Hope this helps…the California Department of Fish and Game just completed a release of 16.5 million Sacramento River fall-run Chinook salmon smolts on June 15.
The majority of the fish were placed into acclimation pens in San Pablo Bay prior to release, while others were released in rivers that flow to the bay. Smolts that survive to adulthood will return in two to four years to spawn in Central Valley rivers, boosting the recovery of the species in California waters.
“We hope this year’s above-average water flow and the use of a variety of release sites will improve the overall survival of the smolts and increase the return of adult salmon to their home rivers,” said Neil Manji, DFG Fisheries Branch Chief.
On June 8, the last major release of 650,000 Sacramento Fall-Run Chinook smolts took place near Mare Island Straits adjacent to San Pablo Bay. They were trucked from Nimbus Hatchery in Rancho Cordova to the site, confined in net pens to acclimate and towed out into the bay and released on the outgoing tide. The acclimation pens are operated by the non-profit Fishery Foundation of California (FFC).
Since the collapse of the Sacramento Fall-Run Chinook salmon stocks in 2007, DFG has stepped up acclimation efforts and selected new release sites to help improve survival rates. This year, new sites for release included the mouth of the American River (to boost returns to the American River) and Eddos Harbor on the San Joaquin River near the Antioch Bridge (to boost returns to Mokelumne and Merced rivers).
The releases went well, said Biologist Kari Burr, FFC Acclimation Project Manager. Once adults return and information is collected, biologists will be able to fine-tune release locations for the coming years.
At release sites in the San Pablo Bay and Eddos Harbor, acclimation pens provided safe haven for the 3- to 5-inch-long salmon when they were released from pitch-dark transport tanks into bay and river waters. The pens allow the smolts to adjust to their new surroundings inside the safety of the net pens.
The release sites were selected in order to minimize in-river losses due to predation, pollution and other causes, and to help minimize the number of salmon that return to a different river than the one where they were raised.
The salmon smolts were raised at and trucked in from four DFG-operated Central Valley hatcheries. For additional information, please see the related May 10, 2010 news release, DFG to Release Three Million Salmon Smolts Near Mouth of American River, at dfg.ca.gov/news.