Water supply development could be jeopardising fish conservation

We all know rivers need water, but an investigation in the US Midwest shows how we use that supply could have a huge impact on the health of vulnerable ecosystems.  

The new research focuses on the Upper and Lower Colorado River basins, systems known for high levels of seasonal diversity, including streamflow and water temperature. The behaviour and development of native fish species is dictated by these variations, for example periods of wet weather during the spring snowmelt leading to higher water levels and increasing numbers of fish in the river. 

However, these inhabitants are becoming ‘decoupled from that natural cycle’ as more stretches of the waterway are used for human-related purposes, such as water supply to towns and cities, or boosting stock of non-native fish for sport. According to a study by the College of Natural Resources, Utah State University, this negatively impacts health and prevalence of species naturally found in the area through the resulting reduction in flow. 

‘The bottom line is that everyone knows fish need water, and most people who study or manage fishes know that complex habitat required by native fish is created and maintained by adequate river flows, or a natural flow regime,’ said Phaedra Budy, co-author of the report.

‘The White River of Colorado and Utah is a perfect example of such a natural river; it is the only tributary of the four considered in our research that still has a natural flow regime and it is the only tributary of the middle Green River with abundant complex fish habitat and a thriving native fish community,’ Budy continued. ‘Nonetheless, society continues to manage our desert rivers as if we think that fish don’t need water. If we continue down this path, we will watch native fishes, some of which are found nowhere else on Earth, blink off the planet.’ 

In related news, waterways in England have been found to contain a ‘chemical cocktail‘ of sewage, slurry and plastic, damaging both flora and fauna.

Photo credit: Gert Boers