SACRAMENTO -- A federal judge on Monday upheld protections for wild steelhead trout in California rivers, rejecting an argument by forestry groups that said the success of hatchery-raised steelhead has made the population sufficiently robust.
U.S. District Court Judge Oliver Wanger in Fresno disagreed. He said hatchery-raised fish are no substitute for wild steelhead.
While science shows that hatchery fish can be beneficial, they also can be detrimental to wild steelhead, Wanger wrote in his 168-page ruling.
Steelhead are listed as threatened or endangered in different parts of California.
In a related claim, the judge rejected a bid by Central Valley farmers to remove steelhead trout from the federal Endangered Species Act. The farmers pointed to an abundance of resident rainbow trout, steelhead that do not migrate to the ocean.
The Modesto Irrigation District had argued that rainbow trout are essentially the same species as wild steelhead. Wanger agreed with federal wildlife scientists, who have said wild steelhead are distinct and indispensable to the survival of the species.
The rulings signify another victory for federal wildlife agencies and the fishing and conservation groups that had intervened in the cases.
It is the third instance in two years in which a federal court has rejected arguments that hatchery fish ought to be counted as part of salmon or steelhead populations, said Steve Mashuda, an attorney at Earthjustice, a nonprofit group that represented the conservation and fishing groups.
Studies have shown that while wild and hatchery fish in a river may be genetically the same, they have behavioral differences that make wild fish more successful at surviving. Hatcheries can boost overall numbers of fish in a stream, but the fish they release also have poor reproduction rates and can compete with wild fish for food and mates. In some cases, they can hurt the sustainability of wild fish stocks, scientists have found.
An MID representative could not reached for comment.