Monitoring the TRADOUW redfin: A Concerning Decline

Since 2012, several organisations have been monitoring the Tradouw redfin Pseudobarbus burchelli population and the overall health of the Huis and Tradouw river systems. From 2018 onwards, the Grootvadersbosch Conservancy (GVB) has played a leading role through various freshwater conservation initiatives—most notably the Grootvadersbosch Aquatic Species Protection Project (GASPP), implemented in partnership with CapeNature and funded by the Table Mountain Fund. Although GASPP concluded in 2022, one of its key achievements was the development of local knowledge and capacity for long-term monitoring. GVBC has since continued annual monitoring in April/May and October/November across 59 sites between Riversdale and Swellendam.

A Tradouw Redfin being measured before returning it to the Huis River

GVBC recently hosted a workshop focused on developing a species action plan—funded by the IUCN Species Survival Commission—which will inform the drafting of a Biodiversity Management Plan (BMP) for the Barrydale redfin. Once this BMP is approved, the Minister of Environment will appoint a lead agency and publish the plan in the Government Gazette. The BMP then becomes binding, providing additional legal protection for the species. Furthermore, the publication of a BMP and the signing of a Biodiversity Management Agreement between qualifying taxpayers and the Minister may unlock a tax incentive. This incentive allows for the deduction of qualifying conservation and maintenance expenses from taxable income—effectively reducing tax liability and encouraging conservation efforts.

Dr Jordaan discusses the concerning trends in the population numbers of the Tradouw redfin

During our first workshop in March, Dr Martine Jordaan from Cape Nature commented on a noticeable decline in redfin numbers in the Tradouw Pass and emphasised the need for more intensive sampling to confirm these trends. In response, a comprehensive fish monitoring survey was conducted by GVBC over a 7 km stretch of the Tradouw Pass, in collaboration with the Gouritz Cluster Biosphere Reserve. This took place in April 2025—our usual monitoring period—but involved a more extensive effort, using eight nets across five sites (as opposed to the usual one or two nets at one site). The results were concerning- not a single redfin was recorded across all the sites. This represents a significant decline when compared with past surveys and points to increasing pressure on this river system.

Historically, eels have also been found in the system, but none were detected in the recent survey, despite. Surprisingly, very few invasive fish were found either—just two juvenile tilapia at one site. These findings raise critical questions about the river’s current ecological state. What could be occurring downstream that is preventing eel migration? And what’s driving the decline in redfin populations in the Tradouw Pass? Could it be linked to a recent flood event or sudden changes in water temperature? These are pressing questions that require further investigation and ongoing monitoring. ​These results are consistent with Dr Jordaan’s observations over the past decade: a steady decline in the redfin population, particularly in the Tradouw system. This highlights the increasing importance of the Huis River system for the species' survival and underscores the need for a robust management plan to ensure the survival of the species.
​
On a more positive note, the species has officially been named as Pseudobarbus burchelli (common name Tradouw redfin) and the details are updated in the new Field Guide to the Freshwater Fishes of Southern Africa (Skelton, 2024). This formal recognition strengthens the case for its conservation and brings renewed attention to the urgent need for action.

Longfin eels (Anguila mossambica) are often found in the Tradouw pass but were not observered in the most recent samplying