Can science save the Itchen?

The Environment Agency (EA) has launched a critical study of salmon on the Itchen – one of only six chalkstreams in England still supporting the endangered species. The investigation focuses on improving fish passage past barriers and restoring the lower river by Southampton.

In 2022, just 133 salmon returned to the River Itchen to spawn – the lowest number since records began in 1990 and only 20% of the conservation limit, according to the Test & Itchen Association.

Jackie Mellan, EA project manager, said: “The Itchen has really changed in the past 10 years – salmon are at significant risk of extinction, the sea level has risen, and climate change has made floods and low flows more extreme.”

The primary challenge lies at structures such as Woodmill sluice, where sharp changes in water velocity cause smolts to hesitate and bunch up – making them vulnerable to predation. Part of the river has also “breached”, with water branching off the main channel through Riverside Park’s floodplain.

The study, due for completion in October, will examine solutions such as restoring river habitat, improving fish passage and encouraging community engagement. This research forms part of the broader Itchen Salmon Delivery Plan – a collaboration between conservation groups and government agencies.