The future of fish-eating birds

Fersiwn Gymraeg ar gael yma.

The sight of birds eating fish, especially fish that people want to eat, has irked people for centuries. For example, ospreys’ prowess in fishing at stocked ‘stew ponds’ on country estates led to persecution that contributed to the species’ decline in the 17th and 18th centuries.

In recent times, the focus has been on cormorants and goosanders and in Wales one concern has been about their impact on Atlantic salmon and sewin (sea trout), which are declining in our rivers for several reasons.

Natural Resources Wales (NRW) has previously adopted a Plan of Action for salmon and sea trout, and has now agreed a policy on managing the impact of fish-eating birds. These were informed by an Advisory Group, of which RSPB Cymru was a member. This blog summarises our thoughts on that group’s report and the policies now adopted.

A tricky topic

The Fish-eating Birds Advisory Group looked at two species of birds: cormorant and goosander, and how these birds may affect fish populations in rivers and lakes. Other species, such as red-breasted merganser, were not part of the review and it was agreed that no fish-eating birds should be included on NRW’s General Licences. We have published another blog relating to General Licences, which was part of a wider recent review of NRW licensing.

It is a really complex topic. There is a good deal of uncertainty about the science, and it’s difficult to prove whether bird predation has a significant impact on fish populations. More science would help, but fully understanding the interactions between birds and fish in an aquatic environment is hard, since both are highly mobile. This makes decision-making a challenge.

State of Welsh rivers

There’s no doubt that Atlantic salmon and sewin/sea trout are in big trouble in Welsh rivers. Stocks in all the ‘principal salmon rivers’ in Wales are designated ‘At Risk’ or ‘Probably at Risk’ of failing to achieve their management targets until at least 2024. The story is complicated because salmon and sewin spend part of their lives at sea, and numbers returning to rivers are at a record low across the northern hemisphere, not just in Wales.

There are lots of reasons for fish declines that are nothing to do with birds. Climate change and lack of food in the marine environment are high on the list, but the state of Welsh rivers, especially from pollution from agriculture, sewage outflows and barriers to migration, are also big issues. The Advisory Group report stresses the need for all the factors affecting threatened fish to be tackled.

These pressures are serious, and the solutions needed are urgent. Birds should not pay the price for the historic poor management of Welsh rivers and the open seas.

Managing predation

We accept that there may be instances where predation by cormorants and goosanders may prevent the recovery of threatened fish populations, although this is difficult to prove. Any impact would be far less significant if rivers were in a good state, and that’s what we should all demand. There may be case to deter, or as a last resort, remove cormorants and goosanders from sections of Welsh river where fish are most vulnerable. The new policy requires priority to be given to non-lethal measures to manage predation. For NRW to issue a licence to kill fish-eating birds, it would need to be confident that it will really help to maintain fish populations while habitat restoration in underway. Since 2020, all Atlantic salmon caught in Wales must be returned to the river, as must sewin in most circumstances.

We worked hard to ensure that the report recommended that NRW decisions about future management of fish-eating birds are informed by good evidence. The Group did not, purposefully, recommend a ceiling for the number of fish-eating birds that could be killed in each catchment, but proposes that there should be one. RSPB Cymru welcomes that NRW intends to define favourable conservation status of fish and birds, with regular monitoring to understand the impacts of deterring or killing birds. We also welcome the commitment to annual publication of licensing information and to seeking funds for additional evidence necessary to inform decisions.

RSPB Cymru and the Welsh Ornithological Society could not support a recommendation that demands the licensed control of cormorants and goosanders during the salmon smolt migration in April and May. On the evidence available to date, it cannot be assumed that killing fish-eating birds during the breeding season will help to save salmon and sewin.

It’s vital that NRW resources gaps in knowledge, monitoring and deployment of non-lethal techniques, and – with Welsh Government - focuses on fixing the big problems facing our rivers, enabling both fish and birds to flourish in the future.

The NRW Board paper on the review is published here (pages 137-156) and a blog on some of the science commissioned from the British Trust for Ornithology is here.