Hatchery salmon could spell trouble for their wild-born cousins by spreading genetic traits that impede survival, according to an article appearing in the current issue of the journal Science. The authors of the article found that Chinook salmon raised in a Canadian commercial hatchery laid significantly smaller eggs within four generations than wild salmon. In the wild, hatchlings from smaller eggs are less likely to survive. The findings add fuel to the argument that hatchery fish undermine the genetic vigor of wild populations; they also call into question the wisdom of using of hatcheries to rebuild the Northwest’s troubled salmon runs. Currently, hatcheries release about 200 million young salmon and steelhead into the wild every year in the Columbia River Basin alone.