Navigation Links
Salmonid hatcheries cause 'stunning' loss of reproduction

CORVALLIS, Ore. The rearing of steelhead trout in hatcheries causes a dramatic and unexpectedly fast drop in their ability to reproduce in the wild, a new Oregon State University study shows, and raises serious questions about the wisdom of historic hatchery practices.

The research, to be published Friday in the journal Science, demonstrates for the first time that the reproductive success of steelhead trout, an important salmonid species, can drop by close to 40 percent per captive-reared generation. The study reflects data from experiments in Oregons Hood River.

For fish to so quickly lose their ability to reproduce is stunning, its just remarkable, said Michael Blouin, an OSU associate professor of zoology. We were not surprised at the type of effect but at the speed. We thought it would be more gradual. If it werent our own data I would have difficulty believing the results.

Fish reared in a hatchery for two generations had around half the reproductive fitness of fish reared for a single generation. The effects appear to be genetic, scientists said, and probably result from evolutionary pressures that quickly select for characteristics that are favored in the safe, placid world of the hatchery, but not in the comparatively hostile natural environment.

Among other things, this study proves with no doubt that wild fish and hatchery fish are not the same, despite their appearances, said Michael Blouin, an OSU associate professor of zoology. Some have suggested that hatchery and wild fish are equivalent, but these data really put the final nail in the coffin of that argument.

Even a few generations of domestication may have significant negative effects, and repeated use of captive-reared parents to supplement wild populations should be carefully reconsidered, the scientists said in their report.

Traditionally, salmon and steelhead hatcheries obtained their brood stock and eggs from fish that were repeatedly bred in hatcheries they tended to be more docile, adapted well to surface feeding, and they thrived and survived at an 85-95 percent level in the safe hatchery environment.

More recently, some supplementation hatchery operations have moved to the use of wild fish for their brood stock, on the theory that their offspring would retain more ability to survive and reproduce in the wild, and perhaps help rebuild threatened populations.

What happens to wild populations when they interbreed with hatchery fish still remains an open question, Blouin said. But there is good reason to be worried.

Earlier work by researchers from OSU and the Oregon Department of Fish and Wildlife had suggested that first-generation hatchery fish from wild brood stock probably were not a concern, and indeed could provide a short-term boost to a wild population. But the newest findings call even that conclusion into question, he said.

The problem is in the second and subsequent generations, Blouin said. There is now no question that using fish of hatchery ancestry to produce more hatchery fish quickly results in stocks that perform poorly in nature.

Evolution can rapidly select for fish of certain types, experts say, because of the huge numbers of eggs and smolts produced and the relatively few fish that survive to adulthood. About 10,000 eggs can eventually turn into fewer than 100 adults, Blouin said, and these are genetically selected for whatever characteristics favored their survival. Offspring that inherit traits favored in hatchery fish can be at a serious disadvantage in the wild where they face risks such as an uncertain food supply and many predators eager to eat them.

Because of the intense pressures of natural selection, Blouin said, salmon and steelhead populations would probably quickly revert to their natural state once hatchery fish were removed.

However, just removing hatchery fish may not ensure the survival of wild populations. Studies such as this consider only the genetic background of fish and the effects of hatchery selection on those genetics, and not other issues that may also affect salmon or steelhead fisheries, such as pollution, stream degradation or climate change.

Blouin cautioned that these data should not be used as an indictment of all hatchery programs.

Hatcheries can have a place in fisheries management, he said. The key issue is how to minimize their impacts on wild populations.


Contact: Michael Blouin
Oregon State University

Related biology news :

1. Dysentery uses sword and shield to cause infection
2. Scientists detect probable genetic cause of some Parkinsons disease cases
3. BRCA1 causes ovarian cancer through indirect, biochemical route
4. Scientists decipher genome of fungus that can cause life-threatening infections
5. Researchers discover molecule that causes secondary stroke
6. UF Researchers Map Bacterial Proteins That Cause Tooth Loss
7. Molecule that usually protects infection-fighting cells may cause plaque deposits inside arteries
8. NASA study finds snow melt causes large ocean plant blooms
9. New Estimates For The Causes Of Child Deaths Worldwide
10. Emergence of cancer as major cause of childhood death in developing countries is not being adequately addressed
11. UNC launches study of liver injury caused by drugs
Post Your Comments:
(Date:11/19/2015)... 2015  Based on its in-depth analysis of the ... with the 2015 Global Frost & Sullivan Award for ... presents this award to the company that has developed ... of the market it serves. The award recognizes the ... on customer base demands, the overall impact it has ...
(Date:11/18/2015)... 18, 2015  As new scientific discoveries deepen our ... other healthcare providers face challenges in better using that ... In addition, as more children continue to survive pediatric ... and old age. John M. Maris, M.D ... of Philadelphia (CHOP) . --> John ...
(Date:11/17/2015)... 17, 2015 Paris from ... --> Paris from 17 th until ... biometrics innovation leader, has invented the first combined scanner in ... same scanning surface. Until now two different scanners were required: ... can capture both on the same surface. This innovation ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... , Nov. 24, 2015  Clintrax Global, Inc., a worldwide ... Carolina , today announced that the company has set a ... a 391% quarter on quarter growth posted for Q3 of 2014 ... and Mexico , with the establishment of ... December 2015. --> United Kingdom and ...
(Date:11/24/2015)... ... ... The Academy of Model Aeronautics (AMA), led by its Executive Council, has ... Prix, to represent the First–Person View (FPV) racing community. , FPV racing has exploded ... of racing and several new model aviation pilots have joined the community because of ...
(Date:11/24/2015)... Ltd. (OTCQB: TIKRF) today announced that its Annual General Meeting of Shareholders ... Israel time, at the law offices of Goldfarb Seligman ... Floor, Tel Aviv, Israel . ... to the Board of Directors; , election of Liat ... an amendment to certain terms of options granted to our Chief Executive ...
(Date:11/24/2015)... ... 2015 , ... In harsh industrial processes, the safety of ... can represent a weak spot where leaking process media is a possible hazard. ... , which are designed to tolerate extreme process conditions. They combine rugged design ...
Breaking Biology Technology: