Conservationists reintroduce endangered Witvis into Berg River

The Freshwater Research Centre in Cape Town recently partnered with the Ford Wildlife Foundation, among others, to re-introduce the Witvis into the Berg River.

The Witvis, also known as the Berg-Breede Whitefish, became extinct in the river in the 1990s due to excessive pollution and increased predation by smallmouth bass.

It is currently classified as endangered on the International Union for Conservation of Nature’s (IUCN) global red list of threatened species.

However, 30 years later various stakeholders, including the Western Cape Government’s Berg River Improvement Plan as well as the Freshwater Research Centre non-profit organisation, has worked tirelessly to revive the Berg River’s ecosystem.

This was achieved by reducing pollution through collaboration with farmers, encouraging them to avoid disposing of pesticides and other harmful substances into the river, and by removing invasive species.

On 13 March researchers from the Freshwater Research Centre and representatives of the Ford Wildlife Association administered the release of over a 100 Witvis into the Berg River at the Berg River Resort outside of Paarl.

These Witvis were bred at nearby dams, such as at Babylonstoren and Boschendal and caught with nets whereafter a number of the fish were tagged and released into the river.

“To track the fish effectively, the team is tagging 15-20% of the released individual fish with passive integrated transponder (PIT) tags – small barcodes that allow researchers to identify and monitor them in future surveys. By analysing the number of tagged fish recorded, along with their health and growth, these scientists will gain valuable insights into their survival rates and overall success in the Berg River,” according to a press release by the Ford Wildlife Association.

The tagged fish will be monitored annually by the Freshwater Research Centre, specifically through its Bringing Back the Witvis programme, which was established to reintroduce the species into the Berg River, where it is extinct, and to support its declining population in the Breede River.

The reason for the reintroduction

According to Dr Jeremy Shelton, a freshwater conservation biologist at the Freshwater Research Centre, one reason for the reintroduction of the Witvis into the Berg River is the decline of smallmouth bass, which preyed on the species before the 1990s.

Shelton noted that the cause of the bass decline remains unknown. He said the research centre also observed an increase in sharptooth catfish in the river, though whether they will prey on the Witvis is yet to be determined.

Another reason is the decline in pollution.

• “For over 30 years, Ford South Africa has actively participated in wildlife and ecosystem conservation efforts in South Africa and Sub-Saharan Africa. The Ford Wildlife Foundation was established in 2014 and currently supports 28 projects across South Africa and one project in Mozambique. This comprises 17 conservation projects, seven research projects and five environmental education projects. A key aspect of the Ford Wildlife Foundation’s initiatives involves the provision of locally manufactured Ford Ranger Double Cab 4x4s to support partner organisations,” the Ford Wildlife Association said.