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
Sport
wimbledonScot will face Ivo Karlovic next
Sport
football
News
Hillary Clinton comments on viral Humans of New York photo of gay teenager
Arts and Entertainment
The gang rape scene in the Royal Opera’s production of Gioachino Rossini’s Guillaume Tell has caused huge controversy
music
Have you tried new the Independent Digital Edition apps?
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Sales Administrator - Spanish Speaking

£17000 - £21000 per annum: Recruitment Genius: This is a fantastic opportunity...

Recruitment Genius: Sales Administrator - German Speaking

£17000 - £23000 per annum: Recruitment Genius: This is a fantastic opportunity...

Recruitment Genius: Sales Administrator - Japanese Speaking

£17000 - £23000 per annum: Recruitment Genius: If you are fluent in Japanese a...

Recruitment Genius: Graphic Designer - Immediate Start

£16000 - £25000 per annum: Recruitment Genius: This is a fantastic opportunity...

Day In a Page

Is this the future of flying: battery-powered planes made of plastic, and without flight decks?

Is this the future of flying?

Battery-powered planes made of plastic, and without flight decks
Isis are barbarians – but the Caliphate is a dream at the heart of all Muslim traditions

Isis are barbarians

but the Caliphate is an ancient Muslim ideal
The Brink's-Mat curse strikes again: three tons of stolen gold that brought only grief

Curse of Brink's Mat strikes again

Death of John 'Goldfinger' Palmer the latest killing related to 1983 heist
Greece debt crisis: 'The ministers talk to us about miracles' – why Greeks are cynical ahead of the bailout referendum

'The ministers talk to us about miracles'

Why Greeks are cynical ahead of the bailout referendum
Call of the wild: How science is learning to decode the way animals communicate

Call of the wild

How science is learning to decode the way animals communicate
Greece debt crisis: What happened to democracy when it’s a case of 'Vote Yes or else'?

'The economic collapse has happened. What is at risk now is democracy...'

If it doesn’t work in Europe, how is it supposed to work in India or the Middle East, asks Robert Fisk
The science of swearing: What lies behind the use of four-letter words?

The science of swearing

What lies behind the use of four-letter words?
The Real Stories of Migrant Britain: Clive fled from Zimbabwe - now it won't have him back

The Real Stories of Migrant Britain

Clive fled from Zimbabwe - now it won’t have him back
Africa on the menu: Three foodie friends want to popularise dishes from the continent

Africa on the menu

Three foodie friends want to popularise dishes from the hot new continent
Donna Karan is stepping down after 30 years - so who will fill the DKNY creator's boots?

Who will fill Donna Karan's boots?

The designer is stepping down as Chief Designer of DKNY after 30 years. Alexander Fury looks back at the career of 'America's Chanel'
10 best statement lightbulbs

10 best statement lightbulbs

Dare to bare with some out-of-the-ordinary illumination
Wimbledon 2015: Heather Watson - 'I had Serena's poster on my wall – now I'm playing her'

Heather Watson: 'I had Serena's poster on my wall – now I'm playing her'

Briton pumped up for dream meeting with world No 1
Wimbledon 2015: Nick Bollettieri - It's time for big John Isner to produce the goods to go with his thumping serve

Nick Bollettieri's Wimbledon Files

It's time for big John Isner to produce the goods to go with his thumping serve
Dustin Brown: Who is the tennis player who knocked Rafael Nadal out of Wimbeldon 2015?

Dustin Brown

Who is the German player that knocked Nadal out of Wimbeldon 2015?
Ashes 2015: Damien Martyn - 'England are fired up again, just like in 2005...'

Damien Martyn: 'England are fired up again, just like in 2005...'

Australian veteran of that Ashes series, believes the hosts' may become unstoppable if they win the first Test