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

Turkey: No Ransom Paid for Release of Hostages Held by IS Militants

President Erdogan hails release of hostages as diplomatic success but declines to be drawn on whether their release freed Ankara's hand to take more active stance against insurgents More

Audio Sierra Leone Ends Ebola Lockdown

Health ministry says it has reached 75 percent of its target of visiting 1.5 million homes to locate infected, educate population about virus More

US Pivot to Asia Demands Delicate Balancing Act

As tumult in Middle East distracts Obama administration, efforts to shift American focus eastward appear threatened 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.
Natural Gas Export Plan Divides Maryland Towni
X
Deborah Block
September 21, 2014 2:12 PM
A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Natural Gas Export Plan Divides Maryland Town

A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Difficult Tactical Battle Ahead Against IS Militants in Syria

The U.S. president has ordered the military to intensify its fight against the Islamic State, including in Syria. But how does the military conduct air strikes in a country that is not a U.S. ally? VOA correspondent Carla Babb reports from the Pentagon.
Video

Video Iran, World Powers Seek Progress in Nuclear Talks

Iran and the five permanent members of the U.N. Security Council plus Germany, known as the P5 + 1, have started a new round of talks on Iran's nuclear program. VOA State Department correspondent Pam Dockins reports that as the negotiations take place in New York, a U.S. envoy is questioning Iran's commitment to peaceful nuclear activity.
Video

Video Alibaba Shares Soar in First Day of Trading

China's biggest online retailer hit the market Friday -- with its share price soaring on the New York Stock Exchange. The shares were priced at $68, but trading stalled at the opening, as sellers held onto their shares, waiting for buyers to bid up the price. More on the world's biggest initial public offering from VOA’s Bernard Shusman in New York.
Video

Video Obama Goes to UN With Islamic State, Ebola on Agenda

President Obama goes to the United Nations General Assembly to rally nations to support a coalition against Islamic State militants in Iraq and Syria. He also will look for nations to back his plan to fight the Ebola virus in West Africa. As VOA White House correspondent Luis Ramirez reports, Obama’s efforts reflect new moves by the U.S. administration to take a leading role in addressing world crises.
Video

Video Migrants Caught in No-Man's Land Called Calais

The deaths of hundreds of migrants in the Mediterranean this week has only recast the spotlight on the perils of reaching Europe. And for those forunate enough to reach a place like Calais, France, only find that their problems aren't over. Lisa Bryant has the story.
Video

Video Westgate Siege Anniversary Brings Back Painful Memories

One year after it happened, the survivors of the terror attack on Nairobi's Westgate Shopping Mall still cannot shake the images of that tragic incident. For VOA, Mohammed Yusuf tells the story of victims still waiting for the answer to the question 'how could this happen?'
Video

Video Militant Assault in Syria Displaces Thousands of Kurds

A major assault by Islamic State militants on Kurds in Syria has sent a wave of new refugees to the Turkish border, where they were stopped by Turkish border security. Turkey is already hosting about 700,000 Syrian refugees who fled the civil war between the government and the opposition. But the government in Ankara has a history of strained relations with Turkey's Kurdish minority. Zlatica Hoke reports Turkey is asking for international help.
Video

Video Whaling Summit Votes to Uphold Ban on Japan Whale Hunt

The International Whaling Commission, meeting in Slovenia, has voted to uphold a court ruling banning Japan from hunting whales in the Antarctic Ocean. Conservationists hailed the ruling as a victory, but Tokyo says it will submit revised plans for a whale hunt in 2015. Henry Ridgwell reports from London.
Video

Video A Dinosaur Fit for Land and Water

Residents and tourists in Washington D.C. can now examine a life-size replica of an unusual dinosaur that lived almost a hundred million years ago in northern Africa. Scientists say studying the behemoth named Spinosaurus helps them better understand how some prehistoric animals adapted to life on land and in water. The Spinosaurus replica is on display at the National Geographic museum. VOA’s George Putic has more.
Video

Video Iraqi Kurdistan Church Helps Christian Children Cope find shelter in churches in the Kurdish capital, Irbil

In the past six weeks, tens of thousands of Iraqi Christians have been forced to flee their homes by Islamic State militants and find shelter in churches in the Kurdish capital, Irbil. Despite U.S. airstrikes in the region, the prospect of people returning home is still very low and concerns are starting to grow over the impact this is having on the displaced youth. Sebastian Meyer reports from Irbil on how one church is coping.


Carnage and mayhem are part of daily life in northern Nigeria, the result of a terror campaign by the Islamist group Boko Haram. Fears are growing that Nigeria’s government may not know how to counter it, and may be making things worse. More

AppleAndroid