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
Have you tried new the Independent Digital Edition apps?
Arts and Entertainment
Buttoned up: Ryan Reynolds with Helen Mirren in ‘Woman in Gold’
filmFor every box-office smash in his Hollywood career, there's always been a misconceived let-down. Now he says it's time for a reboot
News
people
News
Actress Julianne Moore wins the Best Actress in a Leading Role Award for 'Still Alice' during the 87th Annual Academy Awards in Hollywood, California
people
Sport
Ross Barkley
footballPaul Scholes says it's time for the Everton playmaker to step up and seize the England No 10 shirt
News
'We will fix it': mice in the 1970s children’s programme Bagpuss
science
Life and Style
2 Karl Lagerfeld and Choupette
fashion
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Customer Service Executive

£18000 - £22000 per annum: Recruitment Genius: This is an exciting opportunity...

Recruitment Genius: Retail Buyer / Ecommerce Buyer

£30000 - £35000 per annum: Recruitment Genius: Working closely with the market...

Recruitment Genius: Sales Executive - CAD Software Solutions Sales

£20000 - £50000 per annum: Recruitment Genius: A reputable company, famed for ...

Ashdown Group: Client Accountant Team Manager - Reading

Negotiable: Ashdown Group: The Ashdown Group has been engaged by a highly resp...

Day In a Page

War with Isis: Iraq declares victory in the battle for Tikrit - but militants make make ominous advances in neighbouring Syria's capital

War with Isis

Iraq declares victory in the battle for Tikrit - but militants make make ominous advances in neighbouring Syria
Scientists develop mechanical spring-loaded leg brace to improve walking

A spring in your step?

Scientists develop mechanical leg brace to help take a load off
Peter Ackroyd on Alfred Hitchcock: How London shaped the director's art and obsessions

Peter Ackroyd on Alfred Hitchcock

Ackroyd has devoted his literary career to chronicling the capital and its characters. He tells John Walsh why he chose the master of suspense as his latest subject
Ryan Reynolds interview: The actor is branching out with Nazi art-theft drama Woman in Gold

Ryan Reynolds branches out in Woman in Gold

For every box-office smash in Ryan Reynolds' Hollywood career, there's always been a misconceived let-down. It's time for a rethink and a reboot, the actor tells James Mottram
Why Robin Williams safeguarded himself against a morbid trend in advertising

Stars safeguard against morbid advertising

As film-makers and advertisers make increasing posthumous use of celebrities' images, some stars are finding new ways of ensuring that they rest in peace
The UK horticulture industry is facing a skills crisis - but Great Dixter aims to change all that

UK horticulture industry facing skills crisis

Great Dixter manor house in East Sussex is encouraging people to work in the industry by offering three scholarships a year to students, as well as generous placements
Hack Circus aims to turn the rule-abiding approach of TED talks on its head

Hack Circus: Technology, art and learning

Hack Circus aims to turn the rule-abiding approach of TED talks on its head. Rhodri Marsden meets mistress of ceremonies Leila Johnston
Sevenoaks is split over much-delayed decision on controversial grammar school annexe

Sevenoaks split over grammar school annexe

If Weald of Kent Grammar School is given the go-ahead for an annexe in leafy Sevenoaks, it will be the first selective state school to open in 50 years
10 best compact cameras

A look through the lens: 10 best compact cameras

If your smartphone won’t quite cut it, it’s time to invest in a new portable gadget
Paul Scholes column: Ross Barkley played well against Italy but he must build on that. His time to step up and seize that England No 10 shirt is now

Paul Scholes column

Ross Barkley played well against Italy but he must build on that. His time to step up and seize that England No 10 shirt is now
Why Michael Carrick is still proving an enigma for England

Why Carrick is still proving an enigma for England

Manchester United's talented midfielder has played international football for almost 14 years yet, frustratingly, has won only 32 caps, says Sam Wallace
Tracey Neville: The netball coach who is just as busy as her brothers, Gary and Phil

Tracey Neville is just as busy as her brothers, Gary and Phil

The former player on how she is finding time to coach both Manchester Thunder in the Superleague and England in this year's World Cup
General Election 2015: The masterminds behind the scenes

The masterminds behind the election

How do you get your party leader to embrace a message and then stick to it? By employing these people
Machine Gun America: The amusement park where teenagers go to shoot a huge range of automatic weapons

Machine Gun America

The amusement park where teenagers go to shoot a huge range of automatic weapons
The ethics of pet food: Why are we are so selective in how we show animals our love?

The ethics of pet food

Why are we are so selective in how we show animals our love?