Posts Tagged blufin tuna

Nov 21 2014

Surrogate sushi: Japan biotech for bluefin tuna

AP Business Writer

TATEYAMA, Japan (AP) – Of all the overfished fish in the seas, luscious, fatty bluefin tuna are among the most threatened. Marine scientist Goro Yamazaki, who is known in this seaside community as “Young Mr. Fish,” is working to ensure the species survives.

Yamazaki is fine-tuning a technology to use mackerel surrogates to spawn the bluefin, a process he hopes will enable fisheries to raise the huge, torpedo-shaped fish more quickly and at lower cost than conventional aquaculture. The aim: to relieve pressure on wild fish stocks while preserving vital genetic diversity.

Yamazaki, 48, grew up south of Tokyo in the ancient Buddhist capital of Kamakura, fishing and swimming at nearby beaches. His inspiration hit 15 years ago while he was out at sea during graduate studies at the Tokyo University of Marine Science and Technology, and a school of bluefin tuna streaked by.

“They swam just under the boat, and they were shining metallic blue. A beautiful animal,” Yamazaki said. “Before that, tuna was just an ingredient in sushi or sashimi, but that experience changed bluefin tuna into a wild animal to me.”

An animal, that like so many other species, is endangered due to soaring consumption and aggressive modern harvesting methods that have transformed the bluefin, also known as “honmaguro” and “kuromaguro,” from a delicacy into a commonly available, if pricey, option at any sushi bar.

This month, experts in charge of managing Atlantic bluefin met in Italy and raised the quota for catches of Atlantic bluefin tuna by 20 percent over three years. Stocks have recovered somewhat after a severe decline over the past two decades as fishermen harvested more to meet soaring demand, especially in Japan.

But virtually in tandem with that, the International Union for Conservation of Nature put Pacific bluefin tuna on its “Red List,” designating it as a species threatened by extinction.

About a quarter of all tuna are consumed by the Japanese, according to the United Nations Food and Agricultural Organization. They gobble up most – between 60 percent and 80 percent – of all bluefin. Rosy, fatty “chu-toro” from the upper part of bluefin bellies, is especially prized for sushi and sashimi.

Out at his seaside lab in Tateyama, on the far northern rim of Tokyo Bay, Yamazaki and other researchers are hoping their latest attempt to get mackerel to spawn bluefin will prove a success. An earlier attempt failed due to what he thinks was a problem with the water temperature.

Yamazaki’s technique involves extracting reproductive stem cells from the discarded guts of tuna shipped by cold delivery from fish farms and inserting them into mackerel fry so tiny they are barely visible.

The baby fish are put in an anesthetic solution and then transferred by dropper onto a slide under the microscope. Researcher Ryosuke Yazawa deftly inserts a minute glass needle into one’s body cavity to demonstrate.

Under the right conditions, the tuna stem cells migrate into the ovaries and testes of the mackerel. The team is now waiting to see if the mackerel, when mature, will spawn tuna, and if the tuna will survive. Following that, they could be released into the sea or farmed.

The research team has already succeeded in using surrogate technology to produce tiger puffer fish, the poisonous “fugu” used in sashimi and hotpot, using smaller grass puffer fish. It has produced trout spawned by salmon. Companies that import rare and tropical fish also are interested in the technology.

The method could help reduce pressure on wild populations, Yamazaki hopes, and also help ensure the greater genetic diversity needed to preserve various species.

Though he started out working in the field of genetic modification, Yamazaki emphasizes that his techniques involve only surrogate reproduction, not GM.

The main “tricks,” as he calls them, are using baby fish as future surrogates, because their immature immune systems will not reject the tuna cells, and relying on the natural tendency of the reproductive stem cells to mature and produce viable offspring. To simplify matters, the lab is using triploid, or sterile hybrid fish commonly bred at fish farms, that will not develop eggs or sperm of their own species.

Yamazaki expects his research to be useful for commercial purposes. Though researchers elsewhere have succeeded in breeding tuna in captivity, the process is costly and survival rates are low. Mackerel, less than a foot long when caught, are much easier to handle and keep in land-based tanks than tuna, which can grow to nearly the size of a small car and require far more food per fish. The mackerel also mature more quickly and spawn more frequently, if they are well fed and kept at the right temperature.

Not all experts favor such high-tech solutions for the bluefin.

Amanda Nickson, director of global tuna conservation for The Pew Charitable Trusts, said the partial recovery of Atlantic bluefin stocks shows that enforcement of catch limits, backed by threats of trade bans, can work.

Earlier this year, the multi-nation fisheries body that monitors most of the Pacific Ocean recommended limiting the catch of juvenile bluefin tuna to half the average level of 2002-2004. Scientists found that stocks of the species had dwindled to less than 4 percent of their original size. It also found that most fish caught were juveniles less than 3 years old, before they reach reproductive maturity.

The group set a 10-year target of rebuilding the population to 8 percent of its original size.

“As long as you don’t take too many, those populations can rebuild and rebuild fairly effectively,” she said.

Perhaps so, said Yamazaki, but over the centuries, humans have repeatedly over consumed resources, sometimes past the point of no return.

“Japanese people eat tuna from all over the world. We have to do something. That is the motivation for my research.”

5903779_G(AP Photo/Tokyo University of Marine Science and Technology, Goro Yamazaki)

5903780_G(AP Photo/Elaine Kurtenbach)

5903781_G(AP Photo/Elaine Kurtenbach)

5903782_G(AP Photo/Shizuo Kambayashi, File). FILE – In this Jan. 5, 2014 file photo, people watch a bluefin tuna laid in front of a sushi restaurant near Tsukiji fish market after the year’s celebratory first auction in Tokyo.

5903783_G(AP Photo/Elaine Kurtenbach)

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Nov 1 2014

Eastern Pacific bluefin tuna catch to be cut 40 percent to 3,300 tons

SEAFOODNEWS.COM [Jiji Press] – October 31, 2014posted with permission of Seafood News.

The Inter-American Tropical Tuna Commission, comprising a total of 21 countries and regions, has decided to tighten controls on bluefin tuna fishing in the eastern Pacific.

The decision was made at a special session of the commission in La Jolla, Calif., on Wednesday, according to Japanese officials.

Bluefin tuna catches in the ocean region will be reduced by 40 percent from the 2014 level to 3,300 tons in both 2015 and 2016.

The commission also set a nonbinding goal of cutting the proportion of young tuna weighing less than 30 kilograms in total catches to 50 percent.

The nonbinding goal was set as a compromise after Mexico opposed a Japanese proposal for halving annual catches of young tuna in and after 2015 from the average level between 2002 and 2004. In the central and western Pacific, including waters around Japan, the halving of young tuna catches has already been agreed.

Mexico has developed a tuna ranching sector dependent on capture of juvenile tuna used for growout.


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Aug 2 2013

A convenient truth: 90% of the tunas are gone!


Last week, I had the privilege of presiding over the defense of the Ph.D. dissertation of Maria José Juan-Jordá in La Coruña, Spain. Maria José is a bright young researcher and has already published several chapters of her dissertation in the peer-reviewed literature.

The first chapter in her dissertation(1) is the last in a series of peer-reviewed scientific papers that demonstrate that the combined biomass of large oceanic predators (mostly tunas) has not declined by 90% as stated in another scientific paper ten years ago.

The 90% decline figure came from an analysis published in 2003 which concluded that “large predatory fish biomass today is only about 10% of pre-industrial levels” [Myers and Worm, 2003(2)].  Those analyses relied heavily upon catch rates from a single fishing gear type (longline) and aggregated catch across species to estimate trends in “community biomass”. The paper quickly became high-profile in the tuna world. Many environmental groups embraced it as proof that all tunas, not just the bluefins, were in serious trouble. On the other hand, tuna scientists who were actually conducting stock assessments, especially for tropical tunas knew immediately that the 90% number was totally wrong.

Over the next few years, a number of peer reviewed publications(3,4,5,6,7,8) showed that the conclusions in Myers and Worm (2003) were fundamentally flawed. Two of the most important reasons for this are: The aggregation of data, and the use of data from a single fishing method. The end result is that the 90% decline is an overestimate. This process of rebuttal is a natural part of the way science develops. Sometimes scientists reach conclusions that are wrong, for whatever reason, and other scientists discover flaws and point to them. A paper, once published, is not necessarily immortal.

Nevertheless, the notion of 90% global demise of tuna populations is still out there. It is repeated in many consumer guides published by various environmental groups that want to influence market preferences. It also pops up elsewhere: Earlier this year, I visited the web site of a newly-formed commission that aims to improve governance of ocean resources, and I was surprised to see the 90% number mentioned there. A colleague of mine who also noticed it said he was “disappointed that one of the most rebutted fisheries paper of all time continues to raise its head.”

Read the full story here.

May 30 2011

Endangered species listing for Atlantic bluefin tuna not warranted

After an extensive scientific review, the NOAA announced last week that Atlantic bluefin tuna do not currently warrant species protection under the Endangered Species Act. 

The entire NOAA press release follows below:

After an extensive scientific review, NOAA announced today that Atlantic bluefin tuna currently do not warrant species protection under the Endangered Species Act.

NOAA has committed to revisit this decision by early 2013, when more information will be available about the effects of the Deepwater Horizon BP oil spill, as well as a new stock assessment from the scientific arm of the International Commission for the Conservation of Atlantic Tunas, the international body charged with the fish’s management and conservation.

NOAA is formally designating both the western Atlantic and eastern Atlantic and Mediterranean stocks of bluefin tuna as “species of concern” under the Endangered Species Act. This places the species on a watchlist for concerns about its status and threats to the species.

“NOAA is concerned about the status of bluefin tuna, including the potential effects of the Deepwater Horizon BP oil spill on the western stock of Atlantic bluefin, which spawns in the Gulf of Mexico,” said Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. “We will revisit the status of the species in early 2013 when we will have a new stock assessment and information from the Natural Resource Damage Assessment of the oil spill. We will also take action in the interim if new information indicates the need for greater protection.”

NOAA’s status review, released with today’s decision and peer-reviewed by The Center for Independent Experts, indicates that based on the best available information and assuming  countries comply with the bluefin tuna fishing quotas established by ICCAT, both the western and eastern Atlantic stocks are not likely to become extinct.

The status review team also looked at the best available information on the potential effects of the 2010 Deepwater Horizon BP oil spill on the future abundance of the western stock of bluefin tuna and found that it did not substantially alter the results of the extinction risk analysis.  While the NOAA team found that the presently available information did not favor listing, it also recognized the need to continue to monitor the potential long-term effects of the spill on bluefin tuna and the overall ecosystem. New scientific information is expected in a 2012 bluefin tuna stock assessment and as part of the Natural Resources Damage Assessment of the Deepwater Horizon BP oil spill.

“Based on careful scientific review, we have decided the best way to ensure the long-term sustainability of bluefin tuna is through international cooperation and strong domestic fishery management,” said Eric Schwaab, assistant NOAA administrator for NOAA’s Fisheries Service. “The United States will continue to be a leader in advocating science-based quotas at ICCAT, full compliance with these quotas and other management measures to ensure the long-term viability of this and other important fish stocks.”

NOAA conducted the status review of Atlantic bluefin after determining on Sept. 21, 2010, that a petition for listing under the ESA from a national environmental organization warranted a scientific status review.

To read the status review report on Atlantic bluefin tuna, the federal register notice and other information on bluefin tuna, please go to:

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