What will extra cephalopods mean for marine ecosystems?

Octopus vulgaris resting on a reef. This mollusc can be found in the Mediterranean Sea and in the Atlantic Ocean Octopus vulgaris resting on a reef. This mollusc can be found in the Mediterranean Sea and in the Atlantic Ocean MattiaATH/Shutterstock
03 Jun
2016
A delicious opportunity or proof of human impact on the ocean? The news of booming cephalopods (octopuses, cuttlefish and squid) has already divided seafood lovers and environmentalists. Whatever your opinion, cephalopods appear to be thriving while other marine species flounder, raising questions about the state of underwater ecosystems

A recent study published in Current Biology shows that cephalopod numbers have increased over the last six decades. By analysing numbers of cephalopods caught as bycatch in fishing vessels, researcher Zoë Doubleday of the University of Adelaide’s Environmental Institute, observed population rises all over the world. ‘Cephalopods are notoriously variable, and population abundance can fluctuate wildly, both within and among species,’ she says. ‘The fact that we observed consistent, long-term increases in three diverse groups of cephalopods, which inhabit everything from rock pools to open oceans, is remarkable.’

oie 6froxBbBE57EOctopus numbers are on the increase (Image: Kerry L Werry)

Cephalopods are flexible, both physically and ecologically. They have rapid growth and relatively short lifespans, leading scientists to speculate that they can keep up with the changes to their environment, especially warming oceans. In fact, warmer waters are thought to accelerate their life cycles, so long as it does not surpass their tolerance and food is not limited. Cephalopods may also be less at risk from predators, thanks to the global depletion of fish stocks. ‘It is relatively well documented that many fish species have declined in abundance due to overfishing,’ they write, ‘and several regional studies have suggested that cephalopod populations have increased where local fish populations have declined.’

Because they occupy the middle of the food chain, a boom in cephalopods will undoubtedly have an impact on marine ecosystems. ‘All cephalopods are carnivores and they eat lots of different types of prey including fish, other molluscs, and crustaceans,’ says Doubleday, ‘so it may reduce those animals. However, they are also an important source of food for many animals including seals, whales, predatory fish and sharks, and seabirds.’ She is wary, however, that their increase will go unchallenged for long, ‘they are becoming an ever-more important component in global fisheries, and feature increasingly on menus, so we might eat them before they increase too much.’

Share this story...

Submit to FacebookSubmit to Google PlusSubmit to Twitter

Related items

Geographical Week

Get the best of Geographical delivered straight to your inbox every Friday.

Subscribe Today

EDUCATION PARTNERS

Aberystwyth UniversityUniversity of GreenwichThe University of Winchester

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • The Air That We Breathe
    Cities the world over are struggling to improve air quality as scandals surrounding diesel car emissions come to light and the huge health costs of po...
    National Clean Air Day
    For National Clean Air Day, Geographical brings together stories about air pollution and the kind of solutions needed to tackle it ...
    Diabetes: The World at Risk
    Diabetes is often thought of as a ‘western’ problem, one linked to the developed world’s overindulgence in fatty foods and chronic lack of physi...
    The Nuclear Power Struggle
    The UK appears to be embracing nuclear, a huge U-turn on government policy from just two years ago. Yet this seems to be going against the grain globa...
    REDD+ or Dead?
    The UN-backed REDD+ (Reducing Emissions from Deforestation and Forest Degradation) scheme, under which developing nations would be paid not to cut dow...

MORE DOSSIERS

NEVER MISS A STORY - follow Geographical

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Oceans

East African countries are sharing shipping data in order to…

Wildlife

How many elephants can you see? How many orang-utans are…

Climate

The ocean floor is being deformed under the weight of…

Climate

Progress on halting warming has not been great throughout 2017.…

Oceans

Coral bleaching is widespread around the globe and as it…

Climate

Wales is the second best recycler in the world

Climate

A series of worrying reports by the Global Carbon Project…

Wildlife

While it was the impact on civilian populations that generated…

Oceans

For Sylvia Earle there is one over-riding threat to humanity…

Geophoto

Iceland is a sparsely populated country with one of the…

Wildlife

Baltic seals and fish-eating bird populations are increasing and could…

Oceans

The UN has committed to completely stopping plastic waste from…

Wildlife

The world’s most endangered marine mammal has just been thrown…

Climate

Sixty-two of the natural World Heritage Sites are now at…

Oceans

In February 2015, maritime lawyer and cold water swimmer Lewis…

Climate

Water, water may be everywhere, but as Marco Magrini discovers,…

Energy

A deeper look at Scotland’s recent decision to ban the…

Climate

The discovery of increasing levels of ozone-depleting compounds being emitted…

Geophoto

November is a dark, quiet month, but it also marks…

Energy

Could human waste one day be fuelling our homes and…