How I’m protecting Clanwilliam sandfish
Cecilia Cerrilla’s PhD project is to protect a tiny species of fish from predatory bass
To lay eggs, Clanwilliam sandfish (Labeo seeberi) swim upstream to gentler, shallower tributaries of the Doring/Olifants river system in the Western Cape and Northern Cape provinces of South Africa. Local people say it was once an epic event: the water seemed to change colour as thousands of sandfish migrated upstream. Now, however, those numbers have shrunk to dangerous levels.
That’s where I come in. My PhD at South Africa’s University of Cape Town is a collaboration with the Saving Sandfish project, run by a non-governmental organization called the Freshwater Research Centre in Cape Town — so I am also a conservationist.
Human activity, climate change and thirsty invasive plants, are draining the rivers. As newly hatched sandfish try to swim downstream, they now get stuck in shallow pools, making them vulnerable to predators such as bass species introduced into the river system for sport fishing in the 1900s.
The sandfish population has declined by more than 90% since we began keeping count in 2013. They’re now classified as endangered by the International Union for the Conservation of Nature.
When the river starts to dry up, we scoop out young sandfish and put them into buckets of water, then move them by truck to one of six pre-prepared nurseries donated by local people. In this photo, I’m lifting a fish from one of those reservoirs. The support from local people is amazing.
Once the sandfish are large enough to be less threatened by the bass, we return them to the wider ecosystem.
We’re at an early stage, but the data so far show the project has been successful. We’ve rescued some 36,000 young sandfish over the past three years and have released almost 3,000. Last year, we got 77 readings from fish coming back from the group we released into the wild. This year, 222 have come back so far. I’m looking forward to adding to those numbers next year.
Nature 624, 694 (2023)
doi: https://doi.org/10.1038/d41586-023-04031-0
This story originally appeared on: Nature - Author:Jack Leeming
