{"id":85026,"date":"2022-06-08T16:56:01","date_gmt":"2022-06-08T16:56:01","guid":{"rendered":"https:\/\/www.bgs.ac.uk\/?p=85026"},"modified":"2024-02-27T12:18:05","modified_gmt":"2024-02-27T12:18:05","slug":"climate-change-and-human-exploitation-linked-to-historic-decline-in-atlantic-salmon","status":"publish","type":"post","link":"https:\/\/www.bgs.ac.uk\/news\/climate-change-and-human-exploitation-linked-to-historic-decline-in-atlantic-salmon\/","title":{"rendered":"Climate change and human exploitation linked to historic decline in Atlantic salmon"},"content":{"rendered":"\n
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New research has revealed that an abrupt change in climate conditions in the North Atlantic around 800 years ago played a role in a decline in Atlantic salmon populations returning to rivers. Human exploitation reduced their populations still further.<\/p>\n\n\n\n

Using state-of-the-art geochemistry, a team of scientists has discovered that large-scale changes in the marine habitat, brought on by a transition from a warm to a cold climate and what is now known as the Little Ice Age (approximately 1300 to 1850 CE), corresponded with a decline in salmon in the River Spey, Scotland. The study, published in the international journal The Holocene<\/em>, was led by the University of Southampton, working with BGS.<\/p>\n\n\n\t\t\t

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These results can help us understand some of the controls on salmon populations prior to and during major human exploitation.<\/p>\n

Our study shows that historically, beavers \u2013 common in Scotland hundreds of years ago \u2013 do not appear to have significantly impacted salmon numbers. This is very relevant today, as the animals are being reintroduced to UK rivers and a debate continues about their potential impact on migratory species like salmon.<\/p>\n

Prof David Sear, professor of geography and environmental science at the University of Southampton and lead author of the study.<\/strong><\/p>\n\t\t\t\t<\/div>\n\t\t\t<\/blockquote>\n\t\t\t\n\n\t\t\t

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This research benefited from state-of-the-art geochemistry which enabled us to fingerprint salmon abundance over hundreds of years. We show that climate has been an important influence of salmon numbers, which is very relevant today due to the speed of climate change.<\/p>\n

Prof Melanie Leng, BGS, co-author.<\/strong><\/p>\n\t\t\t\t<\/div>\n\t\t\t<\/blockquote>\n\t\t\t\n\n\n

Atlantic salmon lay their eggs in the gravels of headwater streams, where their young live for a year or two before migrating out to sea. Here, they feed and grow into adults, eventually returning to the river to spawn, where many then die. The sperm, eggs and carcasses are rich in marine nutrients, which can be detected in sediment hundreds of years later.<\/p>\n\n\n\n

Using core samples from Loch Insh on the River Spey, the scientists collected and measured marine-derived nutrients (MDNs), which give an understanding of the historic population levels of salmon. The team also examined a 150-year record of net-catch data from the lower Spey to help calibrate the MDN record.<\/p>\n\n\n\n

The scientists were able to construct a 2000-year record of both salmon-derived nutrients and variations in climate conditions.<\/p>\n\n\n\n

The findings show:<\/p>\n\n\n\n