A group of young people are busy all week repainting messages on Rogue River boat ramps that aim to keep invasive fish from Oregon's waterways.
"No live fish in, no live fish out" is being repainted 19 times, mostly on the Rogue River from Chinook Park above Grants Pass to Grave Creek 30 miles downstream.
Lake Selmac's boat ramp will get the same refresh. The work is being done by the Oregon Youth Conservation Corps.
While dumping fish from other places happens more frequently in lakes and reservoirs, signing boat ramps on the river is all part of the larger message, said Dan Van Dyke of the Oregon Department of Fish and Wildlife.
"I'm just fed up with people illegally moving fish around," said Van Dyke, district biologist based in Central Point. "Not only are there fishery impacts, there's the chance people could bring in a whole host of aquatic species."
The list of dangerous invasives is long, but topping the charts are likely quagga and zebra mussels, which have found their way to Oregon but are so far not found in the Rogue watershed.
The Department of Fish and Wildlife has five boat inspection stations, including one south of Ashland on Interstate 5. All vehicles pulling watercraft are required to stop for an inspection.
If a boat is found to be contaminated with quagga or zebra mussels, New Zealand mudsnails, aquatic plants or other aquatic invaders, it will be decontaminated on site by the watercraft inspection team.
There is no penalty or cost for the boat owner if their boat is found to contain invasive species.
"Prevention is the only way to keep aquatic invasive species out of Oregon's waters," said Rick Boatner, Fish and Wildlife invasive species coordinator.
All Oregon boaters with craft 10 feet or longer are required to purchase a $5 aquatic invasive species prevention permit. For motorized boats, it comes with the registration.
Several years ago, Diamond Lake's formerly robust trout fishery fell on hard times, partly because of tui chub brought in illegally by bait fishermen.
That led to a rotenone treatment of the entire lake in 2006, and restocking. A year ago the chub showed up again. This time aggressive tiger trout have been introduced to eat the chubs.
The most recent introductions in the Rogue watershed include yellow perch and spotted bass in Lost Creek Reservoir and fathead minnows in Bear Creek, Van Dyke said. Yellow perch can become stunted and overpopulated, leading to more blue-green algae blooms, he said.
Many years ago the Umpqua pikeminnow (formerly known as squawfish) got into the Rogue, as did the northern pikeminnow in the Columbia. Those fish are known to eat salmon and steelhead eggs.
Invasive minnows such as red-sided shiners in the Rogue compete with juvenile salmon and steelhead in tributaries.
In addition to the stenciled signs on the boat ramps, there are messages for no live-bait fishing, and aquatic invasive species signs at boat ramps.
"We're just trying to create awareness that you can't be carrying around live fish without a permit," Van Dyke said.
Josh Sabota, lead park ranger for Josephine County, said the OYCC workers will also pull noxious weeds over the next few weeks in addition to the boat ramp signage, and repainting other markings on the ramps.
The OYCC was formed by the Oregon State Legislature in 1987 to emulate the Civilian Conservation Corps of the 1930s.
Reach reporter Jeff Duewel at 541-474-3720 or firstname.lastname@example.org