Chapter 1: Burning the Midnight Oil in Klamath Falls

A field site at sucker springs on the edge of Upper Klamath Lake. Two Lost River suckers are spawning in the foreground. A USGS passive integrated transponder (PIT) tag reader in the distance.

The activities during our first three weeks in Klamath Falls were very diverse. Our first day, we finished up all our paperwork. Then, we did a tour of the field sites where one of our species of interest, the endangered Lost River sucker (Deltistes luxates), spawns. We even got to see them in the act. Our first day was a window onto the significance of the work that we do, even though we may not be in continual contact with organisms everyday. A contingent of folks from California Fish and Wildlife was a part of our tour group, and we received a short demonstration from some folks from USGS. I was surprised by just how much collaboration there was between organizations and how many government organizations have offices in the relatively small Klamath Falls.

Each sucker to be released was PIT tagged, weighed, measured, and had a fin clip taken in order to possible perform DNA analysis in the future.

We spent the rest of the week working as part of the sucker rearing team. This involved constructing new tanks for juvenile suckers in the morning, and preparing for and releasing some 2-year-old suckers into the lake in the afternoon. We got to handle individuals while we were tagging and measuring them and while transferring them into the soft-release pen, but we couldn’t actually see them when we removed the net to release them into the lake -due to the low visibility on the water. Some tasks are more rewarding than others, and sometime you gain satisfaction from the goal and the idea of the deed rather than its execution. Sidenote, I hadn’t realized how large Upper Klamath Lake truly was until I was on it. It’s huge! It takes 25+ minutes to go from the southernmost to the northernmost point on plane in a powerboat.

Floating soft rearing pen. Klamath Falls Fish and Wildlife Office (KFFWO) is currently testing different methods to improve growth in juvenile suckers. One method is rearing them in net pens on the lake.

The hatchery is being expanded to account for an expanded effort (rearing 30,000 opposed to 10,000 suckers this year).


There are three species of sucker that are endemic to the Klamath Basin. Two are endangered: the shortnose sucker (Chasmistes brevirostris) and Lost River sucker. One is not: the Klamath largescale sucker (Catostomus snyderi). 

In recent years, there has been a decline in the total population of the two endangered species as the older individuals die off and juveniles fail to be recruited into the adult population. The cause of this is not quite known. Adult suckers are extremely hardy and can withstand large changes in pH and temperature. Juvenile and larval suckers are possibly troubled by increased turbidity in the lake (which would affect their ability to hunt for the zooplankton that they eat) caused by effluent from adjacent agricultural fields. There have also been harmful algal blooms that occur in the summer, which juveniles cannot withstand.

To combat this, KFFWO captures larval suckers as they drift towards the lake from spawning sites in the Williamson river. They then raise them for 2-3 years and re-release them into the lake. The hope is that larger fish will be able to survive to adulthood.

Our second week we worked the night shift. Larval suckers have some control over there moment and drift downstream at night, the peak flow is from 3am-5am. This meant that we spent a week working from 2am – 10am. We would attempt to collect larvae using plankton nets from ~2:30 – 4:30. We didn’t catch any our first week, and it’s hypothesized that the weather is was a bit cold for the season. We spent the rest of the time continuing to prepare the grow site for fish. It was a very sleepy week. We’ve got another five weeks of a similar schedule on the docket. I hope I’ll get used to it by the end.

This week we’ve been working on our electrofishing certification to prepare for a later project. It’s pretty jarring to go from the night shift in the field to the desk in a cubicle, but it must be done. To top it off, they caught the first larvae on Monday this week! The first day we didn’t take part. We’ll have something to look forward next week when we roll out of bed at 1am.

Brianne Nguyen

USFWS, Klamath Falls Fish and Wildlife Office

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