Squid Are Taking Over the Ocean—Kinda

Research and Further Reading:

• New squid biomass study by Rémy Denéchère and colleagues (2026 preprint) — This research has not yet been peer-reviewed.

  
  

• Global Proliferation of Cephalopods (Current Biology, 2016)

  
  

• Squid Biology and Feeding Facts—Australian Antarctic Program

  
  

• Squid Are Taking Over the Ocean—but Not for the Reason You Might Think—ScienceAlert

Humans have spent the past century overfishing marine predators, disturbing the seafloor, and steadily warming the ocean, and squid appear to have looked at the resulting chaos and said, “Finally, some room to grow.” Across many parts of the world, these tentacled opportunists have become increasingly abundant while numerous fish populations have declined or moved into new habitats. That does not mean the oceans are about to become one giant calamari convention, but the pattern has been large enough to catch scientists’ attention. In a landmark 2016 study published in Current Biology, researchers examined six decades of data and found that populations of cephalopods—including squid, octopuses, and cuttlefish—had increased globally. The increases appeared in species living near the seafloor and in the open ocean, and they occurred both in heavily fished populations and in populations that were not targeted by commercial fisheries. This suggested that fishing alone could not explain what scientists were seeing. Something about the rapidly changing ocean seemed to be giving these flexible, fast-growing animals an advantage.

One popular explanation was that overfishing had removed many of the large fish that normally eat squid. If fewer predators were around, squid populations could increase with less chance of becoming somebody else’s lunch, which sounds like a straightforward case of ecological cause and effect. Scientists also suspected that rising ocean temperatures might accelerate squid growth because squid are cold-blooded animals whose development and metabolism are strongly influenced by water temperature. However, a new study led by marine biologist Rémy Denéchère suggests that the real explanation may be more complicated. The researchers used computer models to simulate marine food webs and investigate how squid and fish might respond to the loss of top predators and changes in water temperature. When large predatory fish were heavily fished in the models, squid biomass increased, but the increase was relatively small compared with the enormous decline in predatory fish. In other words, squid did not simply move into the space left behind and replace everything humans had removed.

The models suggest that squid may benefit from predator removal in a more indirect way. Large predatory fish do not eat only squid; they also consume many of the smaller fish that squid eat. When those predators disappear, more small fish may remain available for hungry squid, creating a conveniently stocked seafood buffet. Squid need that food because they live extremely active lives and can consume an astonishing amount in a short time. According to the Australian Antarctic Program, some squid can routinely eat 30 percent or more of their body weight in a single day. For a 150-pound human, that would be like eating at least 45 pounds of food every day and insisting it was necessary because you have a fast metabolism. This enormous appetite helps squid grow rapidly, but it also means their success depends heavily on whether enough prey is available.

The study’s biggest surprise involved temperature. Rather than producing a massive squid boom, warmer water actually reduced squid biomass in the researchers’ models. Higher temperatures can increase a squid’s metabolism, causing it to use more energy for movement, growth, and basic survival. If the amount of available food does not increase at the same time, a warmer squid may burn through its energy faster than it can replace it. It is essentially doing high-intensity cardio in an ocean where the refrigerator is empty. Real marine ecosystems are more complicated than any computer model, however, and factors such as water depth, seasonal changes, local prey populations, and the effects of temperature on squid embryos could alter the outcome. The new research is also currently a preprint, meaning it has been made publicly available but has not yet completed formal peer review.

If warming and predator loss do not completely explain the historical rise of squid, their success may come down to one of their greatest abilities: responding quickly to environmental disturbance. Many squid grow much faster than fish, reproduce rapidly, and live for only one or two years. That live-fast, reproduce-fast, die-young lifestyle allows an entire squid population to react to changing conditions within a relatively short period. When fishing, marine heat waves, or shifting currents reorganize an ecosystem, squid may be among the first animals capable of exploiting newly available food and habitat. Researchers sometimes describe squid as “first invaders” because they can quickly enter and use resources in disturbed environments. They are not necessarily conquering healthy ecosystems through superior tentacle power; they may simply be especially good at finding opportunities after an ecosystem has been disrupted. In that sense, the squid boom may tell us as much about the declining stability of the ocean as it does about the impressive adaptability of squid.

That adaptability should not be mistaken for invincibility. If squid populations are ultimately limited by food, increasingly warm and depleted oceans could eventually work against them. Past environmental events off Southern California have shown that reductions in food availability can override the faster growth sometimes associated with warmer conditions. Squid may grow rapidly when temperatures rise, but only if they can find enough prey to support their greater energy demands. Scientists still do not have enough detailed information to predict exactly how different squid species will respond as warming, fishing, and food-web disruption continue. What is clear is that squid cannot perfectly replace the large predatory fish disappearing from marine ecosystems, and their expansion does not mean the ocean is recovering. Squid may be thriving because they are among nature’s best ecological opportunists—but even the ocean’s tentacled chaos noodles cannot flourish forever in a world without enough food.