Merced River Hatchery (MRH) is located just below Crocker‐Huffman Dam (the terminus of anadromy), north of Fresno. The original fish facility, completed in 1970 by the Merced Irrigation District (MID), was a Chinook salmon spawning channel designed to enhance salmon runs. To increase production, the facility was converted into a spawning and rearing hatchery during the 1980s and 1990s. Operational funding is provided by the CDFG and the Department of Water Resources; CDFG operates and maintains the hatchery. Fall Chinook salmon are the only species reared at Merced Hatchery.
The fall Chinook salmon program at MRH is considered an experimental program to test juvenile to adult survival rates for various release sites in the basin. The original purpose of the program was to mitigate for lost habitat from the construction of the Crocker‐Huffman, Merced Falls, and Exchequer dams. This was to be achieved by producing 960,000 fall Chinook smolts and 330,000 yearlings. The yearling program was discontinued due to high fish losses from proliferative kidney disease (PKD), caused by Tetracapsuloides bryosalmonae, an endemic myxozoan parasite in the Merced River.
Current production goals for the integrated fall Chinook program are to take two million fall Chinook eggs and release one million smolts at 60 fpp (80 mm fork length) between late April and mid‐May. Most releases of Merced River fall Chinook salmon are for experimental purposes. These fish have been marked (adipose fin‐clipped, panjet marked) and coded wire tagged, and the remaining fish are currently marked at a 25 percent constant fractional marking rate with an adipose fin‐clip and coded wire tag. Fall Chinook are released at the hatchery, at lower Merced River locations, and at various locations in the San Joaquin River and further downstream.
Text excerpt from The California Hatchery Review Statewide Report, prepared by the California Hatchery Scientific Review Group, April 2012.