Squid populations have been climbing for decades while many fish stocks shrink, and a 2026 modelling study says the usual suspect, warming seas, is probably not the driver. The better explanation, according to the researchers, is that humans removed the big fish that eat squid.
The idea got a fresh airing on 23 October 2026, when security writer Bruce Schneier flagged it in his Friday Squid Blogging post. Here is what the research actually shows, and where it stops.
Key takeaways
- A 2016 study found cephalopod catch rates rose across 35 species or genera between 1953 and 2013.
- A preprint posted to bioRxiv on 1 September 2026 tested the causes with an ecosystem model.
- In the model, removing top predators raised squid numbers, while warming lowered them.
- The preprint is not peer reviewed, and the authors call the mechanisms unclear.
Are squid populations really increasing?
Yes, on the best long-term evidence we have. A 2016 paper in Current Biology, led by Zoë Doubleday at the University of Adelaide, analysed catch-rate data from 1953 to 2013 and found rising abundance across 35 cephalopod species or genera (ScienceDaily summary).
Catch rate means animals caught per unit of fishing effort. Crucially, the rise showed up even in surveys unrelated to fisheries, so it was not only a case of boats getting better at catching squid.
What did the 2026 study test?
Rémy Denéchère, a marine biologist at the Technical University of Denmark, and colleagues built a model called FEISTY-squid. It tracks five groups: small pelagic fish, large pelagic fish, bottom-dwelling fish, deep-water mesopelagic fish and squid. They ran it on a shallow shelf of about 50 metres and an open ocean about 2,000 metres deep, according to Ecoticias.
Then they poked the virtual ocean in two ways: remove the big predators, and warm the water by about 2°C.
What happened when predators disappeared?
Squid numbers rose in both systems. Fewer predators meant more small fish left for squid to eat, and squid can eat roughly 30% of their body weight a day, as ScienceAlert reported on 6 September 2026.
But squid did not simply take over. The lost predators carried far more biomass than squid gained, so the ecosystem ended up poorer overall. In the authors’ words, squid did not simply fill the void.
The model also showed squid eating each other more as predators declined, which put a brake on growth. Food supply, not being eaten, seemed to set the ceiling.
Do warmer oceans help squid?
In this model, no. Warming lowered squid biomass in both systems. Think of squid as a car with a thirsty engine: heat raises the fuel burn, and the fuel supply does not rise to match.
Squid populations: the three explanations compared
| Explanation | What the 2026 model found | Confidence |
|---|---|---|
| Predators overfished | Squid rise, but ecosystem loses far more biomass | Plausible, model only |
| Warmer seas | Squid biomass falls | Contradicts the popular theory |
| Fast life cycle | Squid grow up to five times faster than fish and live one to two years | Helps explain quick responses |
That last row matters. A short life lets squid exploit a disturbed ecosystem quickly. The authors suggest the boom reflects that opportunism more than any single cause.
How much should you trust this?
Treat it as a strong hint, not a verdict. The work is a preprint, so no outside reviewers have signed off yet. It is also a simulation, not a headcount of real squid.
The authors flag gaps: the model leaves out colder deep water and the effect of temperature on squid embryos, and existing data are too thin to predict how warming will play out. They call the proposed mechanisms speculative.
My opinion: the result is useful mostly because it breaks a lazy story. “Warming oceans, therefore more squid” is neat, and this model says it may be backwards.
What happens next
Expect the preprint to go through peer review, and expect other teams to test it against real catch and survey data from individual regions. The Humboldt squid, which has spread toward Chile and Alaska, is one obvious test case; Oceana notes that warming and the loss of competing predators may both have played a part there.
The model also hints at a twist. If predator stocks recover while oceans keep warming, squid biomass could eventually fall. That projection is speculative and depends on both trends continuing.
For more on how oceans respond to pressure, see our piece on the Baffin Bay ice shelf.
FAQ
Are squid populations growing everywhere?
Not necessarily. The 2016 analysis found a broad upward trend across many species, but regional patterns differ and the data are patchy.
Is a squid boom good news?
Not by itself. In the model, the ecosystem lost far more predator biomass than squid gained, so more squid signals a disturbed food web, not a healthier one.
Is the study peer reviewed?
No. It was posted to bioRxiv on 1 September 2026 as a preprint, and its conclusions could change.
Next step: read the ScienceAlert write-up linked above, then check back when the paper is peer reviewed to see whether the findings hold.
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