Hatchery fish may give false population figures in Wild Salmon

Scientists have found that only about ten percent of the fall-run Chinook salmon spawning in California's Mokelumne River are naturally produced wild salmon. A massive influx of hatchery-raised fish that return to spawn in the wild is masking the fact that too few wild fish are returning to sustain a natural population in the river.

"We expected to find hatchery fish, but the sheer number of hatchery fish returning to spawn in the wild is surprising," said first author Rachel Johnson, a fishery biologist affiliated with the Institute of Marine Sciences at UC Santa Cruz and with the Bay-Delta Office of the US Bureau of Reclamation. "It looked like a healthy population of fish returning to spawn, but the reality is that without the hatchery fish the wild stocks are not sustaining themselves." Read more ...

This blog is written by Martin Little, The Aquaculturists, published and supported by the International Aquafeed Magazine from Perendale Publishers. To get your copy of 'PPLAPP' click here.