From
www.sfgate.com (San Francisco Chronicle)
Sex-Change Salmon Called Cause for Alarm
Scientists fear for survival of species as males change to females in large numbers
Kim Murphy, Los Angeles Times
Seattle — Four-fifths of the female salmon spawning in the last free-flowing reach of the Columbia River apparently began life as males, raising troubling new questions about the survival of the Pacific Northwest’s signature fish species.
In a study that could provide ammunition in the battle over the massive hydropower dams that traverse the Columbia and Snake rivers, researchers at the University of Idaho and Washington State University found significant sex reversals in the fall chinook salmon that spawn on the Columbia’s Hanford Reach in central Washington.
The research is unsettling because salmon runs in the Hanford Reach — where the Columbia passes relatively unbridled through the vast Hanford nuclear reservation — are the healthiest in a region where many are on the brink of collapse.
The cause of the embryonic gender shift is unknown, but there are suspects. Environmental estrogens are one possibility. These are the chemical byproducts, potentially traceable to pesticides and industrial runoff, that have been linked to issues like early puberty and infant mortality in humans.
The other potential factor is the hydropower dams, which produce temperature fluctuations in the river of the kind known to cause gender modifications in fish.
If this is the case, it could add fuel to the debate over breaching dams in the West to save the region’s disappearing salmon runs. The Clinton administration is scheduled to release its final recommendations on that issue tomorrow.
One possible culprit — radiation from the Hanford reservation — has been discounted. The amount of radioactivity known to be going into the river is too small to have produced these kinds of changes, the study’s authors said.
Researchers cautioned that it is too early to draw conclusions from the study, which examined salmon in a single year and did not look at the effects of the gender shifts on the overall salmon population.
“I think maybe what this points out is there’s a whole lot we don’t know or understand right now,” said Gary Thorgaard, biology professor at Washington State and co-author of the study.
Both Thorgaard and James Nagler, a University of Idaho zoology professor, said there may be worrisome implications if the gender-altered fish produce generations that skew the population too heavily .
“Unfortunately, I can’t put this in a positive light,” Nagler said. “But we can’t really say anything relative to whether this could be a major factor (in the decline of salmon populations).”
Using a genetic test developed by British Columbia fisheries scientist Bob Devlin — who previously has documented gender shifts in fish — the salmon researchers were able to identify chromosomes in the fish after they had spawned and died.
“We have found that a majority of the female chinook salmon sampled carry a genetic marker that is found only in male salmon. The best explanation for these results is that these females have been sex reversed and are in fact male (in origin),” Nagler said.
There were no similar reversals in hatchery salmon that spawned near the Hanford Reach but had been hatched in well water — indicating that whatever caused the phenomenon was likely in the river water while the fish were developing in their eggs or shortly after hatching.
“These results may explain in part the difficulties some salmon have had reproducing in the Columbia River basin,” Nagler said.
Fish have the same chromosomal sex composition as any other species: females have two X chromosomes and males have an X and a Y.
While normal females will produce nothing but X-chromosome eggs, leaving male fish to determine the sex of the offspring, the sex-reversed females will produce half X-eggs and half Y-eggs. Y-eggs that are fertilized by Y- chromosome sperm will produce a YY-chromosome “super male” fish.
Indeed, this may already have happened, the researchers said.
“Whether this kind of fish is viable, that’s a big question,” Nagler said. “But if they do survive and they were to return in appreciable numbers to spawn, the scenario is we would have an increase in the number of males in the population because all the offspring of this fish would be male.”
Over a period of years, this could skew the fish population so far that reproduction rates would fall, the researchers said.
http://www.sfgate.com/cgi-bin/articl...20/MN80877.DTL
Just when you've thouoght you've seen it all.
Re: Sex-changed Salmon Cause for Alarm
Halloween is over O's, so you can take that dress off now. Well while you have it on, sing us some show tunes 
and seems to have found it's way up here....I think there is very little chance of it reproducing though 
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