FEATURE - Man's environmental mistakes may fuel squid boom
Author: Michael Christie
Some squid experts believe the speedy cephalopods are swiftly filling the gaps left by overfishing of their predators and competitors such as tuna and cod, changing the ecosystem of the earth's oceans in ways not yet fully understood.
Evidence also suggests that warmer sea temperatures caused by climate change could speed the squid's conquest of the waters, boosting its reproductivity, growth and numbers.
"It's kind of hard to really nail down but anecdotally it looks like something is going on with these squid populations," said George Jackson of the Institute of Antarctic and Southern Ocean Studies in Australia's island state of Tasmania.
"There are places like the Gulf of Thailand where there's a lot of squid now but not a lot of fish," the University of Tasmania squid specialist told Reuters.
Not everyone agrees, and Jackson's hypothesis has already caused a stir in the small global community of squid researchers.
Little is known about the cigar-shaped swimmers which range from the giant 250 kg (550 pound) Architeuthis with its 18-metre arms to the diminutive 20-to 50-cm (6-to 20-inch) North American Lologi pealei.
But one thing quickly apparent to any researcher vainly trying to rear a squid in a laboratory is that they are extremely sensitive to changes in their environment, leading New Zealand squid expert Steve O'Shea said.
Rather than giving the squid an opportunity to fill a vacuum, overfishing could just as easily lead to a complete ecosystem collapse and extinction for some types of squid, which have been known to jet along at up to 20 knots (23 mph).
"I don't want to predict which way it's going to go, up, down. It definitely could go either way," said O'Shea, who works at the NZ National Institute of Water and Atmospheric Research.
Nor is there a definitive way to put an actual number on the world's squid population. But it is possible their biomass may have already surpassed the whole of humanity.
Every year sperm whales are believed to eat the equivalent in squid of half the body weight of all the earth's people.
Data shows the international tuna catch has jumped to four million tonnes a year from two million tonnes before 1994.
That could mean 20 million tonnes of squid may have escaped being eaten by the extra two million tonnes of tuna the world's fishermen are hauling onto kitchen tables each year.
If Jackson is right, a possible increase in the numbers of squid could also be accelerated by warming sea temperatures that some scientists blame on man-induced climate change.
Scientific data shows squids grow faster when temperatures rise by one or two degrees Celsius because of their protein-based metabolism which converts food into growth rather than into fat.
Growing faster means they mature quicker and reproduce earlier.
"If you warm them up a little, you just snowball them even faster," said Jackson.
"You may not get a population explosion but a rapid increase in growth, meaning that those populations are going to be turning over faster and there's going to be a bigger biomass presumably."
FOOD AND CURRENTS
The caveat is food and underwater currents.
Jackson said his own studies into the El Nino weather pattern impact on squid populations off California found that the warmer waters produced by the phenomenon reduced upwellings and food supplies, and squid populations actually declined.
When the last El Nino faded in 1998 and its opposite, La Nina, turned the waters cool again, the squids recovered.
The reverse could easily apply to the seas around Australia and elsewhere where food always appears to be plentiful.
A new El Nino, the name given to a periodic warming of the Pacific which tends to trigger drought in eastern Australia but extra rainfall in western Latin America, is forming this year, giving Jackson another opportunity to study its effect.
Ultimately, Jackson is the first to concede that a hypothesis i