Claim: Global Warming is Reducing Fish Numbers

Guest essay by Eric Worrall

According to climate models fish numbers dropped substantially between 1930 and 2010.

Climate Change Shrinks Many Fisheries Globally, Rutgers-Led Study Finds

Climate change has taken a toll on many of the world’s fisheries, and overfishing has magnified the problem, according to a Rutgers-led study in the journal Science today.

Ocean warming led to an estimated 4.1 percent drop in sustainable catches, on average, for many species of fish and shellfish from 1930 to 2010. In five regions of the world, including the East China Sea and North Sea, the estimated decline was 15 percent to 35 percent, the study says.

“We recommend that fisheries managers eliminate overfishing, rebuild fisheries and account for climate change in fisheries management decisions,” said Chris Free, who led the research while earning a doctorate at Rutgers and is now a post-doctoral scientist at the University of California, Santa Barbara. “Policymakers can prepare for regional disparities in fish catches by establishing trade agreements and partnerships to share seafood between winning and losing regions.

We were stunned to find that fisheries around the world have already responded to ocean warming,” said Malin Pinsky, study co-author and associate professor in Rutgers’ Department of Ecology, Evolution, and Natural Resources. “These aren’t hypothetical changes sometime in the future.”

The study reports that the effects of ocean warming have been negative for many species, but also finds that other species have benefited from warming waters.

“Fish populations can only tolerate so much warming, though,” said senior author Olaf Jensen, an associate professor in Rutgers’ Department of Marine and Coastal Sciences. “Many of the species that have benefited from warming so far are likely to start declining as temperatures continue to rise.

Read more:

The abstract of the study;

Impacts of historical warming on marine fisheries production

Christopher M. Free, James T. Thorson, Malin L. Pinsky, Kiva L. Oken, John Wiedenmann, Olaf P. Jensen

Science 01 Mar 2019:
Vol. 363, Issue 6430, pp. 979-983
DOI: 10.1126/science.aau1758

Climate change is altering habitats for marine fishes and invertebrates, but the net effect of these changes on potential food production is unknown. We used temperature-dependent population models to measure the influence of warming on the productivity of 235 populations of 124 species in 38 ecoregions. Some populations responded significantly positively (n = 9 populations) and others responded significantly negatively (n = 19 populations) to warming, with the direction and magnitude of the response explained by ecoregion, taxonomy, life history, and exploitation history. Hindcasts indicate that the maximum sustainable yield of the evaluated populations decreased by 4.1% from 1930 to 2010, with five ecoregions experiencing losses of 15 to 35%. Outcomes of fisheries management—including long-term food provisioning—will be improved by accounting for changing productivity in a warmer ocean.

Read more (paywalled):

I think it is remarkable how scientists can eliminate the uncertainty of sketchy historical data, and the complexities of international fisheries management, major wars, and geographic differences between regions by plugging a few numbers into a climate model.

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Jon Scott
February 28, 2019 10:19 pm

Lies damned lies and models! I am fascinated that the questions any normal checker of work presented for publication should ask are not allowed in Climate Alarm Fantasyland. How the dirty pursuit of money by any means now colours all outpourings of once august centres of learning.

Caligula Jones
Reply to  Jon Scott
March 1, 2019 6:15 am

Yeah, hard to square this:

“These aren’t hypothetical changes sometime in the future.”


“We used temperature-dependent population models to measure the influence of warming on the productivity of 235 populations of 124 species in 38 ecoregions.”

Seriously, do they even hear themselves? A MODEL’S OUTPUT IS THE VERY DEFINITION OF THE @#$%@#% WORD “HYTOTHETICAL”.

I wish these jerks would stop torturing the English language.

Caligula Jones
Reply to  Caligula Jones
March 1, 2019 6:17 am

Heh. Helps to spell correctly when accusing others of language abuse. “HYPOTHETICAL” for “HYTOTHETICAL”

Pillage Idiot
Reply to  Caligula Jones
March 1, 2019 7:25 am


You were right with the first spelling.

A “HYTOTHETICAL” is when you take a hypothetical to absurd new heights.

Surely, that is an apt description of their modeled output.

Caligula Jones
Reply to  Pillage Idiot
March 1, 2019 9:20 am


T’was a combination of:

1) my old eyes
2) multi-tasking
3) an overreliance on spllchek, which leads to…
4) proofreading skills rotting

I notice that WUWT no longer has spllchck…or is just something on my end?

Bryan A
Reply to  Pillage Idiot
March 1, 2019 12:11 pm

The major problem with this paper is that Chris Free is listed first so the remainder of the papers authors obviously worked for Free

Reply to  Caligula Jones
March 1, 2019 6:50 am

Any prediction of future changes is by definition hypothetical.

February 28, 2019 10:39 pm

We used temperature-dependent population models..

What the hell is that then? Still no empirical observations. This is simply computer simulation which is usually either fabricated or manipulated because it can be. It’s sad that future generations will be “learning” by such methods of scientology.

February 28, 2019 10:54 pm

It can’t be overfishing, must be climate change.

Ron Long
Reply to  Alex
March 1, 2019 2:17 am

Right Alex, and it must be Climate Change Religion, because it looks like they divined the answer.

Bryan A
Reply to  Ron Long
March 1, 2019 12:13 pm

The Models say so…so it is /sarc

Reply to  Alex
March 1, 2019 4:26 am

Around the philippines it is fishing with dynamite 🙂

Ron Long
Reply to  LdB
March 1, 2019 9:48 am

LdB, do you mean the famous “DuPont Spinner”?

Farmer Ch E retired
Reply to  Alex
March 1, 2019 5:50 am

Could it have anything to do with world population? 2 billion in 1930 growing to 6 billion in 2000. Or could it be because they are using climate models??

Bryan A
Reply to  Farmer Ch E retired
March 1, 2019 12:14 pm

They are using Fishy Models

Manfred Schropp
February 28, 2019 10:55 pm

Smells fishy to me!

Reply to  Manfred Schropp
March 1, 2019 1:09 am

The decline in fish stocks correlates to all the sewage we’ve dumped into the oceans.

Patrick MJD
Reply to  joe
March 1, 2019 1:15 am

Not many modern countries dump raw sewage into water ways without treatment.

Reply to  Patrick MJD
March 1, 2019 6:02 am

mmmm…. Montreal, Quebec has been getting several permits the last few years to dump huge volumes of raw sewage into the St Lawerence River, thanks to Climate Barbie, Canada’s Minister of Environment and Climate Change. And Victoria, BC has been dumping raw sewage into the Pacific Ocean like forever. They are just building their treatment plant and will be ready in the near future. And then there is the whole 3rd world, but they are not modern countries.

william matlack
Reply to  Earthling2
March 1, 2019 10:36 am

My local weekly newspaper The Essex Free Press , posted
a notice from Enbridge Gas Inc. that they have applied to the Ontario Energy Board to to raise its natural gas rates effective April 1 2019 to recover costs associated with the Federal GREENHOUSE GAS POLLUTION PRICING ACT. Apparently raw poop in the waterways is o.k. but co2 is not. Go figure.

Patrick MJD
Reply to  Earthling2
March 1, 2019 3:53 pm

I did say modern. Yes, applying for permits to pollute. Same thing used to happen in the Wairarapa in “Clean Green” New Zealand. The Masterton district council was fined by the Wellington Regional Council for not applying to the Environment Court for a permit to dump untreated sewage in to the local rivers.

Reply to  Patrick MJD
March 3, 2019 11:03 am

Except for both Vancouver and Victoria BC which are both “Green” cities.

Radical Rodent
Reply to  joe
March 1, 2019 4:13 am

Correlation, though, is not necessarily causation.

Tim Gorman
Reply to  Radical Rodent
March 1, 2019 5:24 am

The same applies for smaller fish catches and global warming. Correlation is not causation.

I can’t see where this study proves causation.

Reply to  joe
March 1, 2019 3:41 pm

Fish thrive on sewage.

February 28, 2019 11:16 pm

It sounds ‘science denial’ if I tell this is bullshit, but heck, this looks like bullshit and smells like bullshit.

Goes to the same broad category with

We aimed at compiling all long-term insect surveys conducted over the past 40 years that are available through global peer-reviewed literature databases. To that effect we performed a search on the online Web of Science database using the keywords [insect] AND [declin] AND [survey], which resulted in a total of 653 publications.

Right, if you search for declines, you will find declines. If you want to estimate trends, that’s not what you do. It is very easy to ‘find’ a decline if one expects a decline and primed so, starts planning a literature review. If one is ready to commit a scientific forgery, it becomes even easier. In the current political climate, papers claiming doomsday sell well.

Reply to  Hugs
March 1, 2019 1:35 am

Science isn’t about discovery these days. It is about creating a theory and going out to find evidence to “prove” it. Obviously nobody looks for data that might disprove it. There are no science credits there.

Otto Støver
February 28, 2019 11:33 pm

And in another study here i Norway, scientists say that the amount of cod has risen more than expected due to sensible management.
Is there no limit to all the havok that CO2 is supposed to create?

Coeur de Lion
Reply to  Otto Støver
March 1, 2019 12:51 am

Somewhere there’s a website with 800 plus scare stories of which the best is the increase in UFO sightings as aliens worry about what we are doing to the planet.

Patrick MJD
February 28, 2019 11:35 pm

Climate models now track fish stocks? WOW!

Nothing to do with over-fishing? Nah! CO2 and climate change.

Reply to  Patrick MJD
March 1, 2019 11:21 am

this is as solid science as tree ring data.

This just continues to convince me that there’s no such thing as a climate scientists; they’re all statisticians who bend the data (including altering the datasets) to ‘prove’ their silly hypotheses.

Joel O'Bryan
February 28, 2019 11:36 pm

I saw the “Perspective” story about this Fish research article on my Science Mag email feed earlier today.
(which I still get in my email even though I ended my AAAS membership last summer because of Science editorial blatant dishonesty.)

So I first went an read the Science mag Perspective abstract. Here it is:

Climate change impacts on fisheries
by Éva Plagányi
Science 01 Mar 2019:
Vol. 363, Issue 6430, pp. 930-931
DOI: 10.1126/science.aaw5824
“Food security, climate change, and their complex and uncertain interactions are a major challenge for societies and ecologies (1). Global assessments of predicted changes in crop yield under climate change, combined with international trade dynamics, suggest that disparities between nations in production and food availability will escalate (2). But climate change has already affected productivity. For example, weather-related factors caused declines in global maize and wheat production of 3.8% and 5.5%, respectively, between 1980 and 2008 (3). On page 979 of this issue, Free et al. (4) report a comprehensive analysis that indicates a 4.1% decline between 1930 and 2010 in the global productivity of marine fisheries , with some of the largest fish-producing ecoregions experiencing losses of up to 35%. Their spatial mapping can help to inform future planning and adaptation strategies.

So Eva (the Perspective article writer) wrote (in my bold), “For example, weather-related factors caused declines in global maize and wheat production of 3.8% and 5.5%, respectively, between 1980 and 2008.”

My BS detector pegged out on that statement. Given that human population between 1980 and 2008 increased by over 33% in those 28 years from 4.9 to 6.6 Billion, and yet here a claim that a major food crop, global wheat, production had fallen by over 5% in that time!!! I knew that was Total Bull shit from Science Mag.

After just a few search items, I verified that Global wheat acres under cultivation fell from 1980 at 590 million acres world-wide to under 540 million acres by 2008. But in that time, global wheat production rose from 420 million metric tonnes to over 660 million metric tonnes. An actual 55% increase.

So for Science Magazine editors to blatantly lie about a verifiable historical fact (global wheat production) in the Perspective article abstract on the accompanying Fish research article, I knew it was lies and deception … all the way down.
I read no further.

Science mag and its editors continue their Big Lie on Climate issues… and it’s lies all the way down. And they aren’t even trying to hide it.

Larry in Texad
Reply to  Joel O'Bryan
March 1, 2019 12:29 am

These pseudo-scientists are far too enthralled by numbskulls like the late Paul Ehrlich (and his intellectual godfather Thomas Malthus), neither of whom bothered to consider the possibility that innovations in the science of food crops (thanks to Nobel laureates like the late Norman Borlaug, God rest his soul), and improvements and adaptations in the fields of animal husbandry and resource management have been taking place in the world on a regular basis since even Malthus’s time. But ideology replaces both physical observation and common sense in the world of climate science.

Reply to  Larry in Texad
March 2, 2019 6:30 am

As far as I know Paul Erich is not yet “the late.” But the rest of your comment is spot on.

Papa J Picolino
Reply to  Joel O'Bryan
March 1, 2019 2:04 am

Maybe it is a per capita decline. Since the regions with the fastest growing population garnered the biggest drop in productivity, then they might have unintentionally dropped the per capita phrase.

Rich Davis
Reply to  Papa J Picolino
March 1, 2019 2:39 am

Yes, unintentionally. That’s the ticket. UNINTENTIONALLY.

Joel O’Bryan
Reply to  Papa J Picolino
March 1, 2019 7:36 am

She didn’t qualify it. She wrote “global wheat production decline”. And I even verfied wheat per capita went up. And she didn’t say from some contrived computer model “if all else had remained constant” as a result of higher temps.
In science, clear communication is vital for people to trust.
No one can trust Science Mag on anything climate related. You’re a fool if you do.

Reply to  Joel O’Bryan
March 1, 2019 7:57 am

The percent is just an imaginary modelled missing growth they rename as decline.

Bullshit (Frankfurt) again.

Caligula Jones
Reply to  Joel O'Bryan
March 1, 2019 6:23 am

Thanks for the work, that hit me too when I read it (and I continue to get those emails as well even though I’ve ended my support as well).

Would save a lot of money, though, if they took those supercomputers away from the chimpanzees and bought them dollar store Ouija boards.

Garland Lowe
March 1, 2019 12:25 am

Climate model data predicts the “scientist” using the models are clueless (90% confidence). Verified by observed data.

March 1, 2019 12:27 am

I refer you to this article published 27th Feb, on this site, titled ‘ Achieving Paris Climate Target could net additional billions in fisheries revenue’. Something fishy here!

March 1, 2019 1:49 am

If there were to b e a significant rise inn the temperature in the Northern Hemisphere say about 3 degrees Celsius, about the same as on the equator, then we humans would simply adopt. Same goes for all of the other specs of life. Fishes if a but warm would move to the North, problem solved.

Of course its overfishing, and as we in he West cannot dictate to the Asian parts of the World, it will continue.

But of course its far easier to blame it all on CO2 and the Climate Change mantra.


March 1, 2019 4:12 am

The brain GW of climate alarmists have clearly reached a catastrophic tipping point, inducing an irreversible cognitive disruption (known as Dory’s syndrome).

Tom in Florida
March 1, 2019 4:48 am

I have always wondered that if humans didn’t eat lobsters, would there now be so many that we could walk from New York to London?

March 1, 2019 5:23 am

I’m no expert but I’ve lived on or along the ocean for 40 years and the change in the scale of fishing is astonishing . From mom and pop fishing boats to huge industrial scale Chinese fishing factories Harvesting fish species worldwide .The fish harvest that we know about just from US fisheries has increased exponentially .

March 1, 2019 5:35 am

“Global Warming is Reducing Fish Numbers [..] According to climate models fish numbers dropped substantially between 1930 and 2010.”.

That is an incredibly stupid statement. If you wanted to know about fish numbers, how dumb would you have to be to use a climate model. How much dumber would you have to be to believe the climate model and not check the numbers against some other source of information – like data on fish, for example. From 1950 to 1990, the global fish catch quadrupled ( ). Since then, the catch has been steady. Only a climate model with its eyes shut and ears blocked could think that the reason was global warming:
The reason why fish catches have remained fairly stable is because over time the coastal maritime regions were fished out, prompting the fisheries to spread out into new areas. They have expanded in geographical terms, from the traditional fishing grounds of the North Atlantic and North Pacific further and further south. They have also penetrated into ever-deeper waters. Only a few decades ago it was virtually impossible in technical terms to drop nets deeper than 500 metres. Today the fisheries are operating at depths of up to 2000 metres. Moreover, once the stocks of the traditional species had been exhausted, the fishing industry turned to other species.“.

March 1, 2019 7:27 am

Back in my territory. This paper is truly fantasyland. The authors obviously do not understand the landings data or how such are derived. The idea that any fisheries landing data is close enough to reality that they came predict declines due to temperatures is just stupid no matter how wonderful they think their models are. Those of us in the business of fisheries management spent much of our careers trying to improve the data quality and quantity. Even up until the 1980s we weren’t even close for many species. A lot of effort and money went into improving just landings data.

I worked on a species where we had a large percentage of the landings. We knew almost every boat in the fishery. We even had individual sizes and for a larger percentage we had sex. NMFS and ICCAT at the time agreed officially, on the record, it was the best and most complete data set for any species in the Atlantic Ocean probably the world.

Meanwhile, Brazil, a major player punished a scientist who had recorded the landings, individual size and sex of every single billfish and tuna landed at one port in Brazil. Why was he punished? because his data did not agree with the official record provided to ICCAT, his data show landings just in the one port exceeded the official record for total country landings.

There are very few species that have any landings data prior to WWII. North Sea Herring records were possibly in the ballpark but the species was overfished by the 1970s, collapsed a while later, and is finally coming back.

The single biggest problem with fisheries today is overfishing both legal and illegal. Legal supposedly well managed fisheries still are overfished. Illegal, pirate fishing is a larger percentage of the world’s catch than most people imagine. Of course the pirates keep detailed records and report them regularly to fishery management organization, NOT.

Pollution wise it is not so much the nutrients from human bodily waste but the other pollutants both in the sewage and from industrial outfalls. Just as the China and SE Asia that done little about air pollution neither have they done much about water pollution. Industrial chemicals can impact the fisheries in relatively large coastal areas.

Joshua Combs
March 1, 2019 7:55 am

I’m not completely sure why a trade agreement is a solution to this problem. If fisheries are hypothetically being decreased by climate change, than a trade agreement isn’t going to solve that problem. I suppose if climate change was totally regional, than maybe, but I don’t see that conclusion in the paper.

HD Hoese
March 1, 2019 8:02 am

Fisheries models have the same problem as climate models, separating natural fluctuations like temperature from human predation. This sometimes stacks hypotheses because the fishing stock analysis can be dependent on the climate analysis.

There has also been the tightened, sometimes needed, sometimes political, regulations, especially in
developed countries. In Texas they successfully manage for big fish, check the sports fishing magazines. In Scotland and France managers went as far as breaking up and burning old antique wooden fishing boats to keep them from returning to the fishery. (Lockley, P. 2000. Decommissioning–a failed policy. Maritime Life and Traditions. 7:2-15.). Some claims of overfishing were clearly erroneous.

Fish populations fluctuating with temperature is a long known event easily confused and sometimes difficult to separate from heavy fishing pressure. Nearly all species of fished stocks produce trillions and trillions of eggs, making predictions difficult and natural fluctuations sometimes enormous. Papers go back at least to the 1930s, records in Europe centuries.

Dr. Deanster
Reply to  HD Hoese
March 1, 2019 8:33 am

The variation in temperature with depth that fish experience is an order of magnitude greater than ocean warming. ….. more rubbish by the brain dead Alarmists who lack critical thinking skills.

Dr. Deanster
March 1, 2019 8:31 am

So … we are over fishing certain areas (in particular China, with 1.5 Billion mouths to feed) …. but these idiots have to throw in “Global Warming” as part of the cause. What a crock.

Bruce Ranta
March 1, 2019 8:58 am

Model Schmodel.

March 1, 2019 11:19 am

Just how does a model explain fish populations over the last 89 years?

It can’t.

March 1, 2019 1:22 pm

When they can show me the temperature range for feeding and breeding by all 124 species they studied I might believe some of their “data”. Temperature increase has been minor in the oceans, and most fish move either horizontally or vertically to find comfortable/functional conditions. Show me your biological data. Whatever assumptions you put into the computer are meaningless without observations. The oceans are being harvested chaotically, with many countries totally ignoring any attempt at regulation/management.

March 1, 2019 2:48 pm

Compare the model simulated fish population of less than a century to a Global Study based on core samples that counted historical fish population cycles, by counting fish scales in sedimentary layers. These empirical records go back hundreds and thousands of years.

Not surprisingly fish populations trend with Global DT and ocean cycles like PDO. The data also shows correlation with LIA, MWP, Roman and Minoan warm periods… More Data Mann forgot to “Get Rid of”.

March 1, 2019 3:44 pm

How much have the SST increased? <1°C? I don't think that will have any effect on fish.

Reply to  Jeff in Calgary
March 1, 2019 4:14 pm

All good fisherman know, when it is cool in the morning, the fish are shallow. As it gets warmer, the fish simply go deeper…… D’OH !

Derek Colman
March 1, 2019 5:20 pm

I suppose it couldn’t have anything to do with the fact that there are now twice as many people eating fish as there were in 1930.

Reply to  Derek Colman
March 1, 2019 7:04 pm

But kowtowing to the Paris agreement is a fish aphrodisiac.

March 1, 2019 8:03 pm

Overfishing is causing a reduction in fish numbers. But that doesn’t fit the narrative now, does it?

March 2, 2019 10:06 am

These is no science more “unsettled” than fisheries. You can go to Woods Hole, with more specialists in Marine Science than any spot on the planet, and find no one has much confidence in predicting next years population of even the local fish. I can’t think of a computer model less likely to succeed.

Luc VC
March 3, 2019 4:19 am

They eliminate the over fishing by studying protected fishing grounds (with quota). The data was always going to be too sparse to draw a meaningful conclusion. However they totally overlooked sport fishing which is not accounted for in non US fishing grounds. For the EU sport fishing exceeds the 4%. Meaning warmer water is good for fish according to their own study after correcting for sport fishing.

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