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ROSEBURG, Oregon - Oregon Department of Fish and Wildlife biologists are using the fish ladder at the Nonpareil Dam near Roseburg to help them learn more about the relationship between hatchery and wild coho salmon in the Umpqua basin.
ODFW and a team of local supporters converted the fish ladder to serve as a fish trap, and biologists are trapping fish and collecting genetic samples to determine whether hatchery fish can successfully be used to supplement wild populations. The samples also help them understand the effects hatchery fish have on wild fish.
The study is part of the Conservation Hatchery Improvement Program, designed to improve and modernize coastal and Lower Columbia River hatchery programs. A joint effort between ODFW and Oregon State University, its purpose is to develop and evaluate new hatchery programs that help restore wild populations.
This year, as salmon move upriver to spawn, wild and hatchery coho are funneled through the trap to the ladder. While the fish are in the trap, biologists take genetic samples and check for known hatchery fin marks to determine whether the fish came from hatchery or wild stock.
"The genetic samples from these fish will tell us exactly what pair produced which juveniles and whether the hatchery fish were released as fry or smolts," said ODFW Project Crew Leader Dan Jenkins.
After the fish have been checked for sex and size, the returning spawners are released to spawn naturally in the upper Calapooya streams. Comparing genetic samples obtained at the trap with the DNA of future offspring helps fishery managers understand what hatchery strategies produce the most offspring.
"We want to find out what differences, if any, may exist between wild and hatchery coho, if biologists choose to use hatchery fish as a tool to rebuild wild populations," said Jenkins. "Also, in time we hope to learn what effects on production have resulted from introduction of hatchery fish into a wild population. These are important questions that have been asked by many people involved in fisheries restoration."
The project, conducted in support of the Oregon Plan for Salmon and Watersheds, began in 2001 when biologists obtained genetic samples from all adult wild fish that returned to the Calapooya River and monitored their progeny in following years.
Biologists now are developing a clearer picture of which group had the most returning fish and whether the returning fish were released as fry or as smolts.
Information collected through the mid-point of the study suggests spawner returns from fry releases, as predicted, are much lower than the smolt releases. Hatchery-by-hatchery crossed smolts performed better than wild-by-wild smolts, and hatchery brood fish fared better than wild brood fish produced in hatcheries.
"The preliminary results are from just one data collection point for this experiment," said District Fish Biologist Jim Muck. "As fish continue to return, we look forward to determining what correlation exists among the different years."
The project will be completed in 2009, when all the hatchery fish have returned to the system and the long-term results of overall fish production can be compared. It is funded with $505,000 from the Oregon Water Enhancement Board.
For more information about the Oregon Department of Fish and Wildlife, go to http://www.dfw.state.or.us/