3 million Salmon smolts

I find it real interesting that so many return to other rivers then from where they are  hatched. Maybe it's not imprinting like we have been taught. Maybe they return to healthier waters no mater where they hatch? Just a thought. Hopefully most of the buggers make it!
 Randall


California Department of Fish and Game News Release FOR IMMEDIATE RELEASE - May 10, 2010 Contact: Harry Morse, DFG Communications, (916) 322-8962 DFG to Release Three Million Salmon Smolts Near Mouth of American River Three million young Chinook salmon, or smolts, will be released at the mouth of the American River the week of May 10. They were raised at Nimbus Hatchery on the lower American River by the Department of Fish and Game (DFG). The release site was selected based on new information and studies that show young salmon released near the mouth of their home river are more likely to return to that river two to five years later to spawn.  "Our goal is to increase the spawning returns of fish reared at Nimbus Hatcheryto the lower American River," said Senior Environmental Scientist Joe Johnson of DFG's Central Region."Last year more than half of the salmon returning to the American River originated from the Mokelumne, Feather or Upper Sacramento rivers. This year we're taking clear steps to ensure that more fish return to the waters where they were raised." The adult salmon's journey is tracked through the use of coded wire tags that show when and where they were tagged and released. Starting in 2007, 25 percent of 32 million salmon smolts released in the Sacramento River system were imbedded with these minute tags.  A major goal of river releases is to improve the genetic integrity of each river's salmon populations. DFG biologists are working to decrease straying rates between rivers, where adult salmon return from the ocean and spawn in a different river than the one they were born in.  The Jibboom release site, which is located slightly down stream of the mouth of the American River, was selected after biologists reviewed release and return data from numerous sites. They found that a large number of smolts released from the Jibboom site in previous years were returning to the American River.  To ensure the highest survival rates of the smolts on their down river migration, DFG and the Bureau of Reclamation (BOR) are coordinating release timing, flows and closure of the Cross Channel Gates operated by BOR during the short migration period.

Wow...that's good to know.  Thanks for the post Randall.

I wonder how much they have actually studied the "imprinting" process and at what stage of life it occurs. It may even be a process the embryo undergoes before the egg even hatches. I would think that by the time those fish have grown into smolts, their brains have fully developed in regards to lower level and subconscious function such as breathing, heart beat, metabolic control and so on, as well as even some higher level function such as swimming, predator evasion, feeding skills... It may be that by the time they have grown into smolts, the imprinting process has long been over with thus the fish do not really associate their release spot as their home water.

Here's an interesting article on "homing" and imprinting for pacific salmon - http://jeb.biologists.org/cgi/reprint/199/1/83.pdf