Research on Oregon’s Hood River steelhead population suggests a bit of good news may be in the offing. Wild trout inhabiting the river are the source of 40% of the genetic makeup of its steelhead brethren, which is neatly offsetting the “watering down” of genetic makeup due to hatchery fish.

The trout and steelhead are the same species, interbreeding between the two being commonplace.

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.

– via PhysOrg.com

No mention was made whether additional complications arise from hatchery steelhead and hatchery trout being planted in the same watershed, and whether that would prove an additional source of dilution.

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.

Given the research covers a 15 year span and analysis of 12,000 steelhead, it’s fairly compelling. As scientists still cannot explain why one fish heads for saltwater and another doesn’t, it’s nice to know that as we pull down some of these old irrigation dams that are no longer needed, one or more small tributaries might contain remnants of the original strain trout – and therefore the original strain of steelhead, once thought extinct.

Makes for an unusual management issue. Many scientists are already on record that trout and steelhead are the same fish, and given that its no longer two distinct species how can you persist separate regulations for each? It would seem a canny lawyer could argue a 10 fish limit, 20 in possession held for the larger oceangoing variant as well as those pumped into the water at the Bridge Pool …