Shark species face extinction amid overfishing and appetite for fins

ALOK JHA – THE GUARDIAN

Nine more species of shark are to be added to the endangered list as scientists warn that oceans are being emptied of the fish by overfishing and finning.

The scalloped hammerhead shark, which has declined by 99% over the past 30 years in some parts of the world, is particularly vulnerable and will be declared globally endangered on the World Conservation Union (IUCN) list.

“Sharks are definitely at the top of the list for marine fishes that could go extinct in our lifetimes,” said Julia Baum of the Scripps Institution of Oceanography in California and a member of IUCN shark specialist group. “If we carry on the way that we are, we’re looking at a really high risk of extinction for some of these shark species within the next few decades.”

At the American Association for the Advancement of Science annual meeting in Boston yesterday, Baum said that in addition to the scalloped hammerhead, other shark species that will be added to the revised IUCN endangered list later this year are the smooth hammerhead, shortfin mako, common thresher, big-eye thresher, silky, tiger, bull and dusky. There are already 126 species of shark on the IUCN’s list.

“The perception has been that really wide-ranging species can’t become endangered because if they are threatened in one area, surely they’ll be fine in another area,” said Baum. “But fisheries now cover all corners of the earth and they’re intense enough that these species are being threatened everywhere.”

Recent studies have shown that all shark populations in the north-west Atlantic Ocean have declined by an average of 50% since the early 1970s.

Shark numbers can become depleted very quickly because they take a long time to mature – 16 years in the case of a scalloped hammerhead. Their fins are highly prized in China and can fetch up to £140 a kilogram. Until recently the eating of shark fin was a delicacy restricted to the rich in China, said Baum, but as the country’s middle class has grown in the past 25 years, so has the market for shark fins.

Excessive fishing has caused a 90% decline in shark populations across the world’s oceans and up to 99% along the US east coast, which are some of the best-managed waters in the world, according to Baum.

The decline in predators such as sharks can have devastating consequences for the local marine ecology.

In a case study published last year, Baum found that a major decline in the numbers of predatory sharks in the north Atlantic after 2000 had allowed populations of the sharks’ prey, cownose rays, to explode. The rays in turn decimated the bay scallop populations around North Carolina. “There was a fishery for bay scallops in North Carolina that lasted over a century uninterrupted and it was closed down in 2004 because of cownose rays.”

Fishing for sharks in international waters is unrestricted, but Baum supports a recent UN resolution calling for immediate limits on catching sharks and a ban on shark finning.

Sonja Fordham, of the Shark Alliance, a coalition of 50 scientific and conservation groups, said: “People think these wide-ranging, fast sharks are resilient to fishing; however, this shows this is not the case. Concerned citizens can really help by making their fisheries ministers aware that they support conservation measures such as catch limits.”

Some conservation efforts for sharks will focus on newly identified hotspots where sharks congregate during migrations. Peter Klimley of the University of California, Davis, found that scalloped hammerhead sharks migrate along fixed “superhighways” in the oceans, speeding between a series of “stepping stone” sites near coastal islands ranging from Mexico to Ecuador.

“Hammerhead sharks are not evenly dispersed throughout the seas, but concentrated at seamounts and offshore islands,” he said. “Hence, enforcing reserves around these areas will go far in protecting these species and will provide the public with places for viewing sharks in their habitat.”

One site between Hawaii and Mexico attracts so many sharks it has become known among scientists as “the white shark cafe”, Klimley says.

“We started calling it the cafe because that is where you might go to have a snack or maybe just to ‘see and be seen’. We are not sure which,” said Salvador Jorgensen, a researcher at Stanford University’s Hopkins Marine Station.

“Once they leave the cafe they return year after year to the same exact spot along the coast, just as you might return to a favourite fishing hole.”

Critically Endangered Porpoise May Be Doomed To Extinction

 Science Daily – Press Release

ScienceDaily (Jan. 16, 2008) — An international research team, including biologists from NOAA’s Fisheries Service, reported in the scientific journal Conservation Biology, that the estimated population of vaquita, a porpoise found in the Gulf of California, is likely two years away from reaching such low levels that their rate to extinction will increase and possibly be irreversible. Scientists believe only about 150 vaquita remain.

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The research team, led by Armando Jaramillo, Instituto Nacional de Ecología, Mexico, included researchers Barbara Taylor, NOAA’s Fisheries Service, and Randy Reeves Reeves, Chair of the Cestacean Specialist Group, IUCN — the World Conservation Union.

The group assessed the number of vaquita based on past estimates of abundance and deaths in fishing nets together with current fishing effort. Approximately 30 vaquita drown each year in the Gulf of California when they become entangled in nets set for fish and shrimp.

Vaquita are found only in a small area of productive, shallow water in the northernmost Gulf of California. They are listed as endangered species by the United States and Mexico and critically endangered by the World Conservation Union.

Researchers cite worrisome parallels between vaquita and the baiji, a freshwater dolphin in the Yangtze River, which was recently declared likely to be extinct; primarily from entanglement in fishing gear.

Adapted from materials provided by NOAA National Marine Fisheries Service, via EurekAlert!, a service of AAAS.

New fish quota to protect plaice and sole

For years European Union fishermen have seen a reduction in their fishing quotas. This is meant to keep the maritime species from dying out. Recently the situation has seen a slight improvement and the numbers of some species in European waters are stabilising. On Wednesday, the EU’s Executive Committee announced its recommended quotas for next year. The quotas will again be lowered and fewer fish will be caught than in previous years. The European fishing quotas are determined on the basis of advice given by various experts, including Dutch biologists, and the IMARES research institute which specialises in marine ecology research.

Radio Netherlands Worldwide

Two biologists are on their hands and knees on the deck of a ship sailing the Wadden Sea. They are searching for fish such as plaice, sole, whiting, crabs and shrimp – sometimes they even find a jellyfish. The boats fish at different spots during the day. According to Marcel de Vries of IMARES:

“Each year we fish at 130 fixed locations. We return every year and we compare what we find and what we caught in previous years.”

At every spot an enormous fishing net splashes into the sea, where it remains for 15 minutes. Sometimes the net is full of junk; other times it is teeming with fish.

Plaice and sole
Plaice and sole are the most important species in the Dutch fishing trade, which is why the study placed special emphasis on the two flatfish. Biologist Loes Bolle says the fishing expeditions are only a minor part of the extensive research which determines European Union advisory policies.

“We count fish in all Dutch waters, but the same happens in Germany, Belgium, England and Denmark. We also estimate how many fish are caught by fishermen. We combine the statistics in an attempt to determine how many fish can be caught without threatening the species’ survival.”

After the fish are counted on the Wadden Sea, each one is measured to determine the proportion of smaller and younger fish, or young and old.

Thankless task
In the course of the day the scientists spend many hours on their knees, counting and measuring hundreds of plaice and sole. But the work seems thankless, since the politicians will probably ignore their advice. Biologist Loes Bolle says they are more concerned about protecting the economic interests of the fishing industry, which means they’ll often allow an increase in the quotas.

“We give biologically responsible advice, in other words, we do our best to recommend how fish can be caught in a sustainable manner. We are attempting to help fishermen keep the population at a viable level so that the species can survive. The best course of action would be to ban fishing for the time being, but that is not realistic. We do our best to ensure that enough fish will survive so that the species do not become extinct. This will also guarantee that fishing does not become extinct.”

Biologists are recommending a reduction in the quota for plaice and sole in 2008. It’s now the politicians’ turn, beginning with the European Commission.

Mediterranean Sharks and Rays in Danger of Extinction

The Scottish Sea Angling Conservation Network

A report released today by the IUCN Shark Specialist Group (SSG) and the IUCN Centre for Mediterranean Cooperation reveals that the region has the highest percentage of such species assessed as Threatened in the world, due primarily to overfishing through targeted and incidental fisheries.

SSACN is a member of the Shark Alliance which is repeating its call for a strong Plan of Action to improve the status of European sharks and rays in response to new IUCN findings.

European Union (EU) resource managers, are developing an overdue Plan of Action for the conservation and management of sharks. The European Commission is expected to propose the first EU limits for porbeagle shark, identified by IUCN as “Critically Endangered” off Europe, by the end of November for consideration by EU Fisheries Ministers in December.

The report deemed 42% (30 species) of these species Threatened, of which 18% are Critically Endangered, 11% Endangered and 13% Vulnerable. Another 18% (13 species) were assessed as Near Threatened while a lack of information led to 26% (18 species) being classified as Data Deficient. Only 14% (10 species) are considered to be of Least Concern.

The Scottish Government should do something to address the £4.7 million worth of sharks were landed in Scotland.

Never before have the EU’s Mediterranean countries had more reason or opportunity to safeguard the region’s beleaguered sharks and rays.

USA. Scientists call for Lower Snake Dam removal to help endangered Orcas

BYM Marine Environment News

Leading Northwest scientists and orca advocates are urging NOAA Fisheries to consider removal of the four lower Snake River dams in order to protect endangered Puget Sound orca populations that need Columbia-Snake River salmon as a critical food source.

“Restoring Columbia River Chinook salmon is the single most important thing we can do to ensure the future survival of the Southern Resident Community of killer whales,” said Dr. Rich Osborne, research associate with The Whale Museum in Friday Harbor, WA. “We cannot hope to restore the killer whale population without also restoring the salmon upon which these whales have depended for thousands of years. Their futures are intricately linked.”

The comments from the six prominent orca scientists, delivered in a letter to Northwest members of Congress and NOAA regional administrator Robert Lohn, came in response to the Oct. 31 release of a new draft Biological Opinion from NOAA Fisheries for Columbia-Snake River salmon management. Salmon advocates say the new plan, the result of a court-ordered rewrite of an earlier, illegal 2004 federal salmon plan, fails to do enough to recover imperiled salmon in the seven-state Columbia-Snake river basin, and ignores altogether the four dams on the lower Snake River that do the most harm to these fish.

“History will not be very forgiving of the resource managers who failed in their responsibilities to these icons of the Pacific Northwest, Chinook and orca,” said Ken Balcomb, senior scientist with the Center for Whale Research.

“The draft plan relies heavily on actions that science and time have proven will not restore these fish to the levels necessary for self-sustaining populations of salmon, or abundant enough to provide a healthy food resource for these killers whales,” said Dr. David Bain, a killer whale biologist at Friday Harbor Labs. “Not only are salmon from the Columbia River an important historic food source, recovered abundant salmon in this river are an indispensable requirement for the future recovery of Southern Residents.”

“The new Federal salmon plan for the Columbia and Snake rivers is no better than previous plans in providing access to the basin’s best remaining salmon habitat in the upper reaches of the Snake River,” said Howard Garrett, co-founder of the Orca Network. “The resulting declining salmon runs have a very real impact on the 88 endangered southern resident orcas that depend on these fish, as they have for centuries. As the salmon disappear, the orcas go hungry.”

“The best science tells us,” Garrett added, “that to revitalize Snake River salmon, we’ll need to bypass the dams that block fish passage, and that dam removal, combined with a variety of economic investments, will bring benefits to upriver communities in eastern Washington as well as to Puget Sound.”

The Columbia and Snake River Basin was once the world’s most productive salmon watershed, with tens of millions of fish returning annually. Today, returns hover near 1% of those historic levels. More than 200 large dams on the basin’s rivers are the major cause of this crisis, with 13 populations now listed under the Endangered Species Act, and four directly impacted by the lower Snake River dams. Yet, the Columbia-Snake Basin still holds more acres of pristine salmon habitat than any watershed in the lower 48 states.

It is this opportunity, notes Kathy Fletcher, executive director of People For Puget Sound, that we must take advantage of, if we hope to protect and restore these two iconic Northwest species whose fates are inexorably intertwined.

“Our leaders must look for solutions not only in Puget Sound, but also in the rivers that bring the salmon to the sea throughout the Northwest,” Fletcher said. “The great salmon rivers like the Columbia and Snake can once again produce the healthy runs of Chinook, on which our majestic orcas feed, but only if we recover salmon habitat. We must act quickly to restore clean water, abundant, sustainable salmon populations, and a safe home for orcas. The scientists tell us there is no time to waste.”

86% of sea turtle species threatened with extinction

Mongabay

Marine turtles have thrived for more than 100 million years. But only the last few hundred years have given the huge, spectacular, prehistoric reptiles serious trouble.

And that’s where people like Earl Possardt, an international sea turtle specialist with the U.S. Fish and Wildlife Service, come in. Possardt is part of a bigger effort to rescue what remains of seven species of an animal that has managed, sometimes against formidable odds, to make it all the way into the 21st century.

In 2007 alone, the U.S. Fish and Wildlife Service directed international conservation grants totaling nearly $600,000 to 22 countries and conservation entities involved in sea turtle survival. Most of the money has gone to efforts to restore or safeguard turtle nesting areas. The funds also support conservation of the world’s largest nesting loggerhead population in Oman, and help preserve one of the two remaining large leatherback nesting areas that occur along the West African coast.

Possardt said that overall, he has seen some positive response, but acknowledges that progress is “a mixed bag. We know how to conserve turtles, but we also know it takes a long time.”

Myriad threats continue to plague sea turtles around the globe, but it was the growth of the shrimping industry following World War II that took a significant toll on turtle populations. Turtles are able to swim long distances under water, but must eventually surface for air. Trapped in shrimp trawls, thousands drowned. The eventual use of “excluder” devices by shrimp trawlers, which enable trapped turtles to escape while shrimp remain caught, has dramatically alleviated the problem.

But the turtles still face legal or illegal over-exploitation of their eggs or meat, depredation of eggs by predators, disorienting light pollution that can confuse nesting females and disorient hatchlings, and degradation of important habitat, including grass beds and coral reefs.

Poaching remains a potent threat. Last September, Fish and Wildlife Service law enforcement agents and authorities in Mexico arrested 12 people involved in the black market sea turtle trade. The 3-year undercover investigation snared suppliers, manufacturers, wholesalers, retailers and smugglers who were dealing in products made from hundreds of sea turtle skins or pieces of turtle shells.

If that isn’t enough, Mother Nature has placed its own natural restrictions on the turtles – hawksbill turtles may not reach sexual maturity until they are 30 years old; it can take loggerheads 12 to 30 years, and green sea turtles, somewhere between 20 and 50 years before they can reproduce, delaying the ability of populations to recover.

Because of some or all of those problems, species like the Pacific leatherback remain in dire shape; the East Pacific population, formerly the world’s largest leatherback nesting aggregation as recently as the 1980s, is now reduced to fewer than 500 females nesting annually on beaches in Mexico and Costa Rica. They face continued threats from poachers, and the Service and NOAA Fisheries continue to work with the fishing industry to minimize dangers to the turtles from long lines and gillnets.

But there are bright spots. Possardt notes that the Kemp’s ridley sea turtle represents a success story. On the verge of extinction in the 1980s, the Kemp’s ridley was down to as few as 700 known nests in 1985, from the tens of thousands of nests counted annually in the 1940s, due to the aggressive harvest of eggs and females as well as a high mortality from shrimp trawlers. But a serious conservation effort on the part of the Mexican government, initiated in the 1960s and joined by the Service in the 1970s, managed to turn the tide for the Kemp’s ridley, and today the turtle is in much better shape.

Of the seven sea turtle species that remain on the planet, six are considered imperiled; only the flatback turtle, found in the waters off Australia, is not on anyone’s endangered list.

Turtle grants are made possible by the Marine Turtle Conservation Act of 2004, enacted by the Congress and administered by the Service and are designed to ensure the long-term survival of sea turtles by providing a dedicated fund supporting international conservation efforts.

“It’s a long-term job,” said Possardt. “In one human lifetime, you have to look for small victories. In the larger picture, all of those will begin to add up, and through the combined multinational efforts of governments, conservation organizations and the fishing industry, we can save the sea turtles. In the process, we will also create more sustainable marine ecosystems for humanity.”

For more information about the U.S. Fish and Wildlife Service, visit http://www.fws.gov

20 species of birds, sea mammals face extinction threat

Peninsula Online – Ssatish Kanady

doha • A total of 20 species of birds, fish and sea mammals are facing the extinction threat in Qatar, says the Sustainable Development report released by the General Secretariat for Development Planning (GSDP). “Qatar has a recorded 262 bird species and 1.9 per cent of them are facing extinction threat. Of the total 139 species of fish and sea mammals, 2.2 per cent are also facing the threat,” the report says. The environment indication section of the document also says that Qatar’s coastal water has a high rate of ammonia and nitrate concentration. The high concentration of these elements can cause excessive growth of plant planktons leading to a tilt in the balance of Qatar’s marine eco system.

Regarding the endangered species, the report says that the birds form 5 species while the fish and mammals are amounting to dozens. The document stressed the need for preserving and multiplying the numbers of the species. The document is optimistic that Qatar’s renewed efforts to protect the living ecosystem and the decision to expand the area of land, marine natural and coastal reserve will help combat the menace. The Islamic Shariah’s promotion on raising awareness of the importance of conserving living creatures and the enactment of environmental law regulating hunting will come to the rescue of endangered species.

Strict measures have also been introduced to prohibit trading in living species threatened with extinction listed in the appendices of the Convention of International Trading in Endangered Species (Cites). On the concentration of natural nutrient elements such as nitrogen and phosphorous in coastal waters, the data indicator shows a high concentration of ammonia , in general, in Qatari coastal waters, with concentration ranging between 63.33 and 185.1 in the area facing Mesaieed. “Causes of this high rate are flows rich in ammonia by some industrial enterprises”, the document said.

Nitrate concentration is also high in coastal waters facing Doha, reaching 144 microgrammes/litre in 2004. This high concentration is due to the biodegradation of some nitrogenous substances and their oxidation by bacteria into nitrates. “A high increase of the concentration of these elements can cause excessive growth of plant planktons and the ecological equilibrium in the area will be negatively affected. Some poisonous plant substances cause the death of large quantities of fish and huge numbers of marine animals will perish. Concentration of ammonia and nitrates in Qatari coastal waters is high when compared with the values recorded in some Arabian Gulf areas.” the environment indicator report said.

The environmental indicator also shows a decline in the quantity of underground water. Field measurements indicated a high salinity rate in the underground water. According to the report, underground water consumption rates are expected to fall in the next few years. “Qatar aims at reducing annual withdrawal of underground water, discovering feeding sources to upgrade its quality as well as search for substitute water resources, both conventional and non-conventional”, the document said.

Groups to Monitor Whales in Beaufort Sea

Associated Press - Dan Joling

ANCHORAGE, Alaska (AP) — Endangered humpback whales swam into the Beaufort Sea off Alaska’s northern coast this summer, far beyond their usual range, but federal officials monitoring the waters say it’s too soon to determine whether it’s a trend or an anomaly.

Environmental groups say the presence of humpbacks hundreds of miles north of their usual habitat likely is another sign of the effects of global warming and the shifting Arctic ecosystem. They are calling for more study of the endangered animals’ habits before industrial activity is allowed to expand off Alaska’s northern shores.

Robin Cacy, a spokeswoman for the federal Minerals Management Service, which oversees lease sales for offshore petroleum drilling in federal waters, confirmed that humpback whales were spotted in the Beaufort Sea east of Barrow, the northernmost community in the United States. Humpback whales were seen in the Chukchi Sea off Alaska’s northwest coast last year, she said.

Also, endangered fin whales were detected this summer by acoustic monitoring north of the Bering Strait in the Chukchi Sea, Cacy said. The fin whales were recorded as far north as Point Lay, a coastal Inupiat Eskimo village of 235 about 700 miles northwest of Anchorage.

Some of the whales were spotted by observers involved with the oil industry. Shell Exploration and Production and its contractors performed seismic work this summer in anticipation of bidding on leases. Lease sales are scheduled for 2008 in the Chukchi Sea and 2009 in the Beaufort Sea. Cacy said some whales also were spotted by observers involved with barge traffic.

No one was expecting humpbacks near the activity connected to Outer Continental Shelf lease sales, said Brad Smith, a protective resources biologist for the National Marine Fisheries Service.

“We expected those to be further south and west of the OCS planning areas,” Smith said. “We didn’t anticipate that they’d been encountered in any of the OCS exploration activity that we’re doing this year.”

Brendan Cummings, ocean programs director for the Center for Biological Diversity, said the sightings may be an indication of a recovering humpback population expanding its range or of desperate animals in search of food.

Other species that use the Chukchi Sea, from walrus congregating on Alaska’s northwest shore to gray whales seeking new feeding areas, are behaving differently because of climate change, he said.

“It looks like the populations are suffering from it,” he said. “All signs point to global warming. That would be the first suspect of why the whales are there.”

Deborah Williams, a former Department of Interior special assistant for Alaska, and now an advocate for finding solutions to climate change, said the presence of humpback and fin whales so far north has significant implications for the animals’ management and development.

“We now have even more compelling reasons to protect the Arctic Ocean and the species dramatically affected by climate change,” she said.

Sheela McLean, spokeswoman for the National Oceanic and Atmospheric Administration’s fisheries service in Juneau, said humpbacks range widely and have been spotted on the Russian part of the Chukchi Sea. However, humpbacks are not usually associated with pack ice, so sightings further north might be shifts in distribution caused by climate change, she said.

This year was a record low year for pack ice. The National Snow and Ice Data Center at the University of Colorado at Boulder in September recorded 1.65 million square miles of sea ice. That’s 39 percent below the long-term average from 1979 to 2000.

Gary Strasburg, a spokesman for the Minerals Management Service in Washington, D.C., said a sighting of an endangered species in a new area would not mean an immediate change in how the agency regulates petroleum exploration. The agency would determine whether the presence of humpbacks was a trend, and if so, determine the appropriate response, he said.

Federal laws allow a certain level of “harassment” of marine mammals, Smith said. Permits issued in 2007 for exposure of marine mammals to noise from seismic activities covered neither humpback nor fin whales, he said.

“They do, however, have authorization to harass other whales and marine mammals, which were expected to be encountered during the course of their seismic operations,” Smith said, including ringed seals, bearded seals, gray whales and bowhead whales.

Conditions imposed upon exploration for humpbacks may be no different than what’s in place now, Smith said. The sensitivity of bowhead whales, which remain close to sea ice and are hunted in limited numbers by Eskimo whalers, is considered equal to or greater than the sensitivity of humpbacks, he said.

Cummings does not agree with that assessment of humpbacks — or with the government’s protective measures in general.

“These are animals that are entirely dependent on sound,” he said of humpbacks.

Permits issued don’t take into account the federal government’s own research indicating how easily whales can be deflected from their intended paths. The noise could have consequences for whales’ feeding and energy expended feeding behavior, especially mothers migrating with their young.

“We don’t believe that permits issued to date in the Beaufort Sea comply with the spirit or the letter of the Marine Mammal Protection Act or the Endangered Species Act,” he said.

Humpback, fin and bowhead whales are all baleen whales. Humpback and fin whales feed on krill and plankton plus small, schooling fish such as herring or capelin.

Humpbacks are seasonal feeders, building up body fat reserves in the summer and migrating to warmer, subtropical areas during the winter breeding season.

Full-grown humpback whales average 42 feet long and weigh 25 tons. Females average 45 feet long and 35 tons.

Fin whales are even larger. The long, slender whales grow to nearly 88 feet, the second longest of the whales behind blue whales.

Mussels face extinction as oceans turn acidic

The Telegraph – Richard Gray

Prized as a luxury treat in the best restaurants and a staple food in the human diet for thousands of years, oysters and mussels are now being threatened by rising levels of carbon dioxide.

By the end of the century many popular seafood dishes will disappear from our tables as shellfish become increasingly scarce, scientists warn.

They have found that the build up of carbon dioxide in the atmosphere is causing the oceans to grow more acidic as increasing amounts of the gas dissolve in sea water.

This change is reducing the ability of shellfish to make their protective shells. By 2100 some waters are expected to be corrosive enough to cause the shells to dissolve completely, making it impossible for them to survive.

Marine biologists warn that this could have a devastating effect on the ocean environment, as other creatures that eat shellfish will find food increasingly scarce while corals, which make reefs, will also be unable to build their hard external skeletons.

Dr Carol Turley, from Plymouth Marine Laboratory, will tell a conference of doctors at the Royal Society of Medicine that climate change is likely to have a profound effect on human ability to use the oceans as a source of food.

Speaking ahead of the conference later this month, she said the fishing industry would struggle to find supplies of scallops, mussels and oysters for restaurant tables due to ocean acidification.

She said: “The oceans take up carbon dioxide as we produce more and more into the atmosphere. They have already taken up half of the carbon dioxide released into the atmosphere since the industrial revolution.

“The problem this causes has only really emerged very recently.

“Many shellfish use calcium carbonate to make their shells, but the more carbon dioxide in the ocean, the less carbonate is available to those organisms that use it.

“A lot of shellfish are an important food source for fish as well as humans. The impacts of shellfish disappearing could be massive.”

Shellfish produce their shells by absorbing calcium carbonate from the water and depositing it around their bodies. Carbon dioxide, however, produces an acid when it is dissolved in water that reduces the availability of calcium carbonate, causing shellfish to grow far more slowly.

Dr Turley explained that in colder seas around the poles, the reaction is more profound and the water may even act to dissolve the shells of shellfish.

Scientists had originally hoped that by dissolving excess carbon dioxide in the oceans it might be possible to reduce the effects of climate change on the planet, but oceanographers now fear the move could be devastating.

Mussels, clams, scallops and oysters are expected to be the worst-hit as the oceans grow more acidic. However prawns, crabs and lobsters will escape unharmed as they produce their shells in a different way.

Coral reefs will also be hit as the coral polyps use calcium carbonate to create the hard skeletons that provide shelter and some of the most diverse habitats in the oceans.

Climate change scientists warn that ocean acidification will add to the other impacts of global warming. Many species can only survive in tight bands of water temperature so as the seas heat up, fish will be forced to find cooler waters.

Ocean acidification is also expected to affect the ability of fish to fertilise eggs.

Around 150,000 tons of shellfish are caught by UK fishing vessels every year and it now accounts for around 40 per cent of the fishing industry’s catch as cod and haddock stocks have declined.

Dr Ian Totterdell, an ocean modeller at the Met Office’s Hadley Centre for Climate Research, said: “Carbon dioxide naturally dissolves in the oceans, but we have been tipping the balance by releasing more carbon dioxide into the atmosphere.

“For a long time this was seen as a good thing as it was helping to protect us from the full effects of greenhouse gases on the climate, but it now seems shellfish are suffering as a side effect.”

Fishes in Europe threatened

Reuters

GENEVA (Reuters) – More than a third of freshwater fish species in Europe face extinction due to overfishing, pollution and dams which have caused rivers to dry up, a scientific study said on Thursday.

The continent’s 522 freshwater fish species are under a much higher level of threat than birds or mammals, according to the study “Handbook of European Freshwater Fishes,” published in collaboration with the World Conservation Union (IUCN).

“With 200 fish species in Europe facing a high risk of going extinct, we must act now to avoid a tragedy,” said William Darwall, senior program officer at IUCN’s species program.

Twelve species are already extinct following a century of development which has had a devastating impact, the study said.

The European eel, which reproduces only once on average at around 20 years, is critically endangered, it said. The number of juvenile eels reaching European coasts has dropped dramatically in the past three decades.

The jarabugo, found in southwestern Spain and Portugal, is also endangered as its population has declined by more than 50 percent in the past 10 years.

“Large dams built for irrigation, flood control and power generation have had major impacts upon species in large rivers and have led to local extinction of numerous migratory species,” the Swiss-based IUCN said.

This has led to some rivers drying up in the summer months, a phenomenon which was “becoming more acute with the impacts of climatic changes,” it said.

Areas subject to the highest levels of threat include the lower reaches of the rivers Danube, Dniestr, Dniepr, Volga and Ural, the Balkan peninsula and southwestern Spain, it added.