Claim: Coral reef cover, biodiversity, fish catches have declined by half since the 1950s

Peer-Reviewed Publication



Coral reefs around the world are under threat because of climate change, overfishing, pollution, and more. Now, researchers reporting in the journal One Earth on September 17 offer the first comprehensive global look at what these impacts on coral reefs mean for ecosystem services, the ability of the reef to provide essential benefits and services to humans. Overall, the findings show that the significant loss in coral reef coverage has led to an equally significant loss in the ability of the reef to provide basic services, including food and livelihoods.

“Coral reefs are known to be important habitats for biodiversity and are particularly sensitive to climate change, as marine heat waves can cause bleaching events,” said Tyler Eddy (@tyzissou), a research scientist at the Fisheries & Marine Institute, Memorial University of Newfoundland who was a postdoctoral fellow at the University of British Columbia’s Institute for the Oceans & Fisheries when he started this research. “Coral reefs provide important ecosystem services to humans, through fisheries, economic opportunities, and protection from storms.”

In the new study, Eddy and colleagues conducted a global analysis of trends in coral reefs and associated ecosystem services including the following:

  • Living coral cover
  • Associated fisheries catches and effort
  • Differences fishing across the food-web
  • Coral reef associated biodiversity
  • Seafood consumption by coastal Indigenous peoples.

To explore these various aspects of the reef ecosystem, they combined datasets from coral reef surveys, estimated coral-reef-associated biodiversity, fishery catches and effort, fishery impacts on food web structure, and Indigenous consumption of coral-reef-associated fish to analyze global and country level trends in ecosystem services.

After putting it all together, the data show that the global coverage of living corals has declined by about half since the 1950s. So, too, has the capacity of coral reefs to provide ecosystem services. They find that the catches of fishes on the coral reef reached its peak nearly two decades ago and has been in decline ever since despite an increase in fishing effort. The catch per unit effort (CPUE), often used as an indication of changes in biomass, is now 60% lower than it was in 1950.

“Our analysis indicates that the capacity of coral reefs to provide ecosystem services has declined by about half globally,” said William Cheung, Professor at the UBC Institute for the Oceans and Fisheries and senior author of this study. “This study speaks to the importance of how we manage coral reefs not only at regional scales, but also at the global scale, and the livelihoods of communities that rely on them.”

The researchers also found that diversity of species on the reef has declined by more than 60%.

The findings lead the researchers to conclude that continued degradation of the reef in years to come now threaten the well-being and sustainable development of human communities on the coast that depend on the coral reef. “The effects of degraded and declining coral reefs are already evident through impacts on subsistence and commercial fisheries and tourism in Indonesia, the Caribbean, and South Pacific, even when marine protected areas are present, as they do not provide protection from climate change and may suffer from lack of enforcement and marine protected area staff capacity,” the researchers write.

“Fish and fisheries provide essential micronutrients in coastal developing regions with few alternative sources of nutrition” they write. “Coral reef biodiversity and fisheries take on added importance for Indigenous communities, small island developing states, and coastal populations where they may be essential to traditions and cultural practices. The reduced capacity of coral reefs to provide ecosystem services undermines the well-being of millions of people with historical and continuing relationships with coral reef ecosystems.”


This work was supported by the Nippon Foundation to the Nereus Program and the Ocean Nexus Center.

One Earth, Eddy et al.: “Global decline in capacity of coral reefs to provide ecosystem services” 

One Earth (@OneEarth_CP), published by Cell Press, is a monthly journal that features papers from the fields of natural, social, and applied sciences. One Earth is the home for high-quality research that seeks to understand and address today’s environmental grand challenges, publishing across the spectrum of environmental change and sustainability science. A sister journal to Cell, Chem, and Joule, One Earth aspires to break down barriers between disciplines and stimulate the cross-pollination of ideas with a platform that unites communities, fosters dialogue, and encourages transformative research. Visit To receive Cell Press media alerts, contact


One Earth




Global decline in capacity of coral reefs to provide ecosystem services



From EurekAlert!

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September 18, 2021 10:17 pm

From the paper –

“There were only a few observations in the early part of the time series, which originated from the western Indian Ocean, indicating high uncertainty around what the average coral cover was during the mid-20th century. The effects of climate change worldwide started prior to this period, suggesting that the historical baseline could have been higher (Figures S1 and S2).”

It is wore than we thought. Although strangely Australia does not rate a mention.
Although species richness is excellent.
GBR rates a mention because bleaching events are apparently new.

Last edited 1 year ago by lee
Joao Martins
Reply to  lee
September 19, 2021 3:15 am

The paper is absolutetely stupid, biased, subjective: just look at their Fig. 1A and check where, and how (with how much observations; that thei confess are mainly from the western Indic Ocean), they have established their “baseline”.

Simplistically, and having in mind the limitations that they confess, my first idea would be to discard all those “observations” before 1970 (only TWO, close to 1957 or 1958!) and establish a “baseline” with the more numerous and geographically wide(er)spread values of a decade centered, say, in 1970. BUT…

… but, in so doing, the conclusion would be that the corals are very well, thank you!…

Last edited 1 year ago by Joao Martins
Mark Kaiser
Reply to  Joao Martins
September 19, 2021 10:05 am

Good point on the “baseline” Joao

I’ll go you one further. If they had only gone back to 1968 they could have used a much higher baseline. See that little blue dot there at 95%? That’s a definitive whole “baseline”. Is it not?

Then the whole map of the world could have been bright scary red. (Figure 1B)

September 18, 2021 10:32 pm

“The effects of degraded and declining coral reefs are already evident through impacts on subsistence and commercial fisheries and tourism in Indonesia, the Caribbean, and South Pacific, even when marine protected areas are present, as they do not provide protection from climate change and may suffer from lack of enforcement and marine protected area staff capacity,”

Err, yes almost all the above is true except the digression into climate change.

Near shore coral reefs suffer the tragedy of the commons.
If I leave that cockle or mussel on the reef my neighbour will collect it and he or she and their family will get that extra bit of food rather than me and my family.

If we all cooperate and safeguard the reef my neighbour and I and our families can all make a better living by showing it off to rich city tourists but to do that we need organization and discipline.

Joao Martins
Reply to  GregK
September 19, 2021 3:24 am

Not exactly. Most figures in that article point to a change close to year 2000. Several metrics do. So, one should ask: what happened socially, politically, all over the world in the last years of the 20th century and early years of the 21st?

But, wait…

I just have written “all over the world”. But NO, this is wrong! Just check their maps in Fig. 1B, 3C-D and 5, the ones that relate more wiyh economy, and see that what the authors are trying to generalize to the whole world is but a phenomenon occurring in a few countries with similar economic situation and evolution!

Very good, in what concerns scientific rigour and/or honesty…

Rory Forbes
September 18, 2021 10:40 pm

Everything they “discovered” can easily be explained by poor management and over fishing. There is no evidence that “climate change” had the slightest thing to do with it. What tiny amount some climates have changed started a century and a half ago. Many climates haven’t undergone any noticeable change for centuries or even millennia.

Reply to  Rory Forbes
September 19, 2021 6:56 am

Yes, it is clear that they do not want to consider the bad fishing and fish collecting practices that depopulate or even destroy reef systems and only mention increased fishing effort as an indication of climate change.

A completely myopic and biased study.

Rory Forbes
Reply to  Charles Higley
September 19, 2021 9:28 am

It’s the fault of the universities who rely on government funding. Either the funding comes with strings attached or they’re virtue signalling with copious quantities of “climate change” garbage to attract all they can get.

Mark Kaiser
Reply to  Rory Forbes
September 19, 2021 9:57 am

Agreed Rory Forbes. Look no further than the collapse of the Grand Banks cod stocks off Newfoundland, CA. Happened in the late 70s early 80s. Nothing to do with climate and everything to do with over-fishing.

Rory Forbes
Reply to  Mark Kaiser
September 19, 2021 10:39 am

I remember the Grand Banks collapse very well … and the exact reason why it happened. From being the greatest fishery on the planet to zilch in almost the time it took to build the second wave of massive, ocean going trawlers twice the size of the first. Newfoundland went from a province of poor fishermen, with a single, self owned small boat, with a bunch of dories to a province of a few “wealthy fishermen” operating a syndicate owned ocean trawler owned by the bank.

We’re having the same problem here on the Northwest Coast of Canada with our salmon and herring stocks. Like with the Grand Banks, we had a “buy back” program to buy the licenses of all the small family run operators … mostly trollers and gill netters, and resell them to seiners on a tonnage basis. Beach five – ten small boats and use the license to build a humongous seine boat that can snare almost an entire run in one catch. The license market was a huge and prices skyrocketed. The touble was once the family sold their license (many native families relied on fishing) for a fortune, there ended the family income.

Last edited 1 year ago by Rory Forbes
Reply to  Rory Forbes
September 19, 2021 10:16 am

Climate change happens in the atmosphere. Fishing does not.

Rory Forbes
Reply to  Doonman
September 19, 2021 10:43 am

I’m guessing you had some sort of point in mind. Why ever didn’t you make a stab at offering it.

Hint: In a water planet like ours, the atmosphere is difficult to separate from the oceans.

Alan the Brit
Reply to  Doonman
September 20, 2021 12:18 am

Ok Bucko, as your mate Griff hasn’t had the decency to reply to my question, perhaps you can have the decency, so, please tell me, based on your vast knowledge of the Earth’s climate, when in the last four & a half billion years has the Earth’s climate ever stayed the same???

September 18, 2021 10:42 pm

One Earth publishes significant original research that seeks to understand and address today’s environmental grand challenges. The journal publishes across the full spectrum of global environmental change and sustainability science, providing a single platform to unite research from the natural, social, and applied sciences that seeks to identify and understand:

The drivers, mechanisms, rates, potential thresholds, and long-term context of global environmental change

Safe planetary operating spaces that support long-term human and environmental well-being

Barriers against and strategies that enable the sustainable development of Earth’s ecosystems and natural assets

Transformative social, political, economic, and technological pathways toward a sustainable and equitable future

In addition to publishing original research, One Earth facilitates cross-community dialogue through the publication of opinion pieces, review articles, educational resources, and discussions, surfacing different perspectives on topics of socio-environmental importance.

Enough said

Joao Martins
Reply to  Redge
September 19, 2021 3:27 am

Yes! A biased editorial objective that necessarily indicates the output of biased “scientific” (so called…) information.

Reply to  Redge
September 20, 2021 4:17 pm

Barriers against and strategies that enable the sustainable development of Earth’s ecosystems and natural assets

Transformative social, political, economic, and technological pathways toward a sustainable and equitable future”


September 18, 2021 11:25 pm

It’s overfishing. Climate change, my elbow!

Reply to  Chaswarnertoo
September 19, 2021 7:14 pm

Over population requires over everything .

Barry James
September 18, 2021 11:26 pm

It just beggars belief how often these ignorant doomsayers get surprised when coral reefs, particularly the Great Barrier Reef, don’t die off from “global warming” or “acidification” as they claim they should because that’s what they, in their incompetence, believe should happen. It never seems to occur to them that their incompetence is showing. They even fail to see that their precious “causes” are simply not happening and would not harm corals if they did.

Coral polyps were among the first animals to inhabit the Earth. They have thrived and diversified through every extreme climate that Nature has thrown at them for hundreds of millions of years, yet these dingbats claim they are so well educated that they can justify spending billions of taxpayers dollars to “protect” them from their favourite hobgoblins.

Brian Pratt
Reply to  Barry James
September 19, 2021 7:01 am

Your points are well taken, Barry. However, the early history of corals is pretty uncertain:
Elias, R.J., Lee, D.-J., and Pratt, B.R., 2021, The “earliest tabulate corals” are not tabulates: Geology, v. 49, p. 304–308.

September 19, 2021 12:13 am

Yet more evidence that Academia has totally lost the plot.

Yes, there are a few (usually old) holdouts who care about science, evidence and basic truth.

They dwindle daily and our Beloved Leaders can’t wait for the last of them to peg it.

It won’t end well.

September 19, 2021 2:17 am

They have not “lost the plot”. They have added ‘global warming’ and harvested the money

Ed Hanley
September 19, 2021 12:47 am

Not mentioned in the original paper, but an important metric from the point of view of indigenous people living off the coral fisheries, is the spatial and temporal incidence of ciguatera toxin in fish captured for consumption. The original paper is in my opinion well done and thorough; this seems a missed opportunity to measure something significant.

Reply to  Ed Hanley
September 19, 2021 8:42 am

It reads to me like just another coral reefs “study” where nobody actually got their hair wet when conducting said “study”.

Rod Evans
September 19, 2021 12:51 am

Only a few more weeks left to get those apocalypse now stories into the public domain, ready for highlighting at COP 26. The Guardian’s coordination of climate change articles and dissemination policy of such, continues at pace.
What they are hoping for is a nice cat 5 hurricane to strike the USA so they can role out that “normal natural event” as being the ultimate example of a man made climate change disaster..

Tom in Florida
Reply to  Rod Evans
September 19, 2021 7:24 am

I was lead to believe that COP26 was going to be cancelled due to lack of hookers….. sorry, I meant hotel rooms.

Rod Evans
Reply to  Tom in Florida
September 19, 2021 9:21 am

Well it wouldn’t cancelled due to a lack of climate alarm hucksters, that’s for sure. 🙂

September 19, 2021 1:22 am

Estimates aka guesstimates…

Hey presto it’s all doomed

September 19, 2021 1:28 am

They carefully describe the overfishing, then blame its effects on global warming.

You have to feel sorry for these researchers – or at least for any honest researchers among them – because there’s no grant money for reporting what is actually happening.

Matthew Sykes
September 19, 2021 2:01 am

They survived the 2-3C warmer Holocene Climatic Optimum, they survived sea level rise, they survived the little ice age.

In any case, the GBR is back to 1980s levels, so any problems are not with coral reefs in general, but localised issues. Probably land run off of agricultural pollution.

Pamela Matlack-Klein
September 19, 2021 3:13 am

Interesting how these new journals have sprung up to cater to the alarmist views of some researchers.

Reply to  Pamela Matlack-Klein
September 19, 2021 4:34 am

paid for by whom.

Carbon Bigfoot
Reply to  richard
September 19, 2021 5:51 am

By Pink Floyd’s David Gilmore $160MM.

Peter Barrett
September 19, 2021 3:26 am

Occasionally I feel the “Article Rating” system is lacking. There should be a circle representing a zero vote to the left of the five stars. I will not be placing a vote for this piece of climate grifters’ work as giving it one whole star would indicate unwarranted praise.

Reply to  Peter Barrett
September 20, 2021 5:47 pm

Eleven stars with a center ‘no accomplishments – no harm – no value’ star; left of center stars to be bilious green, right of center the current gold stars.

September 19, 2021 3:51 am

Coral and fish are thriving at Bikini atoll. Of course man does not got there. Amazing how climate change is so selective.

Reply to  richard
September 19, 2021 8:45 am

That would be Bikini 2.0.
The original version was obliterated in the 1950s by A-bomb testing.

Gary Pearse
September 19, 2021 4:27 am

Eddy, you are a Newfie a resident of Newfoundland and Labrador. You are in the largest fisheries area on the globe. Factory ships from around the world had depleted cod stocks by the latter half of the 20th century by massive over-fishing.

Didn’t your grandfather tell you this? The world population has trippled since 1950 and the over-fishing had already been recognized by then. You mention that fishing had been cut back. This was because laws were promulgated to deal with over-fishing, not because of bio-effing diversity problems!

Did you know that Iceland went to war against Britain over plunderingof of their fish stocks? They actually fired from gunboats at big fishing vessels, cut their nets, rammed fishing boats.

The “200 mile limit” came out of all this. Eddy, you got de-educated at UBC.

Alan the Brit
Reply to  Gary Pearse
September 20, 2021 12:40 am

With respect, the ramming was done by Icelandic fishing vessels against Royal Navy Frigates!!! The steel skin of a Frigate is very thin & substantial damage was caused by these heavily built fishing boats!!!

H. D. Hoese
September 19, 2021 6:45 am

“The real world is muddy and messy and full of things that we do not yet understand. It is much easier for a scientist to sit in an air-conditioned building and run computer models, than to put on winter clothes and measure what is really happening outside in the swamps and the clouds. That is why the climate model experts end up believing their own models.” Freeman Dyson, died at 96.

   Melnychuk M. C., et al.,2020. Global trends in status and management of assessed stocks: achieving sustainable fisheries through effective management. FAO Fisheries and Aquaculture Tech. Pap. 665. Rome.

6.12 FAO Major Fishing Area 81—Pacific, Southwest p 105
“In summary, this region is characterized by a sharp change fishing pressure around
2000, with a rapid increase to levels greater than UMSY before 2000 and a rapid decrease
since then. Biomass has not changed to the same degree, although with fishing
pressure now back down near UMSY they may be expected to in coming years. There
is little significant potential for increasing overall yield from either over-exploited
or under-exploited stocks. Some stocks remain overfished and are of management
concern. Of the total FAO landings in this region, only 18 percent are derived from
unassessed or not-recently-assessed stocks”

September 19, 2021 7:11 am

This study seems to have made very thorough use of a wide variety of observational data sources… coral reef surveys, fishery catch reports etc etc.

Is anyone her presenting any actual detailed evidence in contradiction?

Reply to  griff
September 19, 2021 8:05 am

Not many studies were undertaken earlier than the 1950’s, governments only had fisheries departments to levy taxes, and fishing seasons and limits were mostly to maximize tax revenue. So there isn’t much evidence to contradict this study, also not much to confirm their causation hypotheses.

Steve Oregon
Reply to  griff
September 19, 2021 8:21 am

One could observe the Oregon’s Commercial Dungenus Crab landings over time and see a very well managed, healthy & sustainable marine habitat.

That despite Oregon academia’s mendacious concocting of AGW Ocean Dead Zones that they falsely claimed were a result of climate change, new, bigger, lasting longer and reaching a tipping point of marine doom.
This fraud, led by one of the worst academics Jane Lubchenco, has gone without any consequences or accountability. Such is the nature of modern science?

Reply to  griff
September 19, 2021 8:53 am

Griff, all I would offer is a face-palm over the “climate change” bit.

Geoff Sherrington
Reply to  griff
September 19, 2021 5:34 pm

There is the Great Barrier Reef that few people have seen (as opposed to near shore island reefs) that is so big that it is a case of its own.
There is a trivial density of fishing on the GBR.
There is increasing evidence that the sea surface temperature has not changed there since 1871. (See bomwatch blog).
There are severe methodology problems with all measurements of GBR health.
There is measured evidence that agricultural products like fertiliser and suspended soils seldom reach the main part of the GBR. Read Peter Ridd’s research.
There is strong evidence that the GBR is a political football in global play. Sad.
Geoff S

Alan the Brit
Reply to  griff
September 20, 2021 12:44 am

Still waiting for your reply to my question, telling one & all when there was a period in the last four & a half billion years of Earth’s history when the climate stayed the same!!!

Bill Rocks
September 19, 2021 8:34 am

Overfishing and despoiling reefs. Sport hunting polar bears during the 20th century.

September 19, 2021 8:56 am

Back in the early seventies I visited several islands in the Caribbean and saw many small houses and a lot of bars. Not many hotels and drinking seemed to be the favorite tourist pastime. Recently I visited some of these same islands which had hundreds of high rise apartments, many very upscale hotels, and several cruise ships in port. There was a huge industry obvious to cater to tourist with zip lines, dive operations, souvenir shops, and many, many seafood eateries. I’m surprised there was a single fish left in the ocean within a hundred miles. About 30 years ago I visited a small island that catered to only divers. I went on a night dive in the protected waters in which fishing was illegal. After my dive, while waiting for others to rejoin us, I asked what all the lights were all round us. The boat captain only smiled and said poachers. Can anyone be surprised at the declining harvest.

michael hart
September 19, 2021 12:47 pm

“After putting it all together, the data show that the global coverage of living corals has declined by about half since the 1950s.”

Yeah, right. A real scientist would ask “Prove to me that you are adequately sampling global living corals.”

You are probably only sampling the places where your grant funding allows you to go scuba diving.

Go and do a Ph.D. where you stand on your feet for 70+ hours a week in front of a fume-hood. (I’ll also concede that I could see a snow-capped mountain outside the doors of the building.)

September 20, 2021 12:24 pm

Bizarre logic and near zero absolutes of real data are strong in this paper.

That is, without confirmation bias and imaginary data, they wouldn’t have a paper.

Global fishing effort for coral-reef-associated species in EEZs with coral reefs increased from 1950–2010 (Figure S5), and the resulting catch-per-unit effort (CPUE) trend peaked in 1971, after which it decreased—an indication of declining coral reef fish abundance in many countries (Figure 3B). “

Their absurd fisheries logic is directly tied to their absurd coral reefs’ logic.
Zero data at the beginning is ignored as they make absurd assumptions for both fisheries and coral reefs.

Of course fishing effort increased as fishing populations were identified and added to their model.

Then there is another gross assumption that decline in ‘reef associated’ fish is automatically blamed on less coral.

Another circular argument endless cycle where gross assumptions are direct causes for other gross assumptions.

No effort was made into a myriad of other causes.

  • e.g., subsistence reef fishers obtained employment elsewhere and were no longer fishing.
  • e.g. 2, that localized reef fish suffered population declines from overfishing. A primary concern for fish populations worldwide right now.
  • e.g. 3, governments declaring reefs as sanctuaries and banning fishing.
  • etc. etc.
September 21, 2021 3:50 pm

When do we talk about how they based their study on guesses of how much coral cover there was in the 50s. You know since they don’t have actual data? They just asked current experts to estimate how much there was.

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