Octopus, squid and cuttlefish bounce back

Global warming and overfishing are thought to be behind a bounce back in octopus, squid and cuttlefish populations worldwide, new research reveals.

The "voracious predators" are considered the weeds of the sea because of their rapid growth, flexibility and short life expectancy, University of Adelaide study author Zoe Doubleday says.

"This allows them to adapt to changes in environmental conditions, such as temperature, faster than other marine species," she said on Tuesday.

The study showed that 35 species, collectively known as cephalopods, had been on the rise since the 1950s.

But in South Australia's Spencer Gulf, the numbers of cuttlefish were recovering after a steep decline in recent years.

The increase in cephalopods had a complex but significant impact on ocean food chains.

Project leader Bronwyn Gillanders said scientists were looking to additional factors to explain the population boom.

"It's hard but it's an important question to be solved as it can reveal to us a much larger story about how human activities are changing the oceans," she said.