News / Science & Technology

Warmer Oceans Could Mean Smaller Fish

Changes in ocean and climate systems due to global warming could lead to smaller fish. (Credit: Halseike Creative Commons)
Changes in ocean and climate systems due to global warming could lead to smaller fish. (Credit: Halseike Creative Commons)
Rosanne Skirble
Summers in the Scandinavian Arctic are the warmest they've been in nearly 2,000 years, and this warming of the oceans worldwide could be leading to smaller fish, which has major implications for global fisheries, according to two new studies.  
 
Warmer oceans

William D’Andrea studies how Earth’s climate changes over time. In an article just published in the journal Geology, the associate professor at Columbia University’s Lamont-Doherty Earth Observatory charts 1,800 years of Arctic climate history, based on his analysis of sediment from a lake in the Norwegian archipelago of Svalbard.  
 
“This location hasn’t been as warm in the last 1,800 years as it has been in the last two decades,” he says.
From this small platform perched atop two inflatable rafts, these scientists are able to take sediment cores from the lake floor below. (Credit: Marthe Gjerde)From this small platform perched atop two inflatable rafts, these scientists are able to take sediment cores from the lake floor below. (Credit: Marthe Gjerde)
x
From this small platform perched atop two inflatable rafts, these scientists are able to take sediment cores from the lake floor below. (Credit: Marthe Gjerde)
From this small platform perched atop two inflatable rafts, these scientists are able to take sediment cores from the lake floor below. (Credit: Marthe Gjerde)

D’Andrea and his colleagues reconstructed that climate history by examining traces of algae in the organic material and minerals that settled to the Arctic lake bottom over the millennia.

Scientists know that algae living in cooler water produce lots of unsaturated fats. In warmer water, they produce less. By measuring the fat content in algae retrieved in lake-bottom core samples, D’Andrea was able to track the Earth’s temperature over thousands of years.
 
“So what we have are little thermometers," he says. "These algae are producing thermometers and dropping them into the sediment and leaving them behind.”

Climate Change in Warmer World
Climate Change in Warmer Worldi
|| 0:00:00
...
 
🔇
X

 
D’Andrea says local air temperature records for the past 100 years match what he found in the lake-bottom sediment for the same period. He says the unique algae signatures can help scientists look into the past to see how Earth’s climate system behaves.
Glaciers on western Svalbard have been retreating for at least the past 100 years. The lake in the foreground can be used to study past changes in glacier activity. (Credit: William D'Andrea)Glaciers on western Svalbard have been retreating for at least the past 100 years. The lake in the foreground can be used to study past changes in glacier activity. (Credit: William D'Andrea)
x
Glaciers on western Svalbard have been retreating for at least the past 100 years. The lake in the foreground can be used to study past changes in glacier activity. (Credit: William D'Andrea)
Glaciers on western Svalbard have been retreating for at least the past 100 years. The lake in the foreground can be used to study past changes in glacier activity. (Credit: William D'Andrea)

“And once we understand that, we get a better handle on how it does behave and why it responds in certain ways to different types of forcing, whether those forcing mechanisms are based on the sun’s output or volcanic eruptions or the level of greenhouse gases in the atmosphere,” D’Andrea says.

He adds that a clear picture of our climate history is essential to making accurate projections of our climate future.

Smaller fish
 
A second new study, published in the journal Nature Climate Change, looks at how fish are responding to rising ocean temperatures.  Lead author William Cheung and colleagues at the University of British Columbia’s Fisheries Centre, used computer models to project climate-induced physical changes in more than 600 species of fish.
 
“What we find is that across different ocean basins, meaning Pacific, Indian or Atlantic oceans, we are seeing on average around 14 to 24 percent reductions in maximum body size of the fish species that we investigated by 2050 relative to now,” Cheung says.
 
As the atmosphere is warmed by heat-trapping emissions from fossil-fueled power plants, buildings and automobiles, so too is the ocean.  And in a warmer ocean, there is less dissolved oxygen available to fish, who need it for normal growth.      

“So at some point the fish will stop growing because they just cannot get sufficient oxygen to support growth in addition to maintaining their normal body function,” Cheung says.  
 
The study is the first to predict that a warmer ocean could mean smaller fish in the decades ahead.  It also suggests that global warming may exacerbate the damage to fish populations already being done through overfishing, pollution and habitat loss.
 
“If you look at the fish population that is already depleted, that their critical habitat are deteriorated, they have a smaller capacity to respond to climate change compared to fish populations that are still abundant or that they are well managed and in good condition," Cheung says. "So we need to manage our marine ecosystems effectively as well.”
 
Cheung says the study concludes that failure to curb climate-changing greenhouse-gas emissions could risk further damage to marine ecosystems, global fisheries and an essential source of the world’s food.

You May Like

Elusive Deal With Iran Could Yield Foreign Policy Legacy for Obama

A new Iranian leader -- and a strategic shift by the United States -- opens narrow window for nuclear agreement with Tehran More

Column: Saudi-Iran Meeting Could Boost Fight Against Islamic State

The fact that Iranians and Saudis are talking again does not guarantee a breakthrough, but it could make it easier to build a broad coalition against IS More

Thai Ruler Gives Top Cabinet Posts to Junta Inner Circle

Thailand's army chief has kept an iron grip on power as he extends the government, hand-picking an interim parliament that subsequently nominated him prime minister More

This forum has been closed.
Comment Sorting
Comments
     
by: Anonymous
October 15, 2012 2:11 PM
Charlie--
Please study some more, friend. They just explained how they have accurate records at that location going back 1,800 years (little "algae thermometers"), and there are dozens of other reliable sources of historic temperature data (cherry blossom tree dates in Japan, air trapped in ice cores in Greenland, fossilized tree rings, lake sediments, and many more).
The Earth is NOT cooling. And far more than 16ppm of CO2 were added by humans--pre-Industrial Revolution concentrations were around 275ppm. Deforestation, coal, and oil have contributed the rest.
Al Gore did not invest this science. But he and other very smart people believe it. Look up James Hansen, or Bill McKibben, or Jared Daimond--and then find one scholar of their caliber who denounces climate change. Find just one, who isn't funded by fossil fuels.
I don't think you can do it.


by: rlaqkgnl from: Yougtong dong, Suwon, S.K
October 10, 2012 3:32 AM
Then how about the whales?


by: Charlie from: North Yorkshire
October 09, 2012 12:21 PM
Accurate records only go back 100 years. I wonder what happened 1,800 years ago? Actually the Chinese sailed through the North West Passage in the 1400's and a British Nuclear submarine broke through the ice at the North pole in the Summer of 1987, before the Global Warming hysteria and Algore's $Billions. Remember, the current levels of CO2 in the atmosphere (395 ppm) only 16 parts per million are man made. That may explain why the Earth is cooling and that Antarctic Sea ice is at its greatest extent recorded. Small fish are most likely to do with over fishing and over fishing is caused by overpopulation.

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
West Africa Ebola Vaccine Trials Possible by Early 2015i
X
Carol Pearson
August 30, 2014 7:14 PM
A U.S. health agency is speeding up clinical trials of a possible vaccine against the deadly Ebola virus that so far has killed more than 1,500 people in West Africa. If successful, the next step would be a larger trial in countries where the outbreak is occurring. VOA's Carol Pearson has more.
Video

Video West Africa Ebola Vaccine Trials Possible by Early 2015

A U.S. health agency is speeding up clinical trials of a possible vaccine against the deadly Ebola virus that so far has killed more than 1,500 people in West Africa. If successful, the next step would be a larger trial in countries where the outbreak is occurring. VOA's Carol Pearson has more.
Video

Video Survivors Commemorate 70th Anniversary of Nazi Liquidation of Jewish Ghetto

When the German Nazi army occupied the Polish city of Lodz in 1939, it marked the beginning of a long nightmare for the Jewish community that once made up one third of the population. Roughly 200,000 people were forced into the Lodz Ghetto. Less than 7,000 survived. As VOA’s Kane Farabaugh reports, some survivors gathered at the Union League Club in Chicago on the 70th anniversary of the liquidation of the Lodz Ghetto to remember those who suffered at the hands of the Nazi regime.
Video

Video Cost to Raise Child in US Continues to Rise

The cost of raising a child in the United States continues to rise. In its latest annual report, the U.S. Department of Agriculture says middle income families with a child born in 2013 can expect to spend more than $240,000 before that child turns 18. And sending that child to college more than doubles that amount. VOA’s Deborah Block visited with a couple with one child in Alexandria, Virginia, to learn if the report reflects their lifestyle.
Video

Video Chaotic Afghan Vote Recount Threatens Nation’s Future

Afghanistan’s troubled presidential election continues to be rocked by turmoil as an audit of the ballots drags on. The U.N. says the recount will not be completed before September 10. Observers say repeated disputes and delays are threatening the orderly transfer of power and could have dangerous consequences. VOA correspondent Meredith Buel reports.
Video

Video Ukraine Battles Pro-Russia Rebel Assault

After NATO concluded an emergency meeting to discuss the crisis in eastern Ukraine, the country is struggling to contain heavy fighting near the strategic port of Mariupol, on the Azov Sea. Separatist rebels are trying to capture the city, allegedly with Russian military help, and Ukraine's defense forces are digging in. VOA's Daniel Schearf spoke with analysts about what lies ahead for Ukraine.
Video

Video Growing Business Offers Paint with a Twist of Wine

Two New Orleans area women started a small business seven years ago with one thing in mind: to help their neighbors relieve the stress of coping with a hurricane's aftermath. Today their business, which pairs painting and a little bit of wine, has become one of the fastest growing franchises across the U.S. VOA’s June Soh met the entrepreneurs at their newest franchise location in the Washington suburbs.
Video

Video Ebola Vaccine Trials To Begin Next Week

The National Institutes of Health says it is launching early stage trials of a vaccine to prevent the Ebola virus, which has infected or killed thousands of people across West Africa. The World Health Organization says Ebola could infect more than 20,000 people across the region by the time the outbreak is over. The epidemic has health experts and governments scrambling to prevent more people from becoming infected. Zlatica Hoke has more.
Video

Video Asian Bacteria Threatens Florida Orange Trees

Florida's citrus fruit industry is facing a serious threat from a bacteria carried by the Asian insect called psyllid. The widespread infestation again highlights the danger of transferring non-native species to American soil. VOA’s George Putic reports.
Video

Video Aging Will Reduce Economic Growth Worldwide in Coming Decades

The world is getting older, fast. And as more people retire each year, fewer working-age people will be there to replace them. Bond rating agency Moody’s says that will lead to a decline in household savings; reducing global investments - which in turn, will lead to slower economic growth around the world. But experts say it’s not too late to mitigate the economic impact of the world’s aging populations. Mil Arcega has more.
Video

Video Is West Doing Enough to Tackle Islamic State?

U.S. President Barack Obama has ruled out sending ground troops to Iraq to fight militants of the so-called Islamic State, or ISIS, despite officials in Washington describing the extremist group as the biggest threat the United States has faced in years. Henry Ridgwell reports from London on the growing uncertainty over whether the West’s response to ISIS will be enough to defeat the terrorist threat.
Video

Video Coalition to Fight Islamic State Could Reward Assad

The United States along with European and Mideast allies are considering a broader assault against Islamic State fighters who have spread from Syria into Iraq and risk further destabilizing an already troubled region. But as VOA State Department Correspondent Scott Stearns reports, confronting those militants could end up helping the embattled Syrian President Bashar al-Assad.
Video

Video Made in America Socks Get Toehold in Online Fashion Market

Three young entrepreneurs are hoping to revolutionize the high-end sock industry by introducing all-American creations of their own. And they’re doing most of it the old-fashioned way. VOA’s Julie Taboh recently caught up with them to learn what goes into making their one-of-a-kind socks.
Video

Video Americans, Ex-Pats Send Relief Supplies to West Africa

Health organizations from around the world are sending supplies and specialists to the West African countries that are dealing with the worst Ebola outbreak in history. On a smaller scale, ordinary Americans and African expatriates living in the United States are doing the same. VOA's Carol Pearson reports.

AppleAndroid