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Global Swimways: conserving migratory fish populations

October 9, 2019
A salmon leaps Brooks Falls in Katmai National Park, Alaska. The Global Swimways project aims to map and protect migratory routes of such fish. Image: Christoph Strässler | Flickr Creative Commons

Migratory bird populations have long been supported through conservation schemes protecting their flight paths (which often span across continents and oceans). The mapping of such ‘flyways’ – used by millions of birds – allows for habitats at key stop-off points to be conserved and restored through protected area designations such as Ramsar wetland sites. Migratory bird flyways circle the world, and so protecting such key sites – variously used for feeding, breeding and over-wintering by different species – are crucial is crucial for the conservation of migratory bird populations on a global scale.

The term ‘flyway’ was coined by the American biologist Frederick Lincoln 1935 in an effort to describe migratory birds’ ‘ancestral routes’ of movement across seasons. The concept has been since been widely taken up in bird conservation – it’s a key idea in BirdLife International’s protected area planning, for example. Advances in tracking technologies are increasingly allowing scientists to understand not only to map and protect bird ‘flyways’, but also to observe how they are changing in response to pressures such as climate change, urbanisation and deforestation.

In comparison, the conservation of global migratory freshwater fish populations is lacking. Migratory fish species may travel thousands of miles between their spawning and feeding grounds, often moving between marine and freshwater habitats. The health of migratory fish populations therefore requires healthy, connected ecosystems which span both biogeographical and political boundaries. Many migratory fish species are important in sustaining human livelihoods, whilst others – such as the Atlantic salmon and Beluga sturgeon – are cultural icons which may act as ‘flagships’ for the conservation of wider ecosystems.

However, migratory fish species are in decline across the world as a result of multiple human pressures. Dam and weir construction can block migratory routes up river systems, water abstraction and pollution can destroy spawning grounds, whilst changing water temperatures as a result of climate change can alter food availability for migratory species. At present, though, too little is known about the status of many global migratory fish species and their conservation needs.

Swimways of the World map produced by the World Fish Migration Foundation (explore in more detail here).

In response, a new ‘Global Swimways’ project has been launched this month, aiming to apply the insights of the ‘flyway’ concept to global migratory fish conservation. As part of this project, scientists will create the first global map of fish migration routes, identifying migration hotspots or ‘swimways’ and develop a new tool that highlights presence of migration routes near existing or planned infrastructure.

“Since the 1930s, people have developed and utilised the concept of flyways for the conservation of birds. They realised that in a world of changing habitats and building threats, you need global cooperation. It has led to successful agreements such as the Ramsar convention and international policies for conservation of ecological hotspots,” says Dr. William Darwall, project lead of the Global Swimways project, and Head of the Freshwater Biodiversity Unit of IUCNs Global Species Programme.

“We believe we can similarly use this developing concept of swimways for migratory fish and aim, through this project, to gain the momentum for taking this forwards as a tool to inform global policy and raise awareness leading to action. As soon as we have increased our knowledge and understanding of individual species migration routes, we will set criteria to identify swimways as globally important migration corridors.”

The project is a partnership between IUCN, the UN Environment Programme World Conservation Monitoring Centre, the University of Cambridge and the World Fish Migration Foundation. It is intended that the ‘swimways’ concept will help strengthen arguments for the conservation of migratory fish with policy makers. The project aims to raise awareness of the economic and cultural value of migratory fish, alongside their vulnerabilities to development along migration routes.

It is intended that the project will help inform the cost-benefit analyses made in planning large-scale dams and hydropower constructions (which are booming across the world). In other words, the Global Swimways project intends to highlight the value of global migratory fish and their remarkable life-cycles in an effort to strengthen their conservation and restoration.


Find out more about the ‘Global Swimways’ project here.

Explore the ‘Swimways of the World’ map produced for World Fish Migration Day.

Bending the curve of freshwater biodiversity decline

September 27, 2019

What are the most significant and pressing freshwater biodiversity research questions that, if answered, would improve our ability to understand the state of freshwater biodiversity and improve its management and restoration, now and in the future?

This is the question asked by researchers affiliated with the Alliance for Freshwater Life as part of a new ‘horizon scanning’ research project seeking to identify the big questions in freshwater science, policy and conservation.

Horizon scanning research in conservation

Such horizon scanning projects have increased in popularity in recent years in environmental conservation, often creating valuable resources for students, academics, policy makers and environmental managers. For the last ten years, Prof. William Sutherland from the Conservation Science Group at the University of Cambridge, UK has been leading horizon scanning research for global conservation issues in collaboration with colleagues from across the world. This work is carried out using literature reviews and surveys with experts and stakeholders.

Sutherland and colleagues highlight that horizon scanning research is particularly good at ‘closing the gap’ between academia and policy-making by identifying key research questions of common interest. Their 2019 review of emerging issues for conservation includes a number of freshwater topics, including meltwater from Antarctic ice sheets and the environmental impacts of a planned 6188 km canal in Northern China.

Emerging issues in freshwater conservation

A classic review paper of emerging issues for freshwater conservation was published by Prof. David Dudgeon and colleagues in 2007. One of their opening statements – “Fresh water makes up only 0.01% of the World’s water and approximately 0.8 % of the Earth’s surface, yet this tiny fraction of global water supports at least 100 000 species out of approximately 1.8 million ‐ almost 6% of all described species” – is routinely cited across academia, policy and management circles.

Similarly, their identification of five key issues – over-exploitation; water pollution; flow modification; destruction or degradation of habitat; and invasion by exotic species (with climate change added in a 2010 follow up paper) – remain central to freshwater conservation debates and practice.

‘Bending the curve’ of global freshwater biodiversity decline

Whilst there are a growing number of horizon scanning research projects focusing on freshwaters (for example), the new call by Alliance for Freshwater Life researchers aims to provide a comprehensive of the key research topics, both now and in the future. In this way, they hope to generate and synthesise global knowledge and expertise to help ‘bend the curve’ of global freshwater biodiversity declines – in other words, to address the downward trajectory of many freshwater species and ecosystems across the world.

The ‘bend the curve’ phrase was used last year in a paper by Prof Georgina Mace and colleagues, who argued that the development of the post-2020 strategic plan for the Convention on Biological Diversity provides a vital window of opportunity to set out an ambitious plan of action to restore global biodiversity.

Meagan Harper, a graduate student at Carleton University, Canada who is co-ordinating Alliance for Freshwater Life survey says: “Freshwater biodiversity has been experiencing population declines at as much as twice that experienced in marine and terrestrial ecosystems. While we have known about the problems facing freshwater biodiversity for a while, coordination among groups trying to improve freshwater biodiversity has been slow.

“We think this call for questions, and the research agenda that will be produced, will help increase this coordination among researchers and policy makers, and will help increase our understanding of where gaps in our current knowledge are impeding progress in freshwater biodiversity conservation.”

“We are hoping to accomplish several things with this project,” Harper continues. “First, to produce a research agenda or guide that would provide ideas for early career researchers or fundamentally-oriented researchers on how to engage in applied freshwater biodiversity science. Second, to signal to funders and managers/policy makers where additional research is needed. And third, to identify common projects for groups like Alliance for Freshwater Life, Shoal, and InFish, among others, as well as areas where we as a community can invest our efforts.”

“Ultimately, our purpose in creating this list is to help in the effort to stop, or even reverse, the current trajectory of freshwater biodiversity loss, to ‘bend the curve’ for freshwater biodiversity,” Harper concludes.

You can take part in their Alliance for Freshwater Life horizon scanning survey here.

Vivid and lively aquatic worlds: the art of Jacek Matysiak

September 10, 2019
Salmon. Image: © Jacek Matysiak

We recently came across the work of illustrator and designer Jacek Matysiak, and were so impressed that we knew we wanted to share it with you. Jacek is based in Dublin, Ireland, and his work provides a unique window onto the natural world. We caught with him recently to find out more.


Freshwater Blog: Your illustration and design work is focused on images of the natural world — what inspired you to take this direction? And how did you get started?

Jacek Matysiak: I grew up in a town that was surrounded by beautiful lakes, rivers and conifer forests; the proximity to nature and ease of access have eventually given me some ideas to capture the mood of wilderness in a more creative and artistic way. I was initially more drawn to photography but eventually discovered the medium of illustration and started to enjoy it much more, as it gave me broader opportunities.

Arowana. Image: © Jacek Matysiak

FB: There are some iconic freshwater animals in your portfolio — arowana, pike and osprey to name three. What draws you to aquatic environments, and what are some of the challenges and opportunities of depicting them?

JM: I have spent most of my life near freshwater environments, and heading to a fishing weekend trip, kayaking on a lake or spending a day out in a forest is a common activity throughout most of the year. Naturally you would be observing creatures like freshwater fish, majestic birds of prey and mammals that came up close to the water.

The biggest challenge is to avoid creating very generic images in your art. I see a lot of good work that is depicted in a very realistic and nearly scientific way. Even though I want to achieve a certain degree of accuracy, I also strive to give my characters more cartoon-like features and stylize them in a particular way.

Osprey hunting. Image: © Jacek Matysiak

FB: What is your process? Do you undertake fieldwork, or work largely in the studio? What are your tools and materials?

JM: It is a combination of both really. Whenever I can afford it, I do spend a lot of time in the wild and try to capture the look and feel of the environment, observing the landscape, taking various photographs and doing quick sketches but sometimes I inevitably have to rely on other resources.

I work at home or sometimes in a cafe. For sketching I use mainly pencils, color pencils and lately posca pens. For finished work I complete my artwork largely in Illustrator and often do some additional coloring and add textures in Photoshop.

Page spread from ‘Obscure Cycle’, a book about the eel life cycle. Image: © Jacek Matysiak

FB: Tell us about Obscure Cycle — your book about the eel life cycle. What drew you to this fascinating creature, and how did you go about depicting it?

JM: As you say, an eel is such a phenomenal creature that it simply creates a great story on its own. Last year I was very eager to do a small picture book about a fish, and initially had a pike in mind, but eventually went for an eel, as there is so much more to write about it.

The book is constructed in a form of a loop, with the beginning and end in the Sargasso Sea, depicting eel’s treacherous journey. I wanted people to find out more about eels and stop dismissing them as ugly and creepy cadaver eaters. It is also important that people understand how endangered eels are and how serious the problem of glass eel trafficking is.

Frog. Image: © Jacek Matysiak

You write on your website that you put a ‘strong emphasis on vivid and lively colors, highlighting the beauty and diversity of our planet.’ What role can the creative arts play in highlighting (and even helping address) environmental problems?

Art is a brilliant form of expression and I think it can help bridge the gap between the scientific and common perception of natural environment. Through the use of appealing and powerful images we can reach a much broader audience that we normally would and engage people of different ages in understanding the key environmental issues.


Jacek Matysiak website.

Climate change increases flooding in some European regions and decreases it in others

August 31, 2019
The flooded River Test in Wherwell, Hampshire. The UK is one of the European regions with significant increases in flooding since 1960. Image: Neil Howard | Flickr Creative Commons

Human-driven climate change is causing significant changes to the pattern and extent of river floods in Europe, according to a major new study.

A large, multi-national team of researchers analysed river flow data from 3,738 of catchments taken over a 50 year period between 1960 and 2010. Writing in the journal Nature, the team – led by Prof Günter Blöschl and Dr Julia Hall – outline clear regional patterns in the data.

Regional flood discharge trends in Europe range from an increase of around 11% per decade to a decrease of 23%. The study authors identify three European regions where flooding has either increased or decreased over the study period.

Regional patterns of flooding change

Increasing autumn and winter rainfall – and the resulting wetter soils – over the last 50 years in northwestern Europe has caused an increase in flooding. Around 69% of river flow stations in this region show an increasing flood trend, with an average local increase of flow of 2.3% per decade.

In medium and large catchments in southern Europe, floods are decreasing because of lower rainfall and increasing evaporation from the soil. However, in some Mediterranean areas, small rivers can experience more floods due to frequent thunderstorms and alterations to their catchments, such as deforestation. In this region, around 74% of stations show a decreasing flood trend, with a regional average decrease in flow of 5% per decade.

In Eastern Europe, flood levels are decreasing due to less extensive spring snow cover, a shift to rainfall (rather than snow), and earlier snowmelt as a result of higher air temperatures. However, extreme precipitation in the summer has increased in the summer in this region. Here, around 78% of stations show a decreasing flood trend, with an average decrease in flow of 6% per decade.

Joint lead author of the study, Professor Günter Blöschl of the Vienna University of Technology, says: “We already knew that climate change is shifting the timing of floods in a year, but the key question had been, ‘Does climate change also control the magnitude of flood events?’. Our study did in fact find there are consistent patterns of flood change across Europe and these are in line with predicted climate change impacts, such as a contrast between increasing severity of flooding in the north and decreases in the south.”

Jamie Hannaford of the UK‘s Centre for Ecology & Hydrology, one of the scientists who was involved in the research, says: “This timely study adds to a growing body of evidence that shows that flood magnitude has increased in the UK over the last five decades, particularly in parts of northern and western Britain.

“We show this is part of a continent-wide pattern of changes in flooding which is in line with what we may expect in a warming world. This highlights the importance of long-term hydrological monitoring and the benefits of data sharing and collaboration at a European scale in order to better understand the mechanisms behind observed changes in flooding.”

Flood risk management

The research team’s results have implications for flood risk management in European river catchments. River managers often use the ‘return period’ concept to model how often floods of a certain size (and impact) will recur in their catchments.

The study authors highlight that in regions with increasing flood discharges, the 100-year flood discharge of 50 years ago now has a return period shorter than 100 years. In other words, large floods now be expected more regularly. As a result, the flood defences built to mitigate the risk of extreme flooding may no longer be sufficient.

In contrast, in regions where flooding is decreasing (such as Eastern Europe), the return period of large floods is increasing. The authors estimate that large floods which happened only once every 100 years, will now have a 125 to 250 year return period.

The study authors suggest that changing patterns of flood risk driven by climate change across Europe must be taken seriously by policy makers in order to mitigate the potential devastating impact on affected communities.

Dr Neil Macdonald of the University of Liverpool, a co-author of the study, says: “Flood management must adapt to the realities of our changing climate and associated flood risk over the coming decades.”

Dr Thomas Kjeldsen of the University of Bath, another co-author, adds: “Incorporating the evidence of increasing flood risk into engineering design and general flood management would ensure we are better prepared for future changes – a point also raised in the UK Government’s National Flood Resilience Review.”


Günter Blöschl et al. 2019. Changing climate both increases and decreases European river floods. Nature. DOI: 10.1038/s41586-019-1495-6

Check, clean, dry: how can canoers help control the spread of invasive species?

August 16, 2019
power wash kayak
Power washing canoes and kayaks after use can help remove fragments of invasive plant species and control their spread between water bodies. Image: Paul Jepson

A guest blog by Dr. Paul Jepson, Nature Recovery Lead at Ecosulis Ltd.


On a hot Saturday in June I rolled up at the UK’s National Water Sport Centre. The place was abuzz with cars, kayaks, club flags and paddle-carrying athletes chatting bucket starts, heats, duck tape and Nelos. Everyone was readying to race on a highly engineered stretch of freshwater. It looked and felt a world apart from my world of conservation science and policy. Yet walking along with my daughter to get her kayak weighed, I spied a Wildlife Trusts flag and two fellow conservationists raising awareness of biosecurity and invasive species.

Gemma Rose and Helen Carter-Emsell work for North Wales Wildlife Trust, and had made the 120 mile journey to Nottingham to promote good conservation practices among kayakers. Gemma explained that the River Dee, which rises in Snowdonia and flows into the sea near Chester on the Welsh / English border, is rich in native wildlife but also hugely popular with canoeists.

“Invasive species represent a key threat to the Dee river system, and we are worried that people who use rivers for recreational activities such as canoeing have the potential to bring in invasive species and also transport ours to other river systems. The Welsh Government share these concerns and fund the Trust’s ‘Our River Wellbeing Project’ within the Dee catchment,” Gemma said.

The Trust has teamed up with British Canoeing and the GB Non-Native Species Secretariat to raise awareness among canoeists of invasive species and the damage they can do to aquatic systems.

“Fragments of crassula or balsam seeds can get inside the boat and lodge under seats and foot pumps, on paddles, spray decks and clothes,” explained Helen. “We are asking kayakers to check clean and dry their boat and kit after races, so they don’t transfer invasive species from river to river. We want to protect our native species.”

check, clean, dry
The ‘check, clean, dry’ message.

The ‘check, clean and dry’ message emblazoned on the awareness materials was clear and simple, and Gemma and Helen’s dedication to spray washing kayaks provide a practical demonstration of what was needed. However, adopting this practice didn’t seem that straightforward to the kayakers whose ways I had come to know a little in my role as a ‘supportive Dad’.

I wandered back through the throng of competitors and supporters to the Falcon club’s gazebo overlooking the race water. I slumped into a camping chair next to Keith Long, another Dad and a keystone volunteer for the club, and together we worked through what it would take to reduce the risk of canoeists spreading invasive species from river to river.

The first thing to mention is that canoeing is both a sport and a leisure pastime. Many people own their own leisure canoes, but the focus of our discussion was the club and sporting aspect of the hobby. This is organised into three disciplines: sprint, slalom and marathon. The first two are Olympic disciplines and are centred around purpose-built facilities.

Marathon is the popular every-day club sport with regular races organised and hosted by different clubs. Transporting kayaks from river-to-canal-to-river system is part of marathon racing and this is where the greatest risk of transferring invasive species lies.

Parked behind us was the club trailer. Keith told how he can transport 22 kayaks on the trailer and another 4 on his van roof if need be. “At marathon races we are parked up on grass fields. There are a hundred or more boats and no wash down facilities,” Keith pointed out. “People get home from races tired and cold, so they just shove their kayak in the boat shed and take it out for the next training session.”

Working though the practicalities of ‘check, clean and dry’ we agreed that realistically this could only happen back at a club, but this would require a facility to ensure that any washed-off invasive species do not enter the local watercourse. It wasn’t hard to come up with a design – a rectangular trough filled with different grades of gravel, wiring for a couple of spray washers, and fixed boat supports.

Although the costs of installing wash-down facilities wouldn’t be massive it would be beyond the means of most clubs. Controlling invasive species is clearly a public good, and this should be something government agencies should support.

wildlife trust at national water sport centre
Conservationists from the Wildlife Trusts at the National Water Sport Centre. Image: Paul Jepson

The next challenge would be to get kayakers to adopt the practice of washing down boats and equipment after they have travelled between river systems. We discussed the possibility of juniors doing this as way to build awareness ‘youth-up’ and at the same time install values of volunteering and ‘giving back’ that are so important in club and community life. “Give them the opportunity to use a spray washer!” exclaimed Keith. “They’d love it – under proper supervision of course!”

Responding to an early version of this blog, a colleague from the Environment Agency pointed out that there are battery-powered spray-washers. This opens the possibility of washing down kayaks on riverbanks after racing, which is the ideal from a biosecurity perspective. One option would be for race committees to introduce a biosecurity check after races. Kayakers are required to go through a boat check for buoyancy and numbers ahead of racing so this would represent an extension of current practice. However, host clubs need to mobilise nine to twelve volunteers in shifts to run the pre-race checks. Adding a more time consuming and messy second boat check would likely beyond the volunteer capacity of most clubs.

Equally problematic is the last component of the ‘check, clean, dry’ message. Gemma was keen to stress that leaving boats to dry in UV light for 48 hours was the surest way to kill off hitchhiking non-native species. Unfortunately, most kayakers lack the space and security to leave boats outside and UV light can weaken their construction. I asked Lucy Bagnall from Kirton Kayaks for an expert opinion on this last point. She explained that, “racing kayaks are increasingly constructed from epoxy resins that bind well with carbon fibres but can become unstable when exposed to UV-light. This is why manufacture’s warranties and care guidelines state that boats should not be left in the sun.”

Richard Atkinson, Waterways and Environment Policy Officer with British Canoeing commented, “Invasive species are top of my list of policy priorities. We have just begun our journey of engaging canoers in practice to reduce this. We are still working through practicalities and ways to engage the clubs. Our partnership with the Wildlife Trusts is a great step. As well as kayakers to adopt biosecurity practices we are also mobilising canoers to help in the removal of invasive species such as pennywort and clear up plastic debris.”

Driving home I reflected on the notion of policy engagement and how this needs to be a journey of co-learning where policy professionals move beyond simple awareness messages to actively research and embrace the culture and practices of those whose behaviours they seek to influence. There are several points of alignment between kayaking life and good biosecurity practice. But there are also very real points of divergence. As my daughter noted, “We all know that its best to wash gunk and salt of our boats after races. But when you get off the water exhausted and with numb hands it’s the last thing you want to do!”

The control of invasive species is a public good and this places a responsibility on competent government agencies to provide the resources and finance to work with canoe clubs to co-design a practical approach to aquatic biosecurity.

Toxic legacy of historical pollution hinders ecological recovery on urban rivers

August 3, 2019
The River Taff in South Wales. Whilst salmon and otters are returning to this river – once highly polluted by industrial discharge – ‘legacy pollutants’ may be hampering its ecological recovery. Image: Judy Davies | Flickr Creative Commons

Toxic chemicals released in past decades could be impeding the ecological restoration and recovery of Britain’s urban rivers, according to a new study. ‘Legacy pollutants’ such as PCBs (Polychlorinated Biphenyls) and flame-retardant chemicals (PBDEs) from historical industrial discharge persist in river catchments, potentially disrupting aquatic food webs.

Fred Windsor, lead author of the new study, explained: “Despite major success in controlling sewage pollution in South Wales’ rivers over the last three decades, something appears to be holding back biological recovery.” Windsor, a doctoral student at Cardiff University, continued: “Our investigations show that persistent contaminants might be responsible as they still occur widely in invertebrates, particularly in urban river environments.”

Windsor and colleagues sampled eighteen sites across the Taff, Usk and Wye catchments in South Wales. They found that sites in urban locations had damaged food chains and fewer invertebrate species compared to more rural rivers.

Water quality and ecological health has been dramatically improved on these rivers since the 1970s, when over 70% of South Wales rivers were classified as ‘grossly polluted’ due to a combination of poor sewage treatment, colliery waste and industrial discharge.

However, writing in the journal Water Research, Windsor and colleagues suggest that the toxic pollutants from this era still persist in urban rivers, hampering efforts to continue their ecological recovery.

Co-author Professor Charles Tyler, from the University of Exeter’s School of Biosciences, explained: “These apparent effects of what we call ‘legacy’ pollutants – PCBs, flame retardants, organochlorine pesticides and other complex organic chemicals that have now been largely discontinued from production and use – are yet another reminder that we continue to live with problems caused by toxic chemicals from past decades. These chemicals still occur widely in rivers, lakes and seas in Britain and beyond, and still affect a wide range of animals.”

The research team found that river food webs at the most highly contaminated urban sites had a lower diversity of species and ecological functions, compared to less contaminated sites. Food webs at contaminated sites had a simplified structure, and a reduced abundance in prey important for apex predators such as the dipper.

Co-author Professor Steve Ormerod of Cardiff University’s School of Biosciences and Water Research Institute summarised: “Urban river ecosystems in Britain have been on an improving trajectory since at least 1990, but there is still a way to go before we can say that they’ve wholly recovered from well over a century of industrial and urban degradation.

“The ecological pressures on our rivers are multiple, ranging from combined sewer overflows to engineering modifications, and this research adds a new dimension to understanding why they’re not yet at their best,” Ormerod said.

“The slow degradation of some pollutants means that we may have to wait a long time before these chemicals disappear. Perhaps one of the lessons is that we should avoid ecosystem damage in the first place rather than try to solve problems after they occur.”


Windsor, F. et al (2019) Persistent contaminants as potential constraints on the recovery of urban river food webs from gross pollution, Water Research, Volume 163, 15 October 2019, 114858 (open-access)

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