Water Parasite Sampling in the Lower Trinity Hoopa Valley Reservation

Project Objective: Determine density of relevant salmonid parasites C. shasta and I. multifiliis in river water samples in the Trinity River and in the vicinity of its confluence with the Klamath River.

Project Description: Ceratonova shasta and Ichthyophthirius multifiliis (Ich) are parasitic diseases found in the Klamath Basin that affect salmon and steelhead. C. shasta can have an enormous negative impact on juvenile salmonid survival. Ich can affect both juvenile and adult salmonids and both parasites have a larger effect when environmental conditions are not favorable ie. warm temperatures and low dissolved oxygen. For over a decade there has been consistent monitoring for C. shasta in the mid and upper reaches of the mainstem Klamath but there is only one monitoring site downstream of the confluence with the Trinity River. Sampling for Ich generally only occurs in the fall in the lower reach of the Klamath but has been detected in the spring of 2021. C. shasta was not detected in the Trinity the last time an investigation was conducted about 10 years ago however, given the low water conditions, lack of geomorphic flows, and observed changes in algae in both the Trinity and lower Klamath, it would be prudent to ensure that is still the case. There were fish with clinical signs of C. shasta caught in the lower Trinity in recent years, though the cause of the abdominal swelling was not confirmed.



The Hoopa Valley tribe will collaborate with Oregon State University to quantify C. Shasta spore concentration and Ich trophonts at two locations in the Klamath basin which complement the existing sampling. The sampling will be conducted weekly in the same time as other Klamath sampling and can be used to inform both the existing FASTA team and TRRP staff about conditions in the lower Trinity and Klamath Rivers. The sampling locations are the Klamath mainstem at Saints Rest bar, and the mainstem Trinity in Hoopa and upstream of the confluence with the South Fork Trinity River.

Project Benefit: This information not only complements existing sampling efforts but also serves to facilitate timely interventions and mitigating health risks to salmonid populations. Furthermore, the projects proximity to the confluence offers early warning capabilities for the upper Trinity, enabling proactive measures to prevent adverse outcomes such as fish kills. This flow action has been instrumental in preventing a repeat of the fish kill of 2002.