Featured Research

from universities, journals, and other organizations

Salmon And Trout Hatcheries Cause 'Stunning' Loss Of Reproduction

Date:
October 5, 2007
Source:
Oregon State University
Summary:
The rearing of steelhead trout in hatcheries causes a dramatic and unexpectedly fast drop in their ability to reproduce in the wild, a new study shows, and raises serious questions about the wisdom of historic hatchery practices.

Typical fish hatchery in the US. The rearing of steelhead trout in hatcheries can cause 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.
Credit: USGS

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.

Related Articles


The research, to be published 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 Oregon's Hood River.

"For fish to so quickly lose their ability to reproduce is stunning, it's 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 weren't 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."

This research was conducted through use of 15 years of DNA tracking technology of fish breeding in Hood River, a mountain stream that flows northward off Mount Hood into the Columbia River. DNA analysis with scales was done with about 15,000 fish since 1991.

This research has been supported by the Bonneville Power Administration and the Oregon Department of Fish and Wildlife.


Story Source:

The above story is based on materials provided by Oregon State University. Note: Materials may be edited for content and length.


Cite This Page:

Oregon State University. "Salmon And Trout Hatcheries Cause 'Stunning' Loss Of Reproduction." ScienceDaily. ScienceDaily, 5 October 2007. <www.sciencedaily.com/releases/2007/10/071004143128.htm>.
Oregon State University. (2007, October 5). Salmon And Trout Hatcheries Cause 'Stunning' Loss Of Reproduction. ScienceDaily. Retrieved January 25, 2015 from www.sciencedaily.com/releases/2007/10/071004143128.htm
Oregon State University. "Salmon And Trout Hatcheries Cause 'Stunning' Loss Of Reproduction." ScienceDaily. www.sciencedaily.com/releases/2007/10/071004143128.htm (accessed January 25, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, January 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Florida Might Legalize Black Bear Hunting

Florida Might Legalize Black Bear Hunting

Newsy (Jan. 24, 2015) A string of black bear attacks has Florida officials considering lifting the ban on hunting the animals to control their population. Video provided by Newsy
Powered by NewsLook.com
Ebola Killing Large Portion Of Ape Population

Ebola Killing Large Portion Of Ape Population

Newsy (Jan. 23, 2015) Experts estimate Ebola has wiped out one-third of the world&apos;s gorillas and chimpanzees. Video provided by Newsy
Powered by NewsLook.com
Controversy Shrouds Captive Killer Whale in Miami

Controversy Shrouds Captive Killer Whale in Miami

Reuters - Light News Video Online (Jan. 23, 2015) Activists hope the National Oceanic and Atmospheric Agency (NOAA) will label killer whales endangered, allowing lawyers to sue a Miami aquarium to release an orca into the wild after 44 years. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
‘Healthy’ Foods That Surprisingly Pack on Pounds

‘Healthy’ Foods That Surprisingly Pack on Pounds

Buzz60 (Jan. 23, 2015) Some &apos;healthy&apos; foods are actually fattening. Fitness and nutrition expert John Basedow (@JohnBasedow) shines a light on the sneaky foods like nuts, seeds, granola, trail mix, avocados, guacamole, olive oil, peanut butter, fruit juices and salads that are good for you...but not so much for your waistline. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins