science · 12 November 1974 · 50 years ago
In 1974, a salmon was discovered in the River Thames, England, for the first time since 1833. The 8-lb 4½-ozoz female was discovered entangled in the protective nets around West Thurrock power station.* The find was so surprising that the fish was sent to the British Museum for positive identification. Victorian era sewage and factory waste had polluted the once thriving salmon river, and by 1849 the fish had disappeared. On 7 Jul 1855, Michael Faraday wrote in The Times regarding the putrid state of the Thames. From 1961, improved sewage treatment and limits on industrial discharges gradually brought about a cleaner river. Since the salmon's life cycle requires a high standard of water quality, the species indicates environmental quality.
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