Action needed to avoid risk of extinction for seven species of fish in Britain, according to University of Hull research

Seven species of fish are at risk of extinction in Britain’s waters, according to newly published research led by the University of Hull.

In what is the first formal assessment of extinction risk for fish in Britain, scientists reviewed data for the populations, ranges and habitat status of native freshwater fish including those that migrate between marine and fresh water across Britain.

The study, funded by Natural England, used the globally recognised, International Union for the Conservation of Nature (IUCN) Red List of Threatened Species™ Categories and Criteria to conduct a rigorous assessment.

Of the 42 native species of fish recorded in Britain’s freshwaters 34 were classified as freshwater resident or migratory and assessed in the regional Red List. One species, the burbot, has become extinct (lost in the late 1960s), and seven of the 34 species assessed were classified as threatened.

European eel and allis shad have been classified as ‘Critically Endangered’, Atlantic salmon, vendace and European whitefish are classified as ‘Endangered’, and Arctic charr and twaite shad are classified as ‘Vulnerable’.

Assessments were made for the whole of Britain and separately for England, Scotland and Wales by reviewing existing data from all available sources, including national fisheries and conservation monitoring programmes. This process was done together with Natural Resources Wales, NatureScot and numerous species specialists and organisations nationwide.

The study, which makes stark reading, is published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems. It concludes that multiple factors are at play in the decline of the threatened fish populations, including climate change, which is causing water temperatures to rise and flows to become more unpredictable. The study also points to other well-known threats to fish populations, particularly, the legacy of extensive habitat degradation in rivers and lakes. This includes pollution, loss of key habitats due to channel modifications and fragmentation, such as weirs creating barriers to fish migration. Overfishing and invasive species also threaten some populations, both in Britain and around the globe. This study has identified which of these threats are of greatest concern for the species of conservation importance in Britain.

Fresh water is considered the most threatened environment on Earth, and it was estimated that the World Wide Fund for Nature (WWF) Living Planet Index for populations of freshwater species declined by 83% between 1970 and 2012. Freshwater fishes account for more than a quarter of vertebrate species globally, and a significant proportion of these have declined in abundance or range in recent decades. At least 81 species have been declared extinct, including 16 since 2020 (IUCN Red List).

Dr Richard Noble, Research Associate at the University of Hull’s International Fisheries Institute, said: “The results did not come as a surprise, but they are cause for serious concern. The results have formalised the evidence surrounding the historic and ongoing declines in some of our freshwater fishes.

Dr Noble points out that a further 25 species were categorized as ‘Least Concern’, however, he warns these should not be overlooked as this does not necessarily mean there is no concern, as some are thought to be considerably less abundant than they were. For other species there is a paucity of data with which to estimate population sizes or measure rates of change. Steps need to be taken to ensure that species of conservation importance don’t join the growing list of threatened species.

This research highlights the threats to native freshwater and migratory fishes in our rivers and lakes and Dr Noble says it is an “important barometer” of environmental quality and biodiversity. He adds: “It is a red flag and formalising the assessment of the species in our waters is an important step in protecting freshwater environments.”

The IUCN Red List process works by assessing species distribution, population size and population change over a 10-year or three-generation time period (whichever is longer). Dr Noble and his colleagues believe that threatened fishes and species of conservation importance need to be monitored regularly and over long time periods to understand population change and that ‘significant investment’ needs to be made to ensure that both iconic and lesser-known fish species receive appropriate protection.

Dave Ottewell from Natural England stated: “We often think of individual well-known, iconic fish species when considering conservation actions, however, what this research highlights is the need to consider our whole native fish community and how the restoration of their supporting freshwater habitats is essential if we are to conserve them effectively, for the long-term.

That's why our Species Recovery Programme is improving strongholds for wildlife by investing in long-term species recovery, restoring more than 500,000 hectares of wildlife habitat to increase species abundance as set out in the Environmental Improvement Plan.".

Tristan Hatton-Ellis, from Natural Resources Wales, said: “This is the first ever Red List for freshwater fish, both in Britain and Wales. We already knew that our fish are struggling in the face of threats to our rivers and lakes such as climate change, water pollution and barriers to migration. This systematic and objective piece of work will focus and prioritise our conservation policy and actions and give further impetus to our strategic fish conservation projects around Wales.”

Colin Bean, NatureScot’s Fish and Fisheries Interactions Manager, said: “The completion of a Red List for British freshwater fish is long overdue, and this assessment will be of enormous help in identifying what conservation action we must take to halt the decline of Britain’s most vulnerable species. Atlantic salmon are - in Scotland as elsewhere - experiencing significant declines in the number of returning adult fish.

He added: “Landscape-scale action to protect and improve the condition of freshwater habitats is key to mitigating the climate emergency and ensuring the continued survival of less well known species such as Arctic charr, European whitefish and vendace. This is why we are working with partners to ensure that water bodies supporting these valuable parts of our freshwater biodiversity are protected.”