With rising water temperatures this week, we are now well into the elver migration season. However, we visited four of Ireland’s national juvenile eel monitoring sites this week and found that three out of the four sites had no operational traps present. One trap was operational at one of the sites, but we considered that this trap was in the wrong place and was an insufficient effort for the site.
Ireland’s national elver monitoring index traps have not yet registered the current upturn in juvenile eel numbers. Why? because the traps are not being operated effectively, and as we can see from the photos below the traps are not even there at many of the sites. The observations we have made here illustrate how Ireland’s national elver monitoring “indices” are in fact not an index of eel recruitment at all. These index traps only “work” when there is a downturn in eel recruitment. Now that there has been a dramatic increase in elver runs these traps are only showing that Inland Fisheries Ireland (IFI) and the ESB are not competent to run a national eel recruitment monitoring programme.
Parteen Regulating Weir, Co Clare/Tipperary
We visited Parteen Regulating Weir on the Lower River Shannon on the 19th April 2014 and were very disappointed to see that the elver traps at this site were not operational. There are two traps at this site; the old one in salmon pass is broken. The other “new” trap just downstream of the salmon pass has no water supply, and had moss and other vegetation growing out of it. These are derelict traps.
It is also beyond disappointing that juvenile eels arriving at this site cannot pass upstream by themselves. They can only pass this dam by assisted migration, and this is a dead end for them here as the traps are derelict.
Even if these traps were being run they are not ideally located for this site. Elvers will be attracted to the spillway and there are traps only at one side of the river. According to the “Activity Report for the Standing Scientific Committee for Eel, 2012” (IFI, 2013) – the most recent one of these reports available – the catch recorded for Parteen Weir in 2012 was the second lowest on record. This was despite 2012 being an exceptional year for juvenile eels. We can see the reason for this in the photos below – these traps at Parteen Weir on the River Shannon are not being operated and therefore cannot catch anything.
River Maigue, Adare, Co Limerick
We visited Ireland’s national monitoring elver index site on the River Maigue at Adare on the 16th April 2014. Even though elvers are now running there is no sign of any traps present at this site. This is a quite incredible observation and it is of concern that this site does not have any evidence of elver trapping activity.
River Inagh at Ennistymon, Co Clare
This is another one of Ireland’s national monitoring elver index sites, on the River Inagh at Ennistymon, Co Clare. We visited this site on the 17th April 2014 and although there is one old derelict trap present at this site, there are no operational elver traps. Elvers are currently present at this site.
It is clear also that this old trap would never give an accurate indication of elver abundance at this site, even if it was working. This actual trap was originally designed and built by Dr. William O’Connor for use during his PhD studies in the 1990’s and it is incredible that there has been no investment in new traps as part of such an important national programme. This trap never worked well at this site even when it was operational, and the large catches made here during the 1990’s were mainly caught using dip nets. The current trap cannot catch anything as there is no water supply or collection bag.
River Feale, Finuge Weir, Co Kerry
We visited a third one of Ireland’s national elver monitoring index sites on the River Feale, Finuge Weir, Co Kerry, on the 18th April 2014. There is an operational elver trap present at this site. However, we think that this trap is in the wrong location and most of elvers here will go around the trap. There is a fall immediately below the trap and elvers cannot jump. They will go around this jump and then try to climb up the weir behind the trap. The entrance to this trap should be below this first drop. Alternatively strips of geotextile (i.e. tensarmat) should be extended downstream from the entrance to this trap to below the fall – this would encourage elvers to climb over the fall and into the trap entrance. This is a also a large river and a proper effort at this site would require at least two traps to be used – one at each side of the river. However, at least we have some form of an operational elver trap here – unlike the other national elver monitoring stations we visited this week – and a confirmed expenditure on Ireland’s national elver monitoring programme of least €200 in B&Q!
It is noted that we only visited four of Ireland’s national elver monitoring sites this week; however from just reading IFI (2013) it is clear that the other sites are also not being operated properly. Elver catches at the other site on the Shannon at Ardnacrusha are just too low for it to believed that genuine efforts are being made to trap elvers at this site. There have always been problems in relation to water supply and attraction to the trap here and there is no evidence that these issues have been overcome. Elvers arriving at Ardnacusha have to find a trickle of water flowing down the trap in a tailrace with up to 400 cumecs discharging from the nearby turbines. The best is not made of the trap here, and basic maintenance such as cleaning algae off the ramp and providing predator protection is not routinely undertaken. Elvers have to run a two stage trap here and there are often breaks in the continuity of the water supply which confuses elvers, and they often be seen going back down the ramp again as they cannot find the upper trap. The success of this trap is as influenced by its management as by the abundance of migrating eels, and with the current upturn in eels it is becoming increasingly obvious that poor management is the main influence.
These traps clearly cannot be indicating recruitment in the river, and are just an index of poor management
The elver catches at the traps at Cathaleen’s Fall on the Erne are also suspiciously low, and it is clear that we have a Parteen Weir situation in relation to the management of traps on the River Lee in particular. Likewise, traps on the Corrib and Liffey are just too low to be reflecting any kind of a credible effort.
The observations we made this week are further illustration of why Ireland’s national elver monitoring “indices” are in fact not an index of eel recruitment at all. These index traps only “work” when there is a downturn in eel recruitment. Now that there has been a dramatic increase in elver runs these traps are are only showing that Inland Fisheries Ireland and ESB are not competent to run a national eel recruitment monitoring programme. It is of serious concern that eel management policy in Ireland is based on this type of a programme. It is also noted that Ireland sends data to ICES which is complied into European juvenile eel recruitment statistics. These traps are not even being run so data from IFI’s programme is useless and is therefore undermining international indices of eel recruitment. These traps clearly cannot be indicating recruitment in these rivers, and are just an index of poor management.
- For further information on elver trapping on the Shannon, Maigue and Inagh see this document ‘Factors influencing the upstream riverine migration of juvenile eels on the River Shannon and selected tributaries of its estuary‘
- Also for previous comment on the elver traps on the River Inagh and Maigue see this post entitled ‘Are Inland Fisheries Ireland’s elver trapping indices accurate?‘
The poor catches speak for themselves; the low catches being as a result of poor trap design and location and sub-optimal management effort, rather than an absence of juvenile eels at these sites over the past few years. According to IFI (2013) “monitoring of recruitment is critical to evaluating the overall success of the eel regulation and is required by ICES for stock assessment“. It is very disappointing that such a, in their words, critical part of Ireland’s eel management plan is not being implemented in a satisfactory manner. In addition to providing management data, we are missing out on a real opportunity to use the current abundance of juvenile eels to stock our lakes and rivers therefore securing the future of the eel in Ireland and restoring its fisheries.