Clanwilliam sand fish: Supplied: Jeremy Shelton
From the tiny galaxiids of South Africa to the 2m-long Nile perch, Africa’s extraordinary biodiversity of freshwater fish have evolved to thrive in the various habitats in the geographically, climatically and topographically diverse continent.
They are found in sediment-rich rivers, shallow ponds, the great lakes, caves, canyons, mountain streams and forests. Yet they are often overlooked in global conservation conversations.
This is according to a new report on Africa’s forgotten fish, which WWF Africa released in the lead-up to the Ramsar COP15 — a major United Nations wetlands conference — which gets under way in Zimbabwe from 23 July. There, countries will set the course for safeguarding and restoring vital freshwater ecosystems.
The report reveals that 26% of Africa’s assessed freshwater fish species are threatened with extinction, but there are large data gaps so the true number is likely to be much higher.
Africa is a global hotspot of freshwater fish diversity, home to more than 3 200 species — more than a quarter of the world’s total freshwater fish. It’s also a “hotspot of risk”, said Eric Oyare, the freshwater lead for WWF Africa.
“When these fish disappear, we lose much more than species: we lose food security, livelihoods, ecosystem balance, and resilience to floods and droughts. These declines are a red flag for the broader health of Africa’s freshwater ecosystems, which are the very life support systems for people and nature.”
But these lifelines are collapsing under the weight of multiple threats. These include habitat destruction from dams, deforestation, mining and land conversion; pollution from agriculture, urban areas and industry; invasive species and overfishing, including with destructive gear like mosquito nets; and climate change, which alters rainfall patterns, dries out rivers and heats lakes.
Freshwater fish populations are in freefall across the continent. In the Zambezi floodplain, catches of key species have dropped by up to 90%. At the same time, Lake Malawi’s “chambo” tilapia, a staple food and national symbol featured on the Malawian kwacha, has declined by 94%.
When people think of the continent’s biodiversity, few consider Africa’s astonishing diversity of freshwater fish, “yet they have swum through the continent’s communities and cultures for millennia, and are still critical to the daily lives of tens of millions of people — as well as to the overall health of their freshwater ecosystems”, said the report.
Africa’s rivers, lakes and wetlands are home to at least 3 281 freshwater fish species — a
figure that includes Madagascar and “that is almost certainly a significant underestimate”.
This is because so many species have not yet been described by science and new species are being discovered in Africa every year — 28 during last year alone.
These fish are vital for people and nature, supporting ecosystem functionality and the provision of ecosystem services across the continent, enhancing food security and nutrition for millions. They support countless livelihoods, particularly in vulnerable communities and landlocked countries.
More than three million tonnes of freshwater fish are caught each year on the continent, representing nearly 30% of the reported global freshwater fish catch. This figure, too, “is “definitely a major underestimate”, the report said, again because of a lack of data, especially for small-scale fisheries.
The continent boasts 12 of the top 25 inland fish producing countries in the world, with Uganda coming in highest in sixth place. The annual catch feeds the highest per capita consumption of freshwater fish of any continent in the world and employs more than three million people.
It plays a central role in the cultures of many indigenous peoples. And some fishes are economically important either as the lure for recreational anglers or as dazzling aquarium fishes.
Weird and wonderful
The continent’s freshwater fish are much more than just food or economic resources. The report cited how possibly the most famous of Africa’s freshwater fishes are the incredibly diverse cichlids, with at least 1 600 endemic species found in the Great Lakes – Victoria, Tanganyika, and Malawi.
“These cichlids are one of the most spectacular examples of speciation in the world and provide scientists with a unique opportunity to better understand the drivers of species evolution.”
Livingstone’s cichlid or kalingono from Lake Malawi has developed a unique hunting style; it plays dead to attract other fish to eat it, then it turns the tables by “coming alive” and eating the would-be predator.
There are “so many other weird and wonderful species to discover”, the report said, like Africa’s elephant fishes, which use electrical pulses to communicate with others about sex, size, predators and prey.
The cuckoo catfish gorges itself on the eggs of cichlids in Lake Tanganyika. “Like its famous avian namesake, this fish tries to palm off parental care on an unsuspecting species. The cuckoo catfish does this by creating chaos at spawning time and confusing unsuspecting female cichlids into scooping up its spawn, which the cichlids subsequently brood in their mouths.”
The African tigerfish can leap from the water to catch barn swallows in flight while the African lungfish breathes air and can survive years buried in mud during droughts. The ancient bichirs are often referred to as “living fossils” for their lineage that predates the dinosaurs.
Under-reported, undervalued and under pressure
But despite their dazzling diversity and critical importance, the continent’s freshwater fishes have remained “largely invisible” to decision-makers with the benefits they contribute “hidden and ignored” — and are now facing increasing threats to their survival.
Globally, freshwater species populations are in freefall – crashing 85% since 1970. Nearly a quarter of the world’s freshwater fish species are threatened with extinction. Africa’s freshwater fishes are no exception.
The report noted that of the 3 281 freshwater fish species, 712 are classified as threatened — with 170 listed as critically endangered, 243 listed as endangered and 299 listed as vulnerable.
But the true number is higher because 536 of the continent’s assessed freshwater
fish are classified as data deficient, “which means they are so poorly known that their threat status can’t be assessed”.
The IUCN Red List of Threatened Species classifies nine freshwater fishes as extinct — three from Morocco, two from Madagascar and one each from Kenya and Tanzania, Rwanda, Tunisia and Lake Malawi.
“However, the true number is likely to be significantly greater. For example, many species have almost certainly been lost in Lake Victoria alone.”
The report said: “When we tip the scales by drastically reducing freshwater fish populations, we undermine the functioning of freshwater ecosystems — our very life support systems. The decline in freshwater fish populations is the clearest indicator of the damage we have done — and are still doing — to Africa’s rivers, lakes and wetlands.
“And that collapse of aquatic ecosystems across Africa only exacerbates the continent’s freshwater fish crisis. Freshwater fishes need healthy freshwater ecosystems. And so do we. But we’re losing them both far too fast.”
Spawning protection
The report said that very rarely are the full economic and social values of freshwater fishes and fisheries factored into decisions about hydropower dams, the draining of wetlands and dredging for navigation or sand mining, for example.
“However, there are indications that some decision-makers are finally starting to take the fate of freshwater ecosystems and fishes into account – and that the momentum for action is building.”
African countries signed up to the Kunming-Montreal Global Biodiversity Framework in December 2022, which explicitly includes the commitment to protect 30% of inland waters and restore 30% of degraded inland waters.
The report said this ambitious agreement paves the way for a new approach to safeguard freshwater biodiversity, highlighted in the country-led Freshwater Challenge.
Championed by the Democratic Republic of the Congo, Gabon and Zambia, 20 countries on the continent have already joined the challenge — the largest freshwater protection and restoration initiative in history. Meanwhile, 51 countries are members of the Ramsar Convention on Wetlands.
WWF is urging African countries to adopt the Emergency Recovery Plan for Freshwater Biodiversity as a framework for action. This science-based, practical roadmap has been developed by leading experts to restore the health of freshwater ecosystems and the communities that rely on them.
The plan outlines six urgent actions including letting rivers flow more naturally; improving water quality in freshwater ecosystems; protecting and restoring critical habitats and species; ending unsustainable resource use; preventing and controlling invasive non-native species; safeguarding free-flowing rivers and removing obsolete barriers.