Poor Klamath River Water Conditions, Deadly Parasite, Prompts Fish Hatchery to Delay Salmon Release
For the first time in its 55 year history, the Iron Gate fish hatchery, which raises salmon and steelhead, will not release its salmon smolts into the Klamath River this summer.
Due to poor water conditions and an increase in a parasite called C. Shasta in the river, the hatchery, located in Hornbrook, California, will keep the tiny fish until fall.
Now, the hatchery is dealing with the logistics of moving millions of fish to other facilities because they cannot accommodate all of the growing salmon.
“ We trucked over a million fish three hours from Iron Gate reservoir,” says Mark Clifford, an environmental scientist with California Department of Fish and Wildlife. “We took them to our Trinity hatchery facility and those trucks went through Redding when it was like 115 degrees. And I am happy to say that the fish arrived safely. They are doing great.”
A variety of weather factors have contributed to the growth in levels of C. Shasta, which can be deadly for fish if the concentration is too high.
“Two of the key things are temperature and flow,” says Sascha Hallett, an associate professor at Oregon State University. “Warmer water, especially in the spring, speeds up the parasites' development so it becomes present in the river, in the water column, sooner and therefore able to infect the young salmon sooner.”
The Iron Gate fish hatchery is looking not only to protect their own salmon but also improve the conditions in the river in general.
“The fish would just be an additional host for that pathogen,” says Clifford. “[Releasing them] would amplify the pathogen, which would then impact wild populations”
This danger was made clear in May, when the hatchery released a first batch of salmon smolts. Up to 97% of them were infected with C. Shasta and many died. This level of infection was unprecedented in the area.
“What is unusual here is that disease outbreak is not usually observed in the wild,” explains Hallett. “Because the fish are quickly removed from sight. They either sink to the bottom, like in the Klamath they can sink to the bottom of eddies or deep pools and also they are predated upon either by larger fish or birds. For there to be so many fish that they are not removed from the system really emphasizes the severity of the outbreak this year.”
Because of the seriousness of the parasite and generally poor water quality, the hatchery is waiting for the cooler temperatures and faster water flow that autumn brings to release their salmon. In the fall, when the conditions of the Klamath are deemed healthy, all of the salmon will be brought back to this particular hatchery, so that they will imprint on the chemical signature of the Klamath and return to the river to reproduce.
In the future, hatcheries and other river management organizations have several options to try and ensure that they release salmon that will be healthy enough to make it out to the ocean. The first is a managed flow event, where the river is flushed, usually in the winter. This disturbs the sediment and disrupts the conditions that are needed for C. Shasta to flourish.
The other option, like the one that the Iron Gate Hatchery took this year, is to wait for the optimal time to release their salmon, even if this means waiting until fall.