Ecocentric

Why Warming Oceans Could Mean Dwindling Fish

Scientists knew that climate change would eventually impact fisheries, but new research indicates that warming water is already affecting the kinds of fish that end up on your dinner table

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Jeff Rotman/Photolibrary/Getty Images

Fish catches could be hurt by climate change

It’s easy to forget that global warming doesn’t just refer to the rising temperature of the air. Climate change is having an enormous, if less understood, impact on the oceans, which already absorb far more carbon dioxide than the atmosphere. Like so much of what goes on in the vast depths that cover more than two-thirds of our planet’s surface, the effect of climate change on the oceans remains a black box, albeit one that scientists are working to illuminate.

Here’s one way: fisheries. Wild fish remain a major source of protein for humanity — as well as a major source of reality-TV shows — and for some coastal communities, fish mean even more. Scientists aren’t clear about what effect climate change, including the warming of the oceans, will have on wild fisheries. As Mark Payne of the National Institute of Aquatic Resources writes in a new piece in Nature, ocean researchers “tend to view climate change as a dark cloud on the horizon: potentially problematic in the future, but not of immediate concern” — especially compared with the much more pressing threat of simple overfishing.

But now a new study in Nature makes the case that climate change — including the warming of the oceans — is already having a direct impact on global fisheries. Researchers led by William Cheung at the University of British Columbia’s Fisheries Centre created a new model that took the known temperature preferences of different species of commercial fish and compared those figures with catch numbers from around the world. They found that species comfortable in warmer waters have been replacing fish that are more accustomed to cool temperatures. That means climate change is altering the makeup of fisheries around the world — and that could be particularly bad for the tropics, which may eventually become too hot for even for fish that tend to prefer it on the warmer side.

As Cheung’s co-author Daniel Pauly put it in a statement:

We’ve been talking about climate change as if it’s something that’s going to happen in the distant future — our study shows that it has been affecting our fisheries and oceans for decades. These global changes have implications for everyone in every part of the planet.

The study’s methodology is clever. Trying to estimate fish populations and distributions has always been a difficult and highly contentious process for the simple reason that there is so much ocean. You can use sonar estimates and trawl surveys — literally dredging the ocean — to try to get more precise samples, but that’s difficult and expensive. Another option is to use commercial-catch statistics, which are kept by nearly every country in the world but tend to lack the requisite rigor. Countries have all sorts of motivations to fudge their catch numbers — especially in an age when catch quotas are being implemented to limit overfishing — and fishermen logically go after commercially viable species over unpopular fish, which then further skews the data.

The Nature team got around this problem by developing a sort of “thermometer” for fish distribution, analyzing the mean temperature of the catch (MTC). For each species in their database, the researchers derived a characteristic temperature range — in short, how hot or cold the fish could stand — weighted by the amount of each species caught.

They applied their metric to nearly 1,000 species across 52 large marine ecosystems from 1970 to 2006, looking at how water temperature changed over that period. (Hint: it got warmer.) And they found what you might expect: as water temperatures increased, so did the MTC, meaning that warm-water-preferring species moved in and cold-water-preferring species moved out.

Because catch numbers do not automatically equal actual populations, we can’t say for sure that the changes Cheung and his colleagues saw are an absolute reflection of what’s happening to wild fish beneath the waves. Other factors — like consumer preferences or fuel costs — influence what kinds of species fishermen think are worth catching. But even the changes in the catch data alone are startling — especially for tropical regions, as Payne writes:

In these regions, the fact that the catch composition seems to have reached the terminal hot-water state means that further warming may reduce fishery yields, if it has not already done so. The countries that border tropical waters are also those that are the most dependent on fisheries as sources of employment, foreign revenue and food, and are least able to adapt to such changes.

The oceans can sometimes seem so vast that nothing we could do could possibly alter them. But climate change — and our enormous hunger for seafood — seems up to the task.

71 comments
BrianGreul
BrianGreul

What is having a direct impact on fisheries is not global warming... it's industrial fishing with "catch-it-all" nets and long lines.  The Japanese have systematically documented the decline of fisheries with their catch records.  Even now, Europe can't hold itself back from taking Yellowfin Tuna.  One way you can influence this is to stop buying unsustainable fish.  When you are in the market and at the restaurant, refrain from buying questionable fish.  Insist that you be served sustainable fisheries that are caught responsibly.

Pyotr Ilych Tchaikovsky
Pyotr Ilych Tchaikovsky

Oh.! I knew it...my intuition told me this Long time ago..."made in china" is not in anyway good for the planet's well being

gopvictory
gopvictory

Warming and cooling in the oceans has been going on for hundreds of thousands of years, climatologist are not going to tell you about that, nor about which waters are getting cooler. Data on collecting temperatures of the oceans has only been done for a hundred years.

Anthony Valenti
Anthony Valenti

Not to worry, our PM has assured us this is just the ramblings of mad scientists,. Go back to sleep Canada it will all be over in the morning .

culturewarnotes
culturewarnotes

Global Warming is as dangerous as fire-breathing unicorns.
The government should do something about both!

Bidemi Badmus
Bidemi Badmus

Lets all stick to the conventional 3Rs.....reduce, reuse, recycle

Fadi Adami
Fadi Adami

Human greed is responsible for the demise of this planet.

Debbie Matthews
Debbie Matthews

We have the ability to put a man on the moon..but refuse to do any thing about pollution that is killing life and eventually us

Ben Lindsey
Ben Lindsey

You're living in a delusional world Dwayne...

CrossWinds
CrossWinds

Revelation 16:3

Then the second angel poured out his bowl on the sea, and it became blood as of a dead man; and every living creature in the sea died.

Nick Beaty
Nick Beaty

I must admit, it does take a certain level of intelligence to fully understand Climate Change and all that encompasses. Included in the problem are the people who are so stubborn/ignorant to realize the impacts their lifestyles have on our earth, and who fail in understanding that our world is "round", those impacts stem much further than our back door! Pleases read "the Mystery of Easter Island" and tell me that humans can't have a negative impact on the ground in which they live, and then research the impacts our current social organization has on that very same earth!!

Dwayne Leon
Dwayne Leon

:/ does anyone read the Bible anymore?... because "climate change" effects aren't really all "they" make them out to be... this is no excuse for being irresponsible though, but seriously, people need to wake up from their slumber... we're living in perilous times...

KMcAndre
KMcAndre

I like the title...COULD mean fewer fish? Come on...aren't we beyond denying the obvious by now? This is real and it is going to bite our children's children.

Diogenes Montesa Baena
Diogenes Montesa Baena

We have to remember that even our most routine decisions impact on our world... Things like buying made in china stuff (exporting our pollution), lining up at the drive-thru (if you don't know why it's bad, then that's why we have a problem), walking past an obviously real panhandler, not using a refillable, etc. little things but collectively, significant actions. (If you didn't vote in the last election, any election, you list your right to comment on anything). The point us were not helpless... We're just lazy and stupid, waiting for apocalypse.

Lauren Dimery
Lauren Dimery

You should start thinking about world dilemmas because its ultimately going to effect that kid in your arms. Jeff Dray. Wake up.

Jeff Dray
Jeff Dray

It's not practical to think about world dilemmas when we can't even solve our own.

baxtress
baxtress

How ignorant can people be, it's not the warming oceans that are causing a decline in fish, it's the over fishing that is depleting our fish supply and it's Spain, Japan and China that a mostly to blame. Spain has consumed all it's tuna & is now coming into other countries waters to fish theirs. Face the truth & stop the netting.

TheCaz64
TheCaz64

I am appalled at the mismatch between the data and the title.  The data support the notion of over-fishing as a primary driver.  The observation that warm water fish are increasingly found further north is not causatively linked to 'fleeing' warmer waters.  Since most commercial fishing is done in cold waters, the warm water fish could simply be exploiting ever emptier ecosystems.   This is doomsday journalism and nothing more.

BabuG.Ranganathan
BabuG.Ranganathan

GLOBAL WARMING MAY NOT BE MAN MADE

Dr. Larry Vardiman (scientist and physicist) of the Institue for Creation Research says:

"One possible scenario may be found in a recent series of articles by Henrik Svensmark and Nigel Marsh, cosmic ray specialists from Denmark, who have shown an indirect connection between galactic cosmic ray (GCR) intensity and global temperature.7,8,9 They are studying the influence of the Sun on the flow of GCR to Earth. The Sun's changing sunspot activity influences the magnetosphere surrounding the Earth permitting more GCR to strike the Earth during high periods of activity.

When the Sun is active, the intensity of GCR striking the Earth is increased, causing more ionization in the atmosphere, creating more carbon-14, and possibly creating more cloud condensation nuclei (CCN). This increase in CCN, in turn, appears to create more low-level clouds which cool the Earth. When the Sun is quiet the GCR intensity striking the Earth is reduced, allowing the Earth to warm. Svensmark and Marsh have shown a striking statistical correlation between sunspot activity and global cooling and warming over the past 1000 years.

The recent rise in global temperature may partially be due to current low solar activity supplemented by a recent increase in carbon dioxide concentration measured at Mauna Loa. The connection which still needs further study is the production of CCN and clouds by GCR." 

There is a good deal of science showing that global warming is not mad made. Yes, we still should have pollution controls, as we already do, but not to the extreme because it will unnecessarily hurt business.

Visit my newest Internet site: THE SCIENCE SUPPORTING CREATION

Babu G. Ranganathan
B.A. Bible/Biology

Author of popular Internet article, TRADITIONAL DOCTRINE OF HELL EVOLVED FROM GREEK ROOTS

DavidNutzuki
DavidNutzuki

If Human CO2 really was the planet killer you think it is, why would the millions of good and honest people in the global scientific community not be acting like their kids were doomed to unstoppable warming along with ours?

You can't have a little climate crisis and if you really believe it is possible, nothing will change your mind.

DavidNutzuki
DavidNutzuki

The debate for CO2 mitigation is costly and science would end the debate IF they were crystal clear in their warnings instead of avoiding ever saying their crisis was eventual or inevitable or imminent or simply WILL happen like they CAN say asteroid hits are. They have NEVER said anything close to this so how close to the point of no return will the lab coat consultants take before they do! If they said a crisis was inevitable etc. then myself and the others in the former believer majority would bounce back in full support.

DavidNutzuki
DavidNutzuki

Melting by itself does not prove my SUV gas is now in control of climate variation instead of NATURE and the tropical fossils found under both polar caps proves this melting is nothing new. Deny that!

28 years of science saying only "maybe" proves it won't be a real crisis.

DavidNutzuki
DavidNutzuki

What the lazy copy and paste news editors won’t tell you;
Science only believes it is; "real and happening" and has never said in 28 years that it will be a real crisis, only might be as not one single IPCC warning wasn't swimming in “maybe” and “could be” as in; “Help my planet is on fire maybe? 28 years of maybe prove it won’t be a real crisis?
"Climate change is real and is happening and could cause a climate crisis." - Science
Never have they ever said their comet hit of a crisis was as real and as "inevitable" as they like to say comet hits are. It's been a 28 year old "maybe" crisis. When will they say it is eventual and WILL happen? When it's too late?
So science didn’t commit any hoax, it was believers, news editors and politicians that lied and said it WILL happen because science never did say it would, only could. Deny that.