Thousands of River Lampreys trapped below Limerick weir

The photo gallery below shows River Lampreys Lampetra fluviatilis trying to pass Annacotty weir on River Mulkear, Co Limerick, during late-March 2017. This is in the Lower River Shannon SAC and these lampreys are on their spawning migration. The previous post raised this fish passage issue, but by the end of March 2017 thousands of lampreys were trapped below the weir trying to ascend. These photos were taken at night when the lampreys are most active.

These lampreys cannot pass this weir. Even early run River Lampreys cannot pass here as this weir is never flooded out and there are no side channels etc. where lampreys can pass. This is a total barrier for River Lamprey (and Brook Lamprey L. planeri) migration.

The following video also shows these lampreys at Annacotty weir. The video does not fully capture this however as it was filmed at night (on just a hand held iPhone). These lampreys cannot pass this artificial barrier – which serves no purpose and is just an ornamental weir which was installed in the 1990’s during an OPW flood scheme. The lampreys try repeatedly to pass this obstacle and get heavily predated on by Grey Herons Ardea cinerea. Approximately 20 Grey Herons were present here in late-March 2017 and they also fed on the lampreys at night, aided by street lighting.

The lampreys eventually give up and drop downstream to spawn below the weir. However, this causes them excessive stress and subjects them to very high levels of predation, and puts them at risk of disease. There are also concerns that commercial bait collectors target them at the weir. Lampreys are used as dead baits for Pike angling with packs of 3 lampreys selling for €5 or more. There is no protection of lampreys at this site.

There needs to be urgent action at this site to address this major problem. As the weir is ornamental an obvious option would be to remove it (outside the lamprey and salmonid spawning seasons). However, apartments have been built right up the bank immediately upstream and lowering the water levels could potentially destabilise construction foundations. If this was shown to be an issue, the weir could be lowered however and a low slope rock ramp (with no jumps at the top) could be installed. There is also potential to remove the sluice gates and install a side channel here to allow lampreys to ascend. What is is clear however is that something has to be done urgently.

Having the SAC lamprey population confined to below this weir makes it very vulnerable. There has also been an apparent decline in water quality in the lower reaches of the river, with excessive siltation evident during April 2017.

Heavy siltation in River Mulkear downstream of Annacotty weir, April 2017. This is the main lamprey spawning site due to fish passage issues at the weir. However lamprey populations are threatened by poor water quality in the lower reaches of the river.

Annacotty weir, April 2017. This weir serves no purpose but blocks lamprey migration in the Lower River Shannon SAC.

The lamprey “pass” installed here by Inland Fisheries Ireland under the €1.75 million Mulkear LIFE project cannot be used by River Lampreys which are a key conservation interest of the Lower River Shannon SAC. This lamprey “pass” also provides no significant benefit benefit for Sea Lampreys.

For further information please see the following links:

It is very disappointing that Inland Fisheries Ireland will not accept that there is a major fish passage at this site. They have claimed that 90% of lampreys use their lamprey “pass” but there is no evidence to support this claim. Indeed there is no scientific evidence that any lampreys use this pass, and it is certain that no River Lampreys use it. The photos and video above clearly demonstrate the problem here.

This weir also blocks the migration of the critically endangered European eel Anguilla anguilla and even Atlantic salmon Salmo salar salmon have difficulties – see this video from November 2016 https://youtu.be/-FHM1Yjxml0. I have offered to work on a voluntary basis with Inland Fisheries Ireland to design a passage solution for this site and prepare the Natura Impact Statement for any subsequent planning application. To date they have ignored this offer, but I am hoping that they will engage.

PS: I was very disappointed to hear reports on the 17th April 2017 from a reliable source that major illegal lamprey fishing had occurred on River Mulkear. It is suspected that fishermen will use baits at Lough Ree International Pike Festival where the prize money is €10,000. It is thought that this lamprey poaching occurs ever year, and I have certainly had my suspicions. It is of concern that despite that large run of River Lampreys this year there was little evidence of spawning activity downstream of Annacotty weir. 

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