A select group of Rogue River spring chinook salmon are getting some colorful bling as part of a test to see whether they're staying true to their schools or running astray.
Recent batches of excess hatchery spring chinook recycled from Cole Rivers Hatchery back into the Rogue are sporting spaghetti-like floy tags in addition to the traditional punched hole in the gill plate denoting their "retread" status.
These tags will make it easier this fall for research crews counting spawned-out fish to judge whether any of these recycled fish are straying onto wild spawning grounds — a relative no-no under current management plans.
The tags also will give hatchery workers a little insight into how long it takes a recycled fish to re-swim the 46 river miles should they return to Cole Rivers after getting the one-way truck ride to the ramp at Gold Hill.
"My objective is to get as many of these hatchery fish harvested as possible," says Dan VanDyke, the Rogue District fish biologist for the Oregon Department of Fish and Wildlife.
"It's a program I'm certainly excited about, and this is the first year we've been able to recycle these numbers of fish," VanDyke says.
So far, 3,434 spring chinook have been recycled for anglers this season, and the last 100 are scheduled for release next week.
Under current management plans, hatchery workers can a recycle up to 4,000 excess springers each season, but none after July 1 to reduce the likelihood of straying.
The tags contain no numbers and there are no rewards for catching these fish, other than the culinary reward that comes from eating some of the tastiest table fare Oregon has to offer.
But there could be more.
Should the new tagging program show extremely low stray rates, the recycling program could be expanded to give more hatchery springers a second chance at ending their life cycle on barbecues and in smokers instead of concrete holding ponds.
"That's certainly a possibility," VanDyke says. "These are fish for anglers, and we want them to catch the excess."
Stray rates are always sticky subjects when it comes to rivers sporting overlapping wild and hatchery runs. To protect the genetic integrity of wild fish, biologists try to reduce as much as possible the number of hatchery fish that spawn with wild ones.
On the Rogue, the primary wild spring chinook spawning grounds are in the mainstem river upstream of Shady Cove and in lower Big Butte Creek.
Survey crews each fall walk and float these sections to count dead, spawned-out fish and count egg nests, called redds. Hatchery fish are noted by the clipped adipose fins.
Unlike other river systems, the Rogue does not seem to have a problem with hatchery strays, VanDyke says.
Surveys since 2004 show a running average of 12 percent of wild spawning fish to be of hatchery origin, VanDyke says. Last year, however, it was just 4 percent, he says.
The goal under the Rogue's management plan for spring chinook is a 10-year average stray rate of less than 15 percent, "so we're meeting our objective for desired status right now," VanDyke says.
While the traditional punch to the gill plate helps hatchery workers identify recycled fish, the technique doesn't work as well for counting strays because the gill plate where a hole gets punched can often decay and be undetectable.
The two-inch tags jutting out of the chinook's back near the dorsal fin will go a long way toward getting accurate spawning-ground records.
However, not all of the recycled chinook this year have been marked.
On the second week of June, 140 springers were marked with green floy tags, and another 120 were marked with orange tags the following week.
The 100 chinook recycled Tuesday had pink tags, and the final 100 set for release next week will have red tags, says David Pease, the hatchery's interim manager.
The varying tag colors will allow hatchery workers to tell how long it took for any recycled fish return to the hatchery should they do so, Pease says.
Five green-tagged spring chinook were captured in the hatchery trap Monday, Pease says.
Anglers who catch one will know when those fish were recycled, as well.
So far, one angler reported catching an orange-tagged springer at Hayes Falls on Sunday, five days after it was returned to the Rogue, VanDyke says. A green-tagged fish reportedly was caught at the Hatchery Hole earlier this week.
And more stories of springers that once reached hatchery collection ponds but eventually ended up as dinner will dribble in.
"This is one way we can give anglers one more chance at these fish," VanDyke says.
Reach reporter Mark Freeman at 541-776-4470, or email firstname.lastname@example.org. Follow him on Twitter at http://twitter.com/MarkCFreeman