Wildlife Officials Begin Tagging Spring-Run Chinook Salmon Ahead of Spawning Season

The California Department of Fish and Wildlife (CDFW) has begun tagging Chinook salmon ahead of the fall spawning season.

The CDFW, in partnership with staff from the California Department of Water Resources (DWR), has started tagging spring-run Chinook salmon at the Feather River Fish Hatchery in Oroville, the agency announced in a social media post.

The tagging enables wildlife officials to identify early-arriving spring-run Chinook salmon from those that arrive later in the fall during spawning operations.

The Central Valley spring-run Chinook salmon was listed as a threatened species under both the state and federal endangered species acts in 1999.

Born in freshwater, Chinook salmon are anadromous, which means that they spend most of their life at sea, returning to freshwater to spawn.

The CDFW typically uses Hallprint, a spaghetti-style fish tag, to visually identify spring-run Chinook salmon. The fish are outfitted with two external Hallprint tags on either side of the dorsal fin and are then released back into the river.

Unlike the Passive Integrated Transponder tags that are injected into Chinook salmon smolts (young salmon) to monitor their movements, the Hallprint tags provide better visualization, according to wildlife officials.

The Feather River Fish Hatchery has been working on increasing the population of Chinook salmon to help sustain California’s commercial and recreational salmon fisheries.

The hatchery usually spawns spring-run fish in September and October, selecting only among the returning, externally tagged fish to preserve the integrity of the fish species and not mix them with the fall-run Chinook salmon.

In 2022, the hatchery raised and released 8 million fall-run Chinook salmon smolts, according to the CDFW. The hatchery is owned by the DWR and is operated by the CDFW.

Thiamine Injections to Treat Deficiency

In addition to tagging the fish, officials also injected the Chinook salmon with thiamine, CDFW said in its Facebook post.

The injection helps fight thiamine deficiency before the fish are returned to the river, where they will live through summer until spawning begins in September, officials said.

Thiamine deficiency, or the lack of Vitamin B1, in California’s Central Valley Chinook salmon was first detected in 2020. The deficiency can lead to death in both juvenile and adult fish.

The CDFW has linked thiamine deficiency to booming populations of anchovies in the ocean and adult salmon feeding almost exclusively on anchovies compared to a more diverse diet.

The agency’s thiamine supplementation protocol includes soaking Chinook salmon eggs in a thiamine solution during fertilization, the agency explained in its Facebook post.

After years of closure, California has begun opening salmon fishing across several parts of the state.

Earlier this month, the CDFW announced salmon fishing would return to the Klamath River Basin and Sacramento River for the upcoming summer and fall seasons.

In March, recreational ocean salmon fishing was opened in the waters south of Pigeon Point to the U.S.-Mexico border for the period from April to August.