Photo Credit: Jeremy Shelton / Freshwater Research Centre

Water engineering can help save the Barrydale Redfin


South Africa’s Cape Region is currently blighted by severe drought, putting the last remaining populations of rare Redfin fish at risk. People at SOS partner Cape Critical Rivers work to keep the region’s rivers flowing to save the fish.

The Cape Region is famous as a hotspot of biodiversity, rich in flora and fauna species that are endemic here – that is, they occur nowhere else in the world. Many of these are rare or threatened. For the last three years, this region has been in the grip of a catastrophic drought, putting further pressure on species that are already at risk of extinction. For example, the drought has been very hard on Redfins (genus Pseudobarbus) (video), a genus of 18 closely related, endemic species of fish named for the bright colour of their fins, of which 14 are listed as Endangered or Critically Endangered on the IUCN Red List of Threatened Species™. One of the most at risk is the Barrydale Redfin (P. burchelli) (photo) – Critically Endangered on the Red List -- of which the last known population occurs in the ca. 13-km-long Huis River in the Western Cape Province. Even before the drought, Barrydale Redfins were severely affected by habitat loss, excessive water abstraction for agriculture and domestic use, water pollution, and predation by introduced fish species such as bass and trout.

The Cape Critical Rivers consortium, a partnership between the Endangered Wildlife Trust, the Freshwater Research Centre, CapeNature, and the South African Department of Environment and Nature Conservation, has now used an innovative water engineering solution to restore flow to the Huis River and help save the Barrydale Redfin. This important work was partly funded by an SOS Threatened Species Grant in 2012 to the Endangered Wildlife Trust, followed by a Rapid Action Grant in 2015.

Even in normal years, the flow in the Huis River is much reduced due to water abstraction to supply the nearby village of Barrydale and neighbouring farms. So much water is withdrawn that the isolated pools on which the Barrydale Redfin relies for refuge during the dry months (May-September) risk drying up. Earlier studies, funded by SOS, showed that the canal that draws water from the Huis River was very leaky, resulting in considerable waste. Cape Critical Rivers has now taken the initiative to re-line this canal with concrete, a simple solution that saves water which now gets reallocated to the Huis River, preserving the fish habitat. Furthermore, they hired an engineering firm to design a self-regulating water pressure valve for installation in the canal’s mouth, which optimizes the flow back to the river and thus helps to maintain its water level. Lastly, they have removed non-native alien vegetation from the banks of the Huis River, further increasing the supply of water supply and improving its quality. In short, innovative, simple measures that can help conserve the Barrydale Redfin and its habitat.

“[Cape Critical Rivers] has already shown remarkable successes... It has been an incredible model for the powers of partnership, about bringing together people of different skills and roles to harness greater actions and conservation dividends,” says Christy Bragg, Associate at the Freshwater Research Centre.

The fantastic work of Cape Critical Rivers would not be possible without the support of local people. “Local communities are starting a ‘Friends of the Barrydale Redfin group, clearing litter from banks and spreading the word that a really cool fish lives in the Huis River!” says Martine Jordaan from provincial conservation agency CapeNature.

The Barrydale Redfin is just one of over 250 threatened species supported by over 100 projects in the SOS programme. Each project offers a wealth of practical lessons and insights into conservation action across numerous taxonomic groups and challenges. Explore the SOS interactive project map and sign up for our newsletter to keep up to date on further news from our grantees and visit the project page to learn more.

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