% of the elvers that were captured at Ballyshannon die, with many more likely to have died in the tailrace having been unable to find the entrance to the elver traps.

No one was on duty to service ESB elver traps over the bank holiday weekend
Cathaleen’s Fall hydroelectric station on the River Erne. The site of a massive elver kill this year.
The Ardnacrusha elver trap was not operating by the first week of May 2014 therefore missing the elver run.
The Ardnacrusha elver trap was not operating by the first week of May 2014 therefore missing the elver run. It is noted that over 85% of the elvers captured on the River Erne during 2014 were captured prior to the 7th May.

The current upturn in juvenile eel numbers commenced in 2012, and 2013 was also considered to be an exceptional year across Europe. This upturn was not registered at the ESB traps on the River Erne or Shannon however, and last year the ESB were still explaining away their low elver catches as being a symptom of the global downturn. They seemed to be unaware that there was a turnaround in numbers. We strongly suspected that the low ESB elver catches in 2012 and 2013 were related to an inadequate effort being made in relation to the trapping, and set out to investigate ESB’s activities on the River Shannon this year. The peak run of elvers on the River Shannon in 2014 took place in April (as it generally does each year). However by early May the ESB still had no operational elver traps on the River Shannon – either at Ardnacrusha hydroelectric station or Parteen Regulating Weir. It is noted that over 85% of the elvers captured on the River Erne during 2014 were captured prior to the 7th May, for example. We exposed the ESB’s failure to get traps up and running on the River Shannon, and it was not until the 8th May that the ESB commenced elver trapping operations on the River Shannon. The ESB therefore missed the main elver run on the River Shannon, as they were not operating traps in time. It must be noted also that even when the traps began operating, the ESB did not operate these traps efficiently. For example, they did not provide an adequate “attraction” water supply to the ramp. Moreover, there was also a significant volume of water leaking from the main spillway, and elvers would have been attracted to this instead and would have died or have been eaten by predators as they tried to climb up here.

In the UK the Environmental Agency see addressing non-fishery sources of mortality such as hydropower as being their highest priority, while seeking to maintain a sustainable and economically viable eel fishery

The 2014 juvenile eel catch on the River Shannon (from both Ardnacrusha and Parteen weir) came to only 354 Kg. This was only about 5% of the peak catches from these sites in the 1980’s, and only 10% of the peak catches from the 1990’s. All across Europe catches were reported to have been at 1980’s levels. The ESB catches are an anomaly, and can be easily explained by their poor efforts. The ESB clearly missed the opportunity to restock the Shannon and Erne (and of course the Lee and Liffey) this year.

We did not have an opportunity to visit the elver traps on the River Erne this year, but it is clear that these traps are also operated sub-optimally, with reference to the elver kill and the relatively low overall catches achieved this year by the ESB. We suspect that the Erne traps were not even being operated at the time of the elver kill, and that there were so many elvers in the tailrace that they climbed up into inactive traps and died in their hundreds of thousands. Other reports suggested that the ESB just left the traps operating over the bank holiday weekend with nobody on duty to service them, and no oxygen alarms installed. What is clear is that the ESB should have done much more than they did this year. This is clearly a missed opportunity as the current upturn in elver numbers may be just temporary.

We are concerned with the ESB’s current attitude to elver trapping, where they are claiming that they are in fact making suitable efforts. If this is the case they need to explain why their catches are so low, relative to other achievements across Europe over the past 3 years. We are very concerned that the way things are going the same inadequate effort will be made by ESB during 2015. Early indications from French rivers are suggesting that 2015 is going to be another bumper year for elver runs, although perhaps not quite as good as 2014. It is essential that ESB admit the mistakes that have been made, and put in place an efficient elver trapping programme for the 2015 season which is nearly upon us

Silver eel trap and transport programmes

We are also very critical of the ESB’s silver eel trap and transport programme on the River Shannon and Erne. We do not believe that this is a suitable mitigation measure for a critically endangered species. The majority of silver eels migrating downstream on the Shannon, for example, bypass the silver eel nets and have to descend through the turbines. The ESB’s nets are only operated intermittently and do not cover the entire river. The Eel Management Plan target is to trap and transport only 30% of the migrating eels, so the plan is for 70% of the eels to still go through the turbines. Silver eels can be large (especially the females) and are particularly vulnerable to turbine passage mortality and damage, and a large proportion of these eels are killed and damaged by the turbines and the pressure changes experienced. Meanwhile the 30% of eels that are caught in nets for the trap and transport programme are also undoubtedly impacted on. When they enter the nets they are held against the full flow of the river and then handled several times using nets and bins before being trucked and released. This handling almost certainly causes significant physiological damage to the eels but this has not been investigated. There have been reports of large numbers of eels dying in these nets – both on the Erne and Shannon – and it is clear that a significant proportion of the silver eels handled in this way will be stressed and injured, and may never spawn.

The latest European Commission report on the outcome of the eel management plans has specifically stated that more attention should be given to management measures related to non-fishing anthropogenic mortality factors, such as hydropower

Silver eel trap and transport
Ardnacrusha hydroelectric station on the Lower River Shannon, November 2014.
Cormorants
Cormorants feeding on turbine damaged silver eels at the junction between the boat canal and the tailrace, November 2014. Over 120 cormorants gather here each day to feed on turbine damaged eels
Killlaloe eel weir
Silver eel mitigation? Sorry it’s the weekend so we are not fishing. These nets at Killaloe cover only around half the width of the river and are only operated on selected nights.
Clonlara eel weir
This is the site of the former Clonlara eel weir on the ‘new’ Shannon (i.e. the headrace to Ardnacrusha hydroelectric station). When the ESB were catching silver eels commercially they set massive nets here each night during November to catch eels to sell for huge profits all over Europe. However, once they had to catch silver eels for their ‘trap and transport’ programme they decommissioned this fishery. Most of the silver eels passing downstream now pass through the turbines at Ardnacrusha.

On the River Shannon eel fishing was banned resulting in hardship for a large number of traditional eel fishermen and their communities, while not a single restriction was placed on hydroelectric generation activities. In our view the ESB’s trap and transport programme for silver eels was set up to be seen to be doing something and allow ESB’s hydroelectric generation operations to continue ‘business as usual’. We need to immediately look at curtailing hydroelectric generation during eel runs and releasing water through spillways instead to allow a greater proportion of the eels to avoid the turbines. There has to be some compromise in relation to hydroelectric generation going forward, both in relation to silver eel passage and elver trapping . On the River Shannon spilling water in the old river channel would also bring significant hydroecological benefits. The latest European Commission report on the outcome of the eel management plans has specifically stated that more attention should be given to management measures related to non-fishing anthropogenic mortality factors, such as hydropower. To date there has been no change whatsoever in hydropower operation protocols in Ireland to facilitate the sustainable management of the European eel.

There has to be some compromise in relation to hydroelectric generation going forward, both in relation to silver eel passage and elver trapping

In a restored Irish eel fishery we would maximise recruitment and replace hydroelectric turbine passage mortality with a sustainable fishery to the benefit of the eel, traditional fishermen and local communities alike. In the UK the Environmental Agency see addressing non-fishery sources of mortality such as hydropower as being their highest priority, while seeking to maintain a sustainable and economically viable eel fishery. In Ireland this seems to be the lowest priority – we put no restrictions on hydroelectric generation, closed all the traditional eel fisheries and only provided these ‘trap and transport’ schemes which are in no way a sustainable solution.

For further reading also see the following articles:-

And of course what about the salmon passage? There are virtually no salmon in the Rivers Shannon, Lee and Erne upstream of the hydroelectric schemes. So do not think that that things are being done right for salmon either. For more see here. We are also very much looking forward to seeing the documentary film ‘River Runner‘ which highlights the damage caused by the development of the River Lee hydroelectric schemes. It is becoming increasing clear that the there needs to be a major review of the management of Ireland’s hydroelectric rivers, and the programmes that the ESB runs to mitigate the impact of these schemes.