Featured Research

from universities, journals, and other organizations

Wild rainbow trout critical to health of steelhead populations

Date:
January 31, 2011
Source:
Oregon State University
Summary:
Genetic research is showing that healthy steelhead runs in Pacific Northwest streams can depend heavily on the productivity of their stay-at-home counterparts, rainbow trout.

New research shows that a steelhead, such as the large fish in this image, is just one of the options for steelhead reproduction, along with other fish such as rainbow trout.
Credit: Photo by John McMillan

Genetic research is showing that healthy steelhead runs in Pacific Northwest streams can depend heavily on the productivity of their stay-at-home counterparts, rainbow trout.

Steelhead and rainbow trout look different, grow differently, and one heads off to sea while the other never leaves home. But the life histories and reproductive health of wild trout and steelhead are tightly linked and interdependent, more so than has been appreciated, a new Oregon State University study concludes.

The research could raise new challenges for fishery managers to pay equally close attention to the health, stability and habitat of wild rainbow trout, the researchers say, because healthy steelhead populations may require healthy trout populations.

In a field study in Hood River, Ore., researchers used DNA analysis to determine that up to 40 percent of the genes in returning steelhead came from wild rainbow trout, rather than other steelhead. And only 1 percent of the genes came from "residualized" hatchery fish -- fish that had stayed in the stream and mated, but not gone to sea as intended by the hatchery program.

"It used to be thought that coastal rainbow trout and steelhead were actually two different fish species, but we've known for some time that isn't true," said Mark Christie, an OSU postdoctoral research associate and expert in fish genetic analysis. "What's remarkable about these findings is not just that these are the same fish species, but the extent to which they interbreed, and how important wild trout are to the health of steelhead populations."

This research, just published in the journal Molecular Ecology, was based on a 15-year analysis of 12,725 steelhead from Oregon's Hood River, each of which was sampled to determine its genetic background and parentage. It was supported by funding from the Bonneville Power Administration.

The study reveals a complex picture of wild trout and steelhead intermingling as they reproduce. A steelhead might be produced by the spawning of two steelhead, two wild trout, or a returning steelhead and a trout.

Rainbow trout are small to moderate-sized fish in most rivers, but if that same fish migrates to the ocean it can return as a huge steelhead weighing 30 pounds or more, prized for sport fishing. Researchers still don't know exactly why some trout choose to go to the ocean and others don't, although they believe at least some part of the equation is genetic.

Studies of rainbow trout and steelhead have been undertaken, in part, to better understand the implications of hatcheries. Including all salmonid species, more than one billion hatchery salmon are released into Pacific Northwest streams each year. And because hatcheries produce fish that are less able to survive and successfully reproduce in the wild, there is concern about hatchery fish mating with wild fish.

"One implication of this study is that the genetic contribution by wild trout is diluting the input of genes from hatchery fish to the wild steelhead population," said Michael Blouin, an OSU professor of zoology and co-author on this study.

"The genetic influences of hatchery fish on wild steelhead populations are still a concern," Blouin said. "But the good news from the Hood River is that the hatchery genes are being diluted more than we thought, and thus may not be having as much impact on dragging down the fitness of the wild steelhead."

The genetic influence of wild rainbow trout, the scientists said, is roughly cutting in half the genetic input of hatchery fish that reproduce in the wild -- a mitigation of their impact that's of some importance.

The scientists cautioned that results from one river might not be representative of all steelhead populations. Nevertheless, Christie said, "The importance of trout in maintaining steelhead runs should not be underestimated.

"They can act as a healthy genetic reservoir and preserve reproductive populations during years when ocean conditions make steelhead survival very difficult," he said. "So a good way of looking at it is, whatever is good for wild rainbow trout is also good for steelhead."

Worth noting, the researchers said, is that most other salmonids, such as coho or chinook salmon, do not have this type of fall-back system to help produce fish with a higher capability of surviving. As such, they may be more vulnerable than steelhead to the concerns about genetic weaknesses produced by hatchery fish.


Story Source:

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


Journal Reference:

  1. Mark R. Christie, Melanie L. Marine, Michael S. Blouin. Who are the missing parents? Grandparentage analysis identifies multiple sources of gene flow into a wild population. Molecular Ecology, 2011; DOI: 10.1111/j.1365-294X.2010.04994.x

Cite This Page:

Oregon State University. "Wild rainbow trout critical to health of steelhead populations." ScienceDaily. ScienceDaily, 31 January 2011. <www.sciencedaily.com/releases/2011/01/110131133119.htm>.
Oregon State University. (2011, January 31). Wild rainbow trout critical to health of steelhead populations. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2011/01/110131133119.htm
Oregon State University. "Wild rainbow trout critical to health of steelhead populations." ScienceDaily. www.sciencedaily.com/releases/2011/01/110131133119.htm (accessed July 24, 2014).

Share This




More Health & Medicine News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Newsy (July 23, 2014) An 8-year-old boy helped his younger brother, who has a rare genetic condition that's confined him to a wheelchair, finish a triathlon. Video provided by Newsy
Powered by NewsLook.com
Thousands Who Can't Afford Medical Care Flock to Free US Clinic

Thousands Who Can't Afford Medical Care Flock to Free US Clinic

AFP (July 23, 2014) America may be the world’s richest country, but in terms of healthcare, the World Health Organisation ranks it 37th. Thousands turned out for a free clinic run by "Remote Area Medical" with a visit from the Governor of Virginia. Duration: 2:40 Video provided by AFP
Powered by NewsLook.com
Stone Fruit Listeria Scare Causes Sweeping Recall

Stone Fruit Listeria Scare Causes Sweeping Recall

Newsy (July 22, 2014) The Wawona Packing Company has issued a voluntary recall on the stone fruit it distributes due to a possible Listeria outbreak. Video provided by Newsy
Powered by NewsLook.com
Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Newsy (July 22, 2014) The 83 new genetic markers could open dozens of new avenues for schizophrenia treatment research. Video provided by Newsy
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:
from the past week

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