SANTA CRUZ, CA--A recent study indicates that wild salmon may account for just 10 percent of California's fall-run chinook salmon population, while the vast majority of the fish come from hatcheries. The findings are especially troubling in light of the disastrous decline in the population this year, which will probably force the closure of the 2008 season for commercial and recreational salmon fishing.
The role of hatcheries in the management of salmon populations has been a contentious issue for many years. The new findings appear to support the idea that including artificially propagated fish in population estimates can mask declines in natural populations caused by a lack of suitable habitat.
"Our finding that 90 percent of the fish are from hatcheries surprised a lot of people," said Rachel Barnett-Johnson, a fisheries biologist with the Institute of Marine Sciences at the University of California, Santa Cruz.
Barnett-Johnson and her coworkers published their results in the December 2007 issue of the Canadian Journal of Fisheries and Aquatic Sciences. The main focus of the paper is the development of a new technique for distinguishing between wild and hatchery-raised salmon. The researchers validated the technique and used it to estimate the percentage of wild fish among the fall-run chinook salmon caught by commercial fishing boats along the central California coast in 2002.
"It's a one-time estimate for that year, and these things do change over time. But it's the most recent and perhaps best estimate we have," said Churchill Grimes, director of the National Marine Fisheries Service Santa Cruz Laboratory and a coauthor of the paper.
In 2002, the fall run of chinook salmon in the Sacramento River was estimated at 775,000 adults returning to spawn, according to the Pacific Fisheries Management Council. Fewer than 60,000 are expected this year, even with no ocean fishing allowed. If the percentage of wild f
|Contact: Tim Stephens|
University of California - Santa Cruz