Wednesday, May 25, 2016

Squids and octopuses — the ‘weeds of the sea’ — are on the rise

(The National Aquarium of New Zealand via AP)

From The Washington Post by Rachel Feltman

I for one welcome our cephalopod overlords.
The number of cephalopods — squid, octopus and other squishy sea aliens — has shot up over the past six decades, even as humanity's influence on the ocean (read: climate change, pollution and overfishing) has caused many marine populations to plummet, according to a study published Monday in Current Biology.

 Japan: Giant deep sea squid swims in bay

In other words, the ocean is becoming a more difficult place to live — and all of that empty space means everything is coming up octopus.
"Cephalopods are often called 'weeds of the sea' as they have a unique set of biological traits, including rapid growth, short lifespans and flexible development," study author Zoë Doubleday of the University of Adelaide said in a statement.
"These allow them to adapt to changing environmental conditions (such as temperature) more quickly than many other marine species, which suggests that they may be benefiting from a changing ocean environment."

The researchers analyzed the rate at which cephalopods have shown up in fishing catches or sampling efforts from 1953 to 2013.
The study included 35 cephalopod species or genera representing six families.
As a whole, they found that the group was thriving and becoming more prolific.

Giant Australian cuttlefish in Spencer Gulf, South Australia. (Scott Portelli)

Doubleday didn't set out trying to show that these populations were booming.
In fact, she and her colleagues were troubled by the apparent decline of the giant Australian cuttlefish.
Luckily, it looks as if things are on the up-and-up for that population as well.
"To determine if similar patterns were occurring elsewhere, we compiled this global-scale database," she explained. "Surprisingly, analyses revealed that cephalopods, as a whole, are in fact increasing; and since this study, cuttlefish numbers from this iconic population near Whyalla are luckily bouncing back."

But while that's great news for the giant Australian cuttlefish, scientists aren't so sure how to feel about an ocean where squid, cuttlefish and other octopods are all on the rise.
“I guess if you're a squid or octopus fisherman, these increases may seem like a great thing,” Benjamin Halpern from the University of California, who wasn't involved in the study, told the Atlantic magazine.
“But such dramatic global changes are quite worrisome. When we change the oceans this much, we move things into a new state — one that we know much less about. We might have more squid on our plates in the short run. What are we risking losing in the long run?”

The point is that we don't really know how an influx of these voracious predators will change the ocean — and that's a little scary.
So should we prepare for a future with a lot more tentacles?
That's unlikely.
Cephalopods may be super versatile, but their population booms are expected to rise and fall in a pretty self-regulating fashion — as was the case with the giant Australian cuttlefish.
In fact, the researchers don't think cephalopods are necessarily safe from the same overfishing that's helped them prosper.
It "will be critical to manage cephalopod stocks appropriately so they do not face the same fate as many of their longer-lived counterparts," they write in the study.

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