The metal parts used to construct fish hatcheries, such as such as iron pipes and steel rebar, may be adversely affecting the navigation abilities of the fish the facilities were intended to help.

That's the verdict of a new study from Oregon State University, which determined exposure to iron and steel distorts the magnetic fields used by fish like young steelhead trout to get their directional bearings during migration.

Findings of the study have been published in the journal Biology Letters.

"The better fish navigate, the higher their survival rate," said study lead Nathan Putman, a postdoctoral researcher in the Department of Fisheries and Wildlife who conducted the research at the Oregon Hatchery Research Center in the Alsea River basin last year. "When their magnetic field is altered, the fish get confused."

Putnam's team deduced that subtle differences in the magnetic environment within hatcheries might explain why some hatchery fish do better than others after being released into the wild. So, finding a way to stabilizing magnetic fields by constructing hatcheries with alternate, non-magnetic materials, could be one way to produce better yields of fish, he said.

Scientists for decades have studied how salmon find their way across enormous area of ocean.

In 2013, Putman and other researchers found a correlation between the oceanic migration patterns of salmon and the drift of the Earth's magnetic field.

Then, earlier this year, through experiments at the Oregon Hatchery Research Center, the researchers confirmed the ability of salmon to navigate using magnetic fields.

For the latest research, hundreds of juvenile Chinook salmon were exposed to different magnetic fields that exist at the latitudinal extremes of their oceanic range -- and the fish responded to the simulated magnetic displacements by swimming in the direction that they perceived would take them to their marine feeding grounds.

The research showed fish indeed possess a natural ability to figure out where they are and which way to swim, depending on the magnetic fields they sense.

Putman explained he and his colleagues repeated the magnetic field experiment with steelhead trout and achieved similar results. Then the testing was expanded to determine if changes to the magnetic field in which fish were reared would affect their map sense, which it did.

Putman said more research is needed to determine exactly what magnetic disorientation caused to fishery materials ultimately means.

The loss of their map sense could be temporary, and able to be recalibrated after a period of time; likewise, it might be found there's a critical window in which the fish's map sense is imprinted, and if they are exposed to altered magnetic fields during that period of development, they could remain confused forever.

"There is evidence in other animals, especially in birds, that either is possible," said Putman, who now works for the National Oceanic and Atmospheric Administration. "We don't know enough about fish yet to know which is which."

The situation, he added, is "not a hopeless problem... you can fix these kinds of things. Retrofitting hatcheries with non-magnetic materials might be worth doing if it leads to making better fish."