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How the Atlantic herring adapted to the brackish water of the Baltic Sea

Phys · · 695 words · By Uppsala University
Environmental Conservation Food Security Evolutionary Adaptation

Researchers from Uppsala University published a study in PNAS identifying four specific genes that allowed Atlantic herring to adapt to the low salinity of the Baltic Sea. The findings suggest the Baltic herring may be a distinct species and highlight its importance to the regional ecosystem and food security.

open_in_new Read the original article: https://phys.org/news/2026-05-atlantic-herring-brackish-baltic-sea.html

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20%
Propaganda Score
confidence: 95%
Minor concerns. Some persuasive language detected, but largely factual.

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Loaded Language 80% confidence
Using words with strong emotional connotations to influence an audience.

fact_checkFact-Check Results

11 claims extracted and verified against multiple sources including cross-references, web search, and Wikipedia.

info Single Source 5
verified Verified By Reference 3
help Insufficient Evidence 2
schedule Pending 1
verified
“A new study by researchers from Uppsala University and other institutions, published in the journal PNAS, shows that mutations in four specific genes were particularly important [to the Atlantic herring's adaptation to the Baltic Sea].”
VERIFIED BY REFERENCE
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wikipedia NEUTRAL — There exist a variety of speculative proposals that real-world events could have inspired Plato's fictional story of Atlantis, told in the Timaeus and Critias. While Plato's story was not part of the …
https://en.wikipedia.org/wiki/Proposed_locations_for_Atlanti…
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wikipedia NEUTRAL — Viking expansion was the historical movement, beginning in the 8th century, which led Vikings to sail most of the North Atlantic, reaching south as far as North Africa and east as far as Russia, and t…
https://en.wikipedia.org/wiki/Viking_expansion
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wikipedia NEUTRAL — The gray whale (Eschrichtius robustus), also known as the grey whale, is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of 14.9–15.2 m (49–50 ft), a weig…
https://en.wikipedia.org/wiki/Gray_whale
+ 3 more evidence sources
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“The Baltic Sea emerged after the last glaciation and has existed for only about 8,000 years.”
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wikipedia NEUTRAL — The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North and Central European Pl…
https://en.wikipedia.org/wiki/Baltic_Sea
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wikipedia NEUTRAL — The Baltic Sea anomaly is a feature visible on an indistinct sonar image taken by Peter Lindberg, Dennis Åsberg and their Swedish OceanX diving team while treasure hunting on the floor of the northern…
https://en.wikipedia.org/wiki/Baltic_Sea_anomaly
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wikipedia NEUTRAL — The Baltic states or the Baltic countries is a geopolitical term encompassing Estonia, Latvia, and Lithuania. All three countries are members of NATO, the European Union, the Eurozone, the Baltic Asse…
https://en.wikipedia.org/wiki/Baltic_states
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“the herring is one of the few Atlantic fishes that have successfully adapted to the low salinity of the Baltic Sea.”
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wikipedia NEUTRAL — The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about 85,133,000 square kilometers (32,870,000 sq mi). It covers approximately 17% of Earth's surface an…
https://en.wikipedia.org/wiki/Atlantic_Ocean
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wikipedia NEUTRAL — The Atlantic cod (pl.: cod; Gadus morhua) is a fish of the family Gadidae, widely consumed by humans. It is also commercially known as cod or codling. In the western Atlantic Ocean, cod has a distribu…
https://en.wikipedia.org/wiki/Atlantic_cod
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wikipedia NEUTRAL — Atlantic herring (Clupea harengus) is a herring in the family Clupeidae. It is one of the most abundant fish species in the world. Atlantic herrings can be found on both sides of the northern Atlantic…
https://en.wikipedia.org/wiki/Atlantic_herring
+ 3 more evidence sources
info
“the ability to reproduce in waters where the salinity drops to as low as 2–3‰ compared with 34–35‰ in the ocean.”
SINGLE SOURCE
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web search NEUTRAL — The key is the ability to reproduce in waters where the salinity drops to as low as 2-3‰ compared with 34-35‰ in the ocean.
https://phys.org/news/2026-05-atlantic-herring-brackish-balt…
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web search NEUTRAL — The herring is one of few marine fishes that reproduce throughout the Baltic Sea where the salinity drops to 2-3‰ in the Bothnian Bay, compared with 35‰ in the Atlantic Ocean (Figure 1A).
https://pmc.ncbi.nlm.nih.gov/articles/PMC4854517/
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web search NEUTRAL — The Baltic Sea emerged after the last glaciation and has existed for only about 8,000 years. An early coloniser, the herring is one of the few Atlantic fishes that have successfully adapted to the low…
https://e3.eurekalert.org/news-releases/1127079
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“the researchers sequenced the whole genome of a large number of herring, Atlantic as well as Baltic”
SINGLE SOURCE
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web search NEUTRAL — Here, we use whole genome population sequencing of Atlantic and Baltic herring to reveal the underlying genetic architecture at an unprecedented detailed resolution for both adaptation to a new niche …
https://elifesciences.org/articles/12081
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web search NEUTRAL — In this new study, the researchers sequenced the whole genome of a large number of herring, Atlantic as well as Baltic, and show that genetic changes in genes expressed in sperm, eggs and early embryo…
https://phys.org/news/2026-05-atlantic-herring-brackish-balt…
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web search NEUTRAL — Now the scientists have sequenced entire genomes from groups of Atlantic and Baltic herring and revealed hundreds of sites that are associated with adaptation to the Baltic Sea.
https://thefishsite.com/articles/herring-genome-proides-insi…
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“A gene for an anion channel that is only expressed in sperm [was highlighted as particularly important].”
SINGLE SOURCE
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web search NEUTRAL — A gene for an anion channel that is only expressed in sperm. The researchers' hypothesis is that the altered protein sequence of this channel is required to maintain sperm function when spawning occur…
https://phys.org/news/2026-05-atlantic-herring-brackish-balt…
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web search NEUTRAL — Herring (Clupea harengus) can genetically adapt to their environment – for example how salty, dark or warm the water is where it lives. Leif Andersson heads a project aiming to explain the mechanisms …
https://kaw.wallenberg.org/en/research/revealing-herrings-ge…
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web search NEUTRAL — Genetic research on Baltic herring. As the climate crisis has worsened, the question of whether genetic modification or knowledge about species’ genetic adaptation can be used to protect or help speci…
https://balticwaters.org/en/deep-dive-genetic-adaptation-in-…
info
“The combined effect of genetic changes in one of the major egg envelope proteins and an enzyme that makes crosslinks between these envelope proteins results in a reinforced envelope that protects the eggs from swelling when exposed to brackish water.”
SINGLE SOURCE
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web search NEUTRAL — Genetic processes work in combination with an organism's environment and experiences to influence development and behavior, often referred to as nature versus nurture.
https://en.wikipedia.org/wiki/Genetics
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web search NEUTRAL — Apr 22, 2026 · Genetics may be defined as the study of gene s at all levels, including the ways in which they act in the cell and the ways in which they are transmitted from parents to offspring.
https://www.britannica.com/science/genetics
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web search NEUTRAL — Dec 8, 2025 · Genetics involves scientific studies of genes and their effects. Genes carry the instructions for making proteins, which direct the activities of cells and functions of the body. For exa…
https://researchbank.kaiserpermanente.org/what-is-genetics-w…
info
“the Baltic herring has 20 extra copies of a gene that degrades the egg envelope”
SINGLE SOURCE
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web search NEUTRAL — The reinforced egg envelope protects the embryo, but results in a challenge when the larvae are ready to hatch. However, thanks to strong natural selection, the Baltic herring has 20 extra copies of a…
https://phys.org/news/2026-05-atlantic-herring-brackish-balt…
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web search NEUTRAL — Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert syste…
https://www.eurekalert.org/multimedia/1130058
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web search NEUTRAL — Here, we use whole genome population sequencing of Atlantic and Baltic herring to reveal the underlying genetic architecture at an unprecedented detailed resolution for both adaptation to a new niche …
https://pmc.ncbi.nlm.nih.gov/articles/PMC4854517/
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“all herring spawning in the Baltic Sea, irrespective of specific geographic region, carry the genetic changes in these four genes.”
INSUFFICIENT EVIDENCE
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“The Baltic herring was classified as a subspecies of Atlantic herring by Linnaeus”
INSUFFICIENT EVIDENCE
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“Sperm, egg, and embryo proteins critical for genetic adaptation of herring to low salinity in the Baltic Sea, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2601861123.”
PENDING
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.