A salmon has been caught near Basel, leading to hopes that the fish could be making a return to Swiss waters.
The 91 centimetre-long female salmon was reeled in from the Birs, a tributary of the River Rhine, photographed and then released, the Federal Environment Office said on Wednesday.
Switzerland's salmon population was wiped out in the 1950s after hydroelectric plants were built on the River Rhine, preventing the fish from reaching spawning zones.
The size of the caught fish indicates that it could have originated in the Atlantic and reached Basel by swimming via navigational locks. It also could have resulted from a breeding programme in which 50,000 eggs a year have been released into Basel's rivers.
Water in the River Rhine had greatly improved since the 1980s and steps were taken to restore its formerly rich ecosystems, the office said.
The office added that it showed that salmon could become more regular in Switzerland if hydroelectric plants were equipped with filters for fish to pass through.