Freshwater fish highlight escalating climate impacts on species - IUCN Red List
Dubai, United Arab Emirates, 11 December 2023 (IUCN) – Climate change threatens a growing number of species, from Atlantic salmon to green turtles, today’s update to the IUCN Red List of Threatened Species™ reveals. The update, released at the COP28 UN climate conference in the United Arab Emirates, also includes the first global freshwater fish assessment, and highlights the impact of illegal logging and trade on mahogany. Conservation efforts have successfully brought two antelope species back from the brink of extinction, but changing climatic conditions could undermine their future.
The IUCN Red List now includes 157,190 species, of which 44,016 are threatened with extinction.
“Climate change is menacing the diversity of life our planet harbours, and undermining nature’s capacity to meet basic human needs,” said Dr Grethel Aguilar, IUCN Director General. “This IUCN Red List update highlights the strong links between the climate and biodiversity crises, which must be tackled jointly. Species declines are an example of the havoc being wreaked by climate change, which we have the power to stop with urgent, ambitious action to keep warming below 1.5 degrees Celsius.”
“Today’s update to the IUCN Red List shows the power of coordinated local, national and international conservation efforts. Success stories such as that of the scimitar horned oryx show that conservation works. To ensure the results of conservation action are durable, we need to decisively tackle the interlinked climate and biodiversity crises,” said IUCN President Razan Al Mubarak.
State of the world’s freshwater fish species
Today’s update completes the first comprehensive assessment of the world’s freshwater fish species, revealing that 25% (3,086 out of 14,898 assessed species) are at risk of extinction. At least 17% of threatened freshwater fish species are affected by climate change, including decreasing water levels, rising sea levels causing seawater to move up rivers, and shifting seasons. This compounds threats from pollution, which impacts 57% of freshwater fish species at risk of extinction, dams and water extraction, which affect 45%, overfishing, which threatens 25%, and invasive species and disease, which harm 33%. For example, the large-toothed Lake Turkana robber (Brycinus ferox) – an economically important species in Kenya – has moved from Least Concern to Vulnerable on the IUCN Red List, due to overfishing, climate-change driven habitat degradation and dams reducing freshwater entering the lake.
“Freshwater fishes make up more than half of the world’s known fish species, an incomprehensible diversity given that freshwater ecosystems comprise only 1% of aquatic habitat. These diverse species are integral to the ecosystem, and vital to its resilience. This is essential to the billions of people who rely upon freshwater ecosystems, and the millions of people who rely on their fisheries. Ensuring freshwater ecosystems are well managed, remain free-flowing with sufficient water, and good water quality is essential to stop species declines and maintain food security, livelihoods and economies in a climate resilient world,” said Kathy Hughes, Co-Chair of the IUCN SSC Freshwater Fish Specialist Group.
The Atlantic salmon (Salmo salar) has moved from Least Concern to Near Threatened, with new evidence showing the global population decreased by 23% between 2006 and 2020. Atlantic salmon are now restricted to a small portion of the rivers they inhabited a century ago across northern Europe and North America, due to multiple threats over the course of their long-distance migrations between freshwater and marine habitats. Climate change affects all stages of the Atlantic salmon’s life cycle, influencing the development of young salmon, reducing prey availability and allowing invasive alien species to expand their range. Dams and other barriers block access to spawning and feeding grounds, while water pollution and sedimentation, primarily from logging and agriculture, lead to higher mortality of young salmon. Breeding with escaped farmed salmon threatens many wild populations, and may weaken their ability to adapt to climate change. Mortality due to salmon lice (Lepeophtheirus salmonis) from salmon farms is also of great concern. A significant rising threat is the invasive Pacific pink salmon (Oncorhynchus gorbuscha), which is spreading rapidly across northern Europe.
Central South Pacific and East Pacific green turtles at risk of extinction
The Central South Pacific and East Pacific green turtle (Chelonia mydas) populations are respectively Endangered and Vulnerable to extinction, according to today’s IUCN Red List update. Climate change is a growing threat to green turtles throughout their life cycle, as high temperatures result in lower hatching success, rising sea levels threaten to flood nests and drown the young, and the seagrasses that green turtles eat are susceptible to ocean warming and changes in currents due to extreme weather. A major cause of green turtle mortality throughout these regions is incidental bycatch in industrial and artisanal fishing. Numbers have also decreased as people harvest green turtles and their eggs for their own consumption or to sell at markets.
Conservation successes: the scimitar-horned oryx and the saiga antelope
The scimitar-horned oryx (Oryx dammah) has moved from Extinct in the Wild to Endangered on the IUCN Red List, thanks to conservation efforts that have reintroduced the species to Chad. Once common across the Sahel region of Africa, this antelope disappeared from the wild by the end of the 1990s. Increasingly intense poaching with modern firearms and motor vehicles, plus extreme droughts every decade, led to its demise in the twentieth century. Today, poaching levels are rising mainly for subsistence and trade, amidst high levels of poverty and food insecurity. Following a long-term international project, the scimitar-horned oryx is now established in the wild, with at least 140 mature individuals ranging freely in the Ouadi Rimé-Ouadi Achim Faunal Reserve in Chad and 331 calves born there by 2021. The full support of national authorities and local communities has played an essential part in the project’s success, and the species’ survival depends on continued protection against poaching. Climate change in the Sahel remains a possible threat to the future of the scimitar-horned oryx.
The Red List status of the saiga antelope (Saiga tatarica), which lives across Kazakhstan, Mongolia, Russia and Uzbekistan, has improved from Critically Endangered to Near Threatened. The population in Kazakhstan, home to 98% of all saigas, increased by 1,100% between 2015 and 2022 and reached 1.3 million in May 2022. The species is very susceptible to disease outbreaks, suffering mass mortality events in 2010, 2011, 2015 and 2016. The high death rate in 2015 is understood to have been triggered by abnormally high temperatures and humidity, conditions expected to become more frequent with climate change. Combined with growing numbers of domestic livestock, which increase the chance of disease transfer, the risk of future disease outbreaks causing significant mortality remains high. Poaching for horns and meat has also caused major saiga declines. The improvement in status is the result of extensive anti-poaching measures, along with education programmes, training of customs and border officials, and action against illegal sale in consumer countries. This situation is entirely dependent on continued enforcement of anti-poaching measures and trade controls.
“The scimitar-horned oryx is the fourth large mammal to have been successfully reintroduced to the wild in the past 100 years. The success of this project and the dramatic recovery of the saiga are the results of strategic vision, strong government commitment and investment, technical support from non-governmental organisations and scientific experts, and collaboration with local communities,” said Dr David Mallon, Co-Chair of the IUCN SSC Antelope Specialist Group.
Continued demand for big leaf mahogany poses threat
Big leaf mahogany (Swietenia macrophylla), one of the world’s most commercially sought-after timber trees, has moved from Vulnerable to Endangered on the IUCN Red List. New information has revealed that numbers across Central and South America have reduced by at least 60% over the past 180 years, due to unsustainable harvest of this valuable timber from the wild, and agricultural and urban encroachment into the tropical forests where it grows. Mahogany continues to be sought after across the US, Western Europe and China for making high quality furniture, veneers, decorative and ornamental features and musical instruments. Despite being protected under national and international legislation and concerted efforts by all range states, illegal logging and trade continues due to this high demand. Greater resources to manage protected areas and to address the illegal timber trade are urgently needed. Models show that climate change is predicted to make some of big leaf mahogany’s current habitat unsuitable.
“This year's IUCN update sees thousands of trees added to the IUCN Red List, many of which are timber species. These trees are often keystone species in forests as well as important for national and local economies. However, often they are at risk of extinction from unsustainable harvest. It is essential we support botanic gardens to protect and propagate threatened timber species in ex-situ collections and provide more resources towards making informed decisions on their sustainable use and trade,” said Megan Barstow, Conservation Officer at Botanic Gardens Conservation International.
“Biodiversity data is the lens through which we view the urgent narrative of conservation,” said Dr Sean T. O’Brien, President and CEO of Nature Serve. O’Brien continued, “Today’s Red List update shines a light on the plight of freshwater fish, one of many groups facing multiple threats intensified by a changing climate. Yet, in the face of complexity, we possess the tools to act. Let us use our knowledge and resources to safeguard biodiversity for the generations that follow.”
“The climate and biodiversity crises are two sides of the same coin. On the one hand, climate change is one of the drivers of documented declines in animals, fungi and plants, but on the other, the resilience of nature through recovery and regeneration of species and ecosystems is our most powerful ally to combat accumulation of greenhouse gases in the atmosphere. This Red List update illustrates both the climate-related mechanisms behind declines of fishes and sea turtles, as well as the recovery of scimitar-horned oryx and saiga through proactive conservation action,” said Dr Jon Paul Rodríguez, Chair of the IUCN Species Survival Commission.
“It is shocking that one quarter of all freshwater fish are now threatened with extinction and that climate change is now recognised as a significant contributing factor to their extinction risk, which was also recently reported to be a serious emerging threat to amphibians,” said Dr Barney Long, Re:wild's Senior Director of Conservation Strategies. “It is critical that we better safeguard our freshwater systems as they are not only home to precious and irreplaceable wildlife, but also provide humans with so many services that only the natural world can.”
"This update contains assessments of over 80 plant species known from only Ethiopia and is the first fruit of a collaboration between Addis Ababa University (AUU), the Ethiopian Biodiversity Institute and the Royal Botanic Gardens, Kew. Funded by the UK Global Centre for Biodiversity and Climate (GCBC), it highlights the importance of international partnerships in tackling the biodiversity crisis," said Jack Plummer, Plant Assessment Coordinator at Royal Botanic Gardens, Kew.
"This is an important step towards completing assessments for all Ethiopia’s endemic plant species, over 450 known to date. Endangered species highlighted include Convolvulus vollesenii, a bright blue-flowered creeper, and Cladostigma nigistiae, a white-flowered climber with striking silvery foliage," said Professor Sebsebe Demissew, Professor of Plant Systematics and Biodiversity at Addis Ababa University, who co-authored many of these IUCN Red List assessments.
“At Senckenberg we are honoured to become a partner of the global IUCN Red List. In the era of Anthropocene biodiversity loss, it is important for natural history museums and working taxonomists to take a strong role not just to document biodiversity but to protect species,” said Professor Julia Sigwart, Chair of the Marine Invertebrate Red List Authority and Head of Malacology at Senckenberg Research Institute and Museum Frankfurt.
“The outstanding progress made with scimitar-horned oryx in Chad has shown that local conditions in their original landscape are currently very favourable and the response of the local communities has also been notably positive,” said Tim Wacher, Senior Conservation Biologist at the ZSL, who has supported post-release monitoring efforts. “The results are the outcome of prolonged international conservation efforts for the species – including the breeding of oryx for reintroduction at ZSL’s own conservation zoo - coupled with the vision and resources to implement re-introduction quickly and at scale once careful in-depth preparation was completed.”
“Money raised by WildFish supporters enabled this reassessment of Atlantic salmon stocks across the world. The outcome for UK populations, although not unsurprising, is very grim. We need the UK government to give environmental regulators the mandate and resources to address the myriad of issues threatening the survival of Atlantic salmon. The alternative is we risk losing them from our waters altogether,” said Nick Measham, Chief Executive at WildFish.