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Study

Marine fish may be biochemically constrained from inhabiting the deepest ocean depths

Yancey, Paul H.; Gerringer, Mackenzie E.; Drazen, Jeffrey C.; Rowden, Ashley A.; Jamieson, Alan

Proceedings of the National Academy of Sciences, 2014

Peer-reviewedcomparative studywild

What they did

Measured concentrations of the protein-stabilising molecule trimethylamine N-oxide in fish across a wide depth range, and extrapolated the relationship to find the depth at which the required concentration would make a fish osmotically unviable.

Studied in
Actinopterygii
Sample size
fish sampled across a depth gradient into the hadal zone

What they found

TMAO concentration rises linearly with depth, and extrapolation gives a limit of roughly 8,200 metres, beyond which a fish would be osmotically hyperosmotic to seawater. No fish has been reliably recorded below approximately that depth, though the trenches extend far deeper.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The absence of fish in the deepest trenches is explained by a biochemical constraint rather than by food, temperature or sampling failure.

How NatureHQ reads it

A rare and satisfying result: a limit derived from chemistry, published as a prediction, and matched by where the animals actually stop. NatureHQ presents it as one of the clearest cases of a physiological ceiling that can be calculated rather than merely observed.

Limitations

  • The limit is an extrapolation from a measured trend, and other constraints could coincide with it.
  • Sampling the hadal zone is difficult, and absence of records is weaker evidence than presence.

The experiment, explained

  • A limit calculated before it was confirmed

    Trenches go to nearly 11,000 metres and fish are not found in the deepest parts. Is that a sampling failure, or a real limit?

What this study is used for on NatureHQ

One study can inform several subjects. Here is everywhere this one is cited.

Finding the paper

Published by: Proceedings of the National Academy of SciencesPublished in PNAS.

doi.org/10.1073/pnas.1322003111

Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.

NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-03.