Wild salmon in Hampshire’s chalk streams face multiple threats, including rising water temperatures, degradation of habitat, sewage and urban and agricultural pollution.
There are thought to be only 220 chalk rivers in existence – the majority of which are in southern England.
The salmon bury their eggs in the waterways, known for their clear water and gravelly bottoms.
The fish bury their eggs in fragile gravel nests known as redds and shoals of juvenile salmon start their journey from the rivers to the sea each spring.
After often years at sea, adult Atlantic salmon swim thousands of miles to return to the chalk streams where they were born.
Hampshire and Isle of Wight Wildlife Trust figures showed just 133 adult salmon were recorded returning to spawn in 2022 – the lowest figure since monitoring began in 1990.