LIFE R4Ever Kent trip to Ballinderry River Trust
18 July, 2024
FBA’s Assistant Kent Project Officer & Assistant Pearl Mussel Officer Jodie Warren reflects on the LIFE R4Ever Kent team’s recent trip to Northern Ireland.
In June, the LIFE R4Ever Kent team paid a visit to Northern Ireland’s Ballinderry River Trust (hereafter BRT). Here, we were to learn about their work in freshwater conservation, and specifically, their freshwater pearl mussel (FPM) captive breeding efforts. Networking is a key element to LIFE projects and allows us to share knowledge, techniques and experiences with other similar projects and organisations, to the benefit of all parties.
The BRT has a long history of FPM captive breeding, as well as releases and post-release monitoring. They are working hard with landowners in the catchment to improve water quality, as well as engaging with the government and local people to protect freshwater species and help improve understanding of river environments and the relationship that we share with them. Unfortunately, the Ballinderry river and its tributaries share many of the problems we face in the Kent – pollution, sedimentation, poaching of the riverbank, straightened channels, increased levels of nutrients, etc. This all accumulates to a lack of good quality habitat for FPM, which thrive in faster flowing, high oxygen and low nutrient rivers.
The Ballinderry river empties into Lough Neagh (Image 1), the largest lake in the United Kingdom, with a surface area of 151 square miles, and home to the dollaghan — a variety of brown trout native to the lake. The dollaghan trout is the host species for the FPM larvae (glochidia), which spend a small proportion of their life cycle attached to the gills of the fish, before they drop off into the sediment and remain on the riverbed for the rest of their long lives. Like most of us have seen on the news recently about England’s largest lake, Windermere, Lough Neagh has also been hitting headlines for its poor water quality and presence of blue-green algae. Despite its huge size, the lake faces many pressures starting miles upstream at the Ballinderry headwaters.
Image 1
On day 1 of the trip, we visited the BRT freshwater pearl mussel rearing facility, where they successfully raise not only FPM, but dollaghan trout and white-clawed crayfish (Image 3). After lengthy introductions, captivating conversations and presentations from both sides, we were led around the site to learn about their captive breeding processes and rearing systems. Given my role at the FBA as pearl mussel assistant, this part of the trip was extremely informative and allowed me to draw comparisons between the way we operate and the systems and processes that BRT employs to achieve the same goal.
BRT staff have a successful, hands-off approach to their captive breeding, which is very different to ours. They take a small number of adult trout from the Ballinderry and use them as broodstock. Female trout are ‘stripped’ of their eggs into a tray, which are then fertilised by the sperm of the wild-caught males. The fertilised eggs are reared ex-situ, while the adult fish are held at the site for a short period to recuperate, before being released back into the river. After a time, these very small, ‘fingerling’ dollaghan trout are put into a tank situated downstream of the adult mussels — when the mussels release their glochidia into the water column, the glochidia can attach themselves to the gills of the fish, known as ‘encystment’.
Once encysted, the fish are transferred into long rectangular tanks with a bed of gravel, simulating a river or stream, and over time the mussels drop off naturally and bury into the gravels (aka ‘excystment’, Image 4). After the excystment process the fish are removed and the gravels are left for five years (!) before being thoroughly checked for juveniles.
Image 4
BRT staff aim to keep things as natural as possible for their pearl mussels. The water they use for their systems is abstracted from the river on-site (within the Ballinderry catchment) and their rearing systems mirror the FPM natural environment.
After the initial 5 years of being buried in gravel, FPM juveniles are transferred into a large outdoor system which was built to simulate a river and encourage natural features and processes (Image 5). Water flows from one end of the tank and meanders around slats of wood creating different areas of flow. The tank is situated outside, and therefore experiences natural daylight rhythms as well as fluctuations in temperature and weather – preparing the juvenile mussels to real-life, river conditions. These mussels stay here until they are chosen by Frank as being large and robust enough to be released into the Ballinderry. Looking at Image 2, the mussels that are of releasable size are toward the upper end of the scale and have spent many years being looked after by Frank and his team at the juvenile rearing facility.
Image 5
After lunch we ventured out into the catchment. Frank and Peter showed us a site nearby in the Ballinderry where they had augmented a pocket of river with mussels reared at their facility (Image 6). They chose the sites based on the presence of mussels already there, and overall good habitat. The river was covered in ranunculus in flower (Images 7 and 9), another similarity with our river Kent, and in not-so-typical sunshine we casually made our way upstream, taking it all in.
We were shown sites where mussels thrived as well as sites where they didn’t do as well as they’d hoped - despite the presence of suitable habitat. We were told about how when flows get too high, mussels were scoured out from some areas of the riverbed, or, in some cases deposits of fine sediment covered areas where mussels were released. Despite the trials and tribulations of mussel releases, Frank’s work has been extremely effective and there are many more FPM existing in the Ballinderry now, thanks to the efforts of the BRT staff.
Images 6 & 7
For the second part of the visit, we were taken around the catchment to see completed works on farms. Staff at BRT focus much of their work on engaging with landowners to implement and/or improve infrastructures that reduce the amount of run-off entering the water from land. The BRT have access to money allocated from the government which mean that they themselves can disseminate funds to farmers to undertake practical work if it is for the purpose of improving water quality.
On several farms in the catchment, new drains, guttering and resurfacing have been built to direct water into storage areas, additionally, shelters have been erected to cover storage tanks and outdoor animal pens (Image 9), both of which prevent ‘dirty water’ from entering water courses following rainfall. In some cases, areas of river have been fenced off and solar pumps have been installed to provide animals access to river water, but by prohibiting access to the water course, they are reducing the impact of bank erosion, pollution and increased sedimentation.
Image 8
The team are also on hand to provide support and advice for landowners. It is clear that they have been able to build positive and strong relationships with the community, where farmers might start by improving their facilities for one reason but over time they become more invested in the positive effects of the improvements that they begin to enquire about what more they can do on their land for nature. Rachael, BRT’s Agriculture and Land Manager, highlighted how important it was to take the right approach with landowners. She explained to us how vital it is to use the correct language when trying to get across information, and how your attitude and persona can go a long way. These people, already looking after the land, are key to ensuring the long-term success of environmental restoration work led by BRT, improving water quality within the rivers and downstream at Lough Neagh.
Overall, the trip to Northern Ireland was extremely insightful and I have come away feeling inspired by their success. It was fantastic to get the opportunity to visit their FPM captive breeding centre and be able to compare the use of different systems and techniques with Frank and Peter. Surprisingly, perhaps my favourite element of the visit was listening to the team talk about how they work with landowners in the catchment. For me, they are creating a community between folks who work in agriculture with those in conservation, and it is this aspect is that I have come away with thinking about the most.
Image 9