Salmon gives birth to trout in scientific leap that gives hope to endangered fish

A A A

Biology textbooks will never quite be the same again. Scientists have altered the reproductive organs of salmon so that they produce trout offspring.

A "germ" tissue from young trout was put into young salmon so that when the salmon became sexually mature they produced the sperm and eggs of trout. In a study published today in the journal Nature, the researchers report that they have successfully used the technique to breed healthy rainbow trout from salmon parents.

The scientists, led by Yutaka Takeuchi of the Tokyo University of Marine Science and Technology, said that the development could help many of the world's endangered species of fish. Dr Takeuchi said tissue transplants from one endangered species to a related but more common species that is easier to rear in captivity could help to boost the wild populations of threatened or commercially valuable fish.

"The seed production for a species with a large body size and longer generation time could be carried out in surrogate parents with a smaller body size and shorter generation time," Dr Takeuchi said.

The technique relies on transplants of "primordial germ cells", which are the specialised tissues of embryonic fish that eventually develop into the gonads, the sex organs of adults that produce the sperm and eggs. Dr Takeuchi and his colleagues took primordial germ cells from an embryonic North American rainbow trout and transplanted them into the embryos of the masu salmon, which is only found in east Asia. Although the two species are related - they both belong to a group known as the salmonids - they have been separated by at least eight million years of evolutionary history.

"The most striking biological difference between them is that rainbow trout are able to spawn several times during their lives, whereas masu salmon die after their first spawning," the researchers write in Nature.

When the salmon in the experiment grew into adults, some of them produced sex cells - sperm or eggs - from both species. The scientists went on to show that these salmon could produce healthy, viable trout offspring. "It is the first time in animals that the primordial germ cell transplantation experiment has worked on the trans-species level and showed the expected ultimate success, namely the production of live offspring," Dr Takeuchi said.

The findings have important commercial implications, because some of the rarest fish in the world, such as the bluefin tuna, are those that are being hunted to extinction.

"If primordial germ cells of bluefin tuna could be transplanted into mackerel, the surrogate mackerel would produce mature eggs and sperm derived from the donor tuna in a short period and in a small facility. Therefore, our technique may help to feed the world's sushi habit," Dr Takeuchi said.

In addition to helping endangered species and boosting the number of valuable fish such as the bluefin tuna, the research raises the possibility of producing expensive sturgeon caviar in the bodies of related but more common species which could be reared on fish farms.

Simon Davies, a fish biologist at the University of Plymouth, first heard of the study at a scientific conference in Hawaii in March where the Japanese scientists presented their results. "When I saw this research I said, 'My God this is really interesting'. I came away very stunned by the quality of the science. In the right hands it could be very beneficial," Dr Davies said.

Professor Gordon Reid, director of Chester Zoo and a leading fish specialist, was equally impressed by the Tokyo team's ability to transplant viable germ tissue from one species to another. "It does sound interesting because one could imagine in the area of declining populations of fish when one species is threatened you can salvage that species by utilising a more common species," he said.

Freezing the sperm of endangered fish has had limited success and freezing eggs has been even more problematical. Embryonic germ cells are easy to freeze so they could provide an answer to the problem, Professor Reid said.

However, the idea of using tissue transplants between fish species as a way of preserving endangered animals in the wild is a simplistic solution, warned Professor John Sumpter, a fish biologist at Brunel University.

"They are trying to sell this on the grounds of helping to preserve endangered species, but it strikes me as a hi-tech solution," he said. "The problem is not going to be addressed by this solution. The problem is one of habitat loss, over-fishing, and possibly climate change and pollution. These are what need to be addressed."

Suggested Topics
News
Denny Miller in 1959 remake of Tarzan, the Ape Man
people
Arts and Entertainment
Cheryl despairs during the arena auditions
tvX Factor review: Drama as Cheryl and Simon spar over girl band

News
Piers Morgan tells Scots they might not have to suffer living on the same island as him if they vote ‘No’ to Scottish Independence
news
News
i100Exclusive interview with the British analyst who helped expose Bashar al-Assad's use of Sarin gas
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
Sport
Angel Di Maria celebrates his first goal for Manchester United against QPR
Football4-0 victory is team's first win under new manager Louis van Gaal
Arts and Entertainment
art
News
newsIn short, yes
Arts and Entertainment
Rob James-Collier, who plays under-butler Thomas Barrow, admitted to suffering sleepless nights over the Series 5 script
tv'Thomas comes right up to the abyss', says the actor
Arts and Entertainment
Calvin Harris claimed the top spot in this week's single charts
music
Sport
BoxingVideo: The incident happened in the very same ring as Tyson-Holyfield II 17 years ago
News
Groundskeeper Willie has backed Scottish independence in a new video
people
Arts and Entertainment
The Doctor poses the question of whether we are every truly alone in 'Listen'
tvReview: Possibly Steven Moffat's most terrifying episode to date
News
i100
Life and Style
Cara Delevigne at the TopShop Unique show during London Fashion Week
fashion
News
The life-sized tribute to Amy Winehouse was designed by Scott Eaton and was erected at the Stables Market in Camden
peopleBut quite what the singer would have made of her new statue...
Sport
England's Andy Sullivan poses with his trophy and an astronaut after winning a trip to space
sport
News
peopleThe actress has agreed to host the Met Gala Ball - but not until 2015
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Teaching Assistant for KS1 & KS2 Huddersfield

£50 - £65 per day: Randstad Education Leeds: We are looking for flexible and i...

Teaching Assistant for KS1 & KS2 Huddersfield

£50 - £65 per annum: Randstad Education Leeds: We are looking for flexible and...

Primary Teaching Supply

£130 - £160 per day: Randstad Education Leeds: Qualified KS2 Supply Teacher r...

Year 1/2 Teacher

£130 - £160 per day: Randstad Education Leeds: Qualified KS1 Teacher required,...

Day In a Page

These Iranian-controlled Shia militias used to specialise in killing American soldiers. Now they are fighting Isis, backed up by US airstrikes

Widespread fear of Isis is producing strange bedfellows

Iranian-controlled Shia militias that used to kill American soldiers are now fighting Isis, helped by US airstrikes
Topshop goes part Athena poster, part last spring Prada

Topshop goes part Athena poster, part last spring Prada

Shoppers don't come to Topshop for the unique
How to make a Lego masterpiece

How to make a Lego masterpiece

Toy breaks out of the nursery and heads for the gallery
Meet the ‘Endies’ – city dwellers who are too poor to have fun

Meet the ‘Endies’ – city dwellers who are too poor to have fun

Urbanites are cursed with an acronym pointing to Employed but No Disposable Income or Savings
Paisley’s decision to make peace with IRA enemies might remind the Arabs of Sadat

Ian Paisley’s decision to make peace with his IRA enemies

His Save Ulster from Sodomy campaign would surely have been supported by many a Sunni imam
'She was a singer, a superstar, an addict, but to me, her mother, she is simply Amy'

'She was a singer, a superstar, an addict, but to me, her mother, she is simply Amy'

Exclusive extract from Janis Winehouse's poignant new memoir
Is this the role to win Cumberbatch an Oscar?

Is this the role to win Cumberbatch an Oscar?

The Imitation Game, film review
England and Roy Hodgson take a joint step towards redemption in Basel

England and Hodgson take a joint step towards redemption

Welbeck double puts England on the road to Euro 2016
Relatives fight over Vivian Maier’s rare photos

Relatives fight over Vivian Maier’s rare photos

Pictures removed from public view as courts decide ownership
‘Fashion has to be fun. It’s a big business, not a cure for cancer’

‘Fashion has to be fun. It’s a big business, not a cure for cancer’

Donatella Versace at New York Fashion Week
The fall of Rome? Cash-strapped Italy accused of selling its soul to the highest bidder

The fall of Rome?

Italy's fears that corporate-sponsored restoration projects will lead to the Disneyfication of its cultural heritage
Glasgow girl made good

Glasgow girl made good

Kelly Macdonald was a waitress when she made Trainspotting. Now she’s taking Manhattan
Sequins ahoy as Strictly Come Dancing takes to the floor once more

Sequins ahoy as Strictly takes to the floor once more

Judy Murray, Frankie Bridge and co paired with dance partners
Wearable trainers and other sporty looks

Wearable trainers and other sporty looks

Alexander Wang pumps it up at New York Fashion Week
The landscape of my imagination

The landscape of my imagination

Author Kate Mosse on the place that taught her to tell stories