Climate change and human exploitation linked to historic decline in Atlantic salmon
New research reveals that both a change in climate and human exploitation played a role in a decline in North Atlantic salmon populations.
08/06/2022 By BGS PressNew 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.
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, was led by the University of Southampton, working with BGS.
These results can help us understand some of the controls on salmon populations prior to and during major human exploitation.
Our study shows that historically, beavers – common in Scotland hundreds of years ago – 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.
Prof David Sear, professor of geography and environmental science at the University of Southampton and lead author of the study.
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.
Prof Melanie Leng, BGS, co-author.
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.
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.
The scientists were able to construct a 2000-year record of both salmon-derived nutrients and variations in climate conditions.
The findings show:
- bigger salmon populations (inferred from changes in MDNs) in the past reduced during a cooling climate at around the same time humans began to exploit them, leading to a major decline in the fish over the last 800 years
- larger salmon populations in the past occurred at a time when rivers were also inhabited by beavers, which suggests migratory fish are capable of co-existing with beavers; this is an important concern of anglers around current beaver reintroductions
- migratory fish, such as salmon, bring marine nutrients into our nutrient-poor upland rivers and probably represented a major boost to aquatic and wetland ecosystems in the past, with a decline in nutrients negatively affecting these ecosystems today
It is the first study to use MDNs to measure Atlantic salmon, although the method has previously been used for Pacific salmon in north-west USA and Canada.
Relative topics
Related news
UK legacy geothermal catalogue released in digital format for the first time
18/04/2024
BGS has released the first digital version of the UK legacy geothermal catalogue of subsurface temperature measurements, rock thermal conductivity measurements and heat flow calculations.
New research supports conservation of fallow deer across Europe
16/04/2024
New research has combined zooarchaeology and ancient and modern biomolecular datasets to reveal new understandings into the history and projections of fallow deer.
BGS signs memorandum of understanding with Serviço Geológico do Brasil
10/04/2024
The partnership will advance the two organisations’ shared interests in mineral research and geoscience to help benefit society.
World Mineral Production 2018 to 2022 is now available
09/04/2024
The latest edition of World Mineral Production has been released.
New underground observatory open for research
09/04/2024
Construction has been completed on the Cheshire Observatory and the facility is now open for research activities.
BGS leads update to maps of the Earth’s magnetic field
04/04/2024
The International Geomagnetic Reference Field, used for navigation on mobile phones and in space, is updated every five years.
UK bidding to host the International Geological Congress 2028
18/03/2024
BGS has partnered with the Geological Society of London and the Scottish Geology Trust to develop a bid to host the 38th International Geological Congress in Glasgow in 2028.
BGS to lead a new research project on microplastic occurrence in springs
06/03/2024
BGS has been awarded a two-year research project to undertake the first assessment of microplastic occurrence in springs in the UK.
Local MP helps BGS launch a ‘living laboratory’
05/03/2024
BGS is implementing a low-carbon heating system to help meet its net zero targets and provide data to the public.
Scientists produce first record of environmental data off coast of Hawai’i
01/03/2024
An international team of researchers, including BGS geoscientists, have succeeded in acquiring a continuous record of environmental data using fossilised coral from Hawai’i.
BGS data product licence fees to rise
01/03/2024
New direct licence fees to be introduced from 1 April 2024.