Millions of glass eels in the Shannon estuary

Following on from the reports from the UK and other European countries that there are record numbers of glass eels arriving to European shores for the third year running, we can confirm what appears to be another massive run of glass eels has arrived into the Shannon estuary. We applied for a limited glass eel licence for the Shannon estuary from the Department of Communications, Energy and Natural Resources. We finally received this licence yesterday and did some experimental glass eel dip netting last night. It is is clear from the work we did last night and this morning that there is an abundance of glass eels present in the Shannon estuary again this year. We visited a number of sites in the Shannon estuary and it was quite apparent that there are probably millions of glass eels in the Shannon estuary at present. This is a remarkable turnaround in the fortunes of the European eel and this is the third consecutive year of a major increase in juvenile eel numbers.

Our licence allows us to retain samples of glass eels from the River Maigue estuary (a component of the Shannon estuary complex) and the upper Shannon estuary itself for scientific investigations. We were able to collect our authorised sample of glass eels from the Maigue estuary last night with just a couple of sweeps of a dip net – such is the abundance of glass eels that is present at the moment. We made visual observations at a number of other sites and it is clear that extraordinary numbers of glass eels are currently present in the Shannon estuary area.

The glass eels and elvers need to be caught and transported upstream around dams and other barriers to migration on rivers like the Shannon to safeguard the future of this species and restore its fisheries

We also made similar observations last year; however the run this year is considered to be even larger. The disappointing part about this however is that the vast majority of these glass eels will die over the next few weeks as a result of starvation, predation and disease and nothing is being done here in Ireland to make the most of these runs. We should be taking advantage of this current abundance and be using these eels for restocking; as is currently being done in the UK by the Sustainable Eel Group. The European eel is still listed as being a ‘Critically Endangered’ species and we need to be optimising the use of this current upturn. A small percentage of these glass eels will arrive to near the elver traps at the Ardnacrusha hydroelectric station in the next few weeks; however these traps are very inefficient and catch only a fraction of the elvers that arrive to this part of the river. Moreover it is likely that the majority of the glass eels currently in the Shannon estuary will never make it as far as the River Shannon itself due to high natural mortality rates and other factors.

The elver traps run by the ESB and Inland Fisheries Ireland in the Shannon Region are so badly designed and managed in our opinion that they have not even registered the current upturn in glass eel and elver runs, that has been ongoing for three years now. The (most recent) ‘Activity Report of the Standing Scientific Committee for eels, 2012‘ noted in relation to the elver catch on the River Shannon that “The catch in 2012 [on the River Shannon] was the second lowest on record“. This report then takes this as being conclusive evidence of the continuation of the downturn in eel numbers. What we would say is that the traps are in the wrong place, are not operated efficiently, and if you want to get elvers and glass eels to stock the River Shannon catchment you have to go further downstream and out into the estuary to get them. Inland Fisheries Ireland’s / ESB’s elver catch indices only work during a downturn in eel numbers. They are not measuring an index of eel abundance, they are just showing that they are not able to catch elvers and glass eels. For further comment on Inland Fisheries Ireland elver trapping indices see this post here.

Glass-eels-Shannon-estuary

Figure 1 Length percentage frequency distribution of 50 glass eels captured by dip netting in the Shannon estuary, 3 April 2014.

There is no reason why we can’t adopt sustainable eel management practices in Ireland, and indeed there is an urgent need that we do just that. The elvers and glass eels are there and available to restock our fisheries. It is time for Ireland to adopt the practices and standards of the Sustainable Eel Group. We need to be making the most of the current, perhaps only temporary, upturn in the numbers of juvenile eels arriving into our rivers. The glass eels and elvers need to be caught efficiently and transported upstream around dams and other barriers to migration on rivers like the Shannon to safeguard the future of this species and restore its fisheries.

It is time to commence sustainable eel management in Ireland, and the know how to do this is there through the Sustainable Eel Group

For further information on glass eels in the Shannon estuary see  Chapter 3 of the ‘Biology and Management of European Eel (Anguilla anguilla, L) in the Shannon Estuary, Ireland‘ by Dr. William O’Connor which gives an account of a pilot scale glass eel fishery that was set up in the Shannon estuary in the late 1990’s. This research was successful and showed that it was feasible to set up a glass eels fishery in the Shannon estuary – even at the time of the downturn in eel numbers. However, this research was ignored by IFI and ESB and excluded from all consideration in the Shannon IRBD Eel Management Plan. This research was excluded because of its success and it is apparently in the interests of both the ESB and IFI to have no good news stories in relation to eels and eel management in Ireland. However, it is becoming increasingly difficult for IFI and ESB to maintain this position and continue to ignore the ongoing dramatic turnaround in the fortunes of the European eel and the increasingly massive runs of glass eels that are arriving into the Shannon estuary in particular. It is time to commence sustainable eel management in Ireland, and the know how to do this is there through the Sustainable Eel Group.

Also see this post The return of the eel and also the post ‘glass eels in the Shannon estuary‘.

For further information on eels please do not hesitate to contact Dr. William O’Connor at +353 61 419477 or at  william.oconnor@ecofact.ie.