The Adventures of Shocking and Bull Trout

Mid-June marked the beginning of field camping for our crew in Klamath Falls, enabling us to complete surveys at more distant sites. After a week in northern California continuing our assessment of endangered Modoc sucker populations (see Good Night, and Good Suckers or A sucker kind of night), we returned from the Chicago workshop to focus on a new project aimed at improving habitat conditions for threatened bull trout.  The species generally prefers the calm water of stream pools, but years of timber removal have caused the amount of large, pool-forming woody debris to decline, potentially aiding more flexible non-native brown trout in competition for resources. As such, we have been collecting baseline data for an upcoming effort to add new logs to sections of the streams.

Bull trout, medium-large for what we catch (notice the adipose fin has been clipped)

Electrofishing among woody debris, with netter ready to scoop up stunned fish

We accomplish this through mark-recapture and remote detection of PIT tags (similar to methods for adult suckers), but instead of nets, we use backpack-mounted electrofishing units. Current traveling through the water between the anode (ring at the end of a wand) and the cathode (wire that trails behind) briefly stuns any fish within a few feet, just enough time to allow retrieval by dip net.

Processing set-up

Scanning for tags with mobile antenna

Processing is performed as a three-bucket system, with each fish receiving a small dose of anesthetic prior to measurement, tag injection and clipping of their adipose fin (a means of quantifying tag loss, hopefully without significantly impacting swimming ability). On later visits, a stream section can be shocked again or a mobile antenna device can be used to scan for the tags without capture (an easier and less invasive technique, but with a lower detection rate based on tests where we temporarily block-netted the top and bottom of a section).

Electrofishing backpack unit, with power button conveniently located too far back for the wearer to reach

I’m pleased to report no serious incidents despite playing with electricity in not-quite-waterproof waders, thanks to a safety-conscious crew. The shocking units also contain a number of fail-safes, including sensors that will cut off power in the event of water contact or even a low tilt, adding some peace of mind. Actually, the biggest danger has been running into branches and slipping on rocks in the stream channels, which certainly boost one’s appreciation for unobstructed walking. Still, it keeps us reasonably cool and out of the sun, so I can’t complain too much considering the unrelenting heat of some of the locations other interns have to deal with. In fact, at such high elevation, we actually woke up to snow covering our campsite one morning in late June!

In between bull trout surveys, we’ve also completed some wetland vegetation mapping in the delta of the major tributary to Upper Klamath Lake, which was re-flooded within the last few years after having been drained and used as farmland for decades. We hope to quantify the amount of edge habitat suitable for juvenile suckers, and identify how that availability will change at different lake levels. This has involved my introduction to Trimble GPS units, which although somewhat finicky and counterintuitive, produce amazing results coming after years of accepting a 10-meter error as a given. It also gave me a chance to check out the beginnings of the annual “algal” bloom (actually AFA cyanobacteria), which grows unchecked due to its ability to fix nitrogen and the volcanic region’s abundant supply of phosphorus. When it crashes, its decomposition reduces dissolved oxygen in the lake, potentially contributing to juvenile mortality in shortnose and Lost River suckers. On top of that, the blooms are often highly toxic. Needless to say, Klamath Lake is not known for its swimming.

Delta vegetation with Mt. McLoughlin and eagle in background (foreground, poor water quality)

Aerial view showing section of re-flooded delta area

Beyond these, I’ve made use of our limited time out of the field chugging through more sucker specimen photos, compiling spatial data with ArcGIS (it’s surprising how much you forget, being away from it for a year), and preparing for upcoming grass and sucker surveys. Outside of work, I’ve been hiking most weekends, including the snow-capped Mt. McLoughlin just west of the lake and the spectacular, obsidian-laden Glass Mountain on the edge of the Medicine Lake Volcano in northern CA. Keeping busy.

I enjoyed meeting everyone at the workshop last month – hope everybody’s field seasons continue to go well!

– Tommy Esson (USFWS, Klamath Falls, OR)

Good Night, and Good Suckers

Our experience at the Klamath Falls FWS office is coming up on the one month mark following the transition from adult sucker sampling with GS, and a surprising amount has been packed into a relatively short time. As the last post (A Sucker for Suckers, cont.) mentioned, a lot of our effort has gone into sampling at a pond where about 200 juvenile shortnose and Lost River suckers were released a year ago after getting trapped in the canals that divert water from Upper Klamath Lake. Recapture rates with the fyke (hoop) nets set overnight have been slow so far, but we’re still testing different net placement strategies and detection techniques, including cast nets and a portable scanner. We have also dealt with an experiment in the lake to examine the effects of gravel substrate size on sucker egg development, and meanwhile at the office I have just begun working on a project to take detailed photos of juvenile sucker specimens that will later be analyzed along with x-rays to identify distinguishing body shape and skeletal characteristics for more accurate species differentiation.

At the Lower Klamath NWR sucker pond. We went beyond the sign.

Cast netting at the sucker pond. Didn't catch anything, but it looks nice.


Our main focus now is on the Modoc sucker, a smaller species that, while restricted to a fairly limited range of streams in southern Oregon and northern California, appears to have improved considerably since its listing with the ESA. Visual surveys are performed by spotlight late at night when the fish tend to be more out in the open and stationary. We found them in substantial numbers throughout the stream reaches that we have surveyed so far, and if this trend continues, a recommendation may be put forth to have the species downlisted to threatened.

In addition to the sucker work, we have performed egg-mass surveys for the Oregon spotted frog (a candidate species for listing that has been severely impacted by hydrologic changes and bullfrog invasions), and nest surveys for bald eagle chicks (as part of a five-year monitoring program required after its 2007 delisting).

Oregon spotted frog

Bald eagle nest (lower right) and parents (side by side at top).













With bull trout electrofishing, vernal pool plant surveys, river delta habitat mapping and bat detection equipment testing (among others) still ahead, this internship is turning out to be an incredible opportunity for sampling a wide array of projects, species, study areas and field methods – not to mention an exercise in organization and time-management.

Oh, and I have to include a compliment to the location:

Tommy Esson

USFWS, Klamath Falls, OR

The Mighty Suckers

First, an introduction:

Lost River sucker - larger, more docile, and oh so lovely

Shortnose sucker - small, squirmy, and kind of cute (in comparison)

Since the last posting on this project (‘A Sucker for Suckers’), we’ve been inundated with… suckers! Katie’s catch of 240 at the weir on the 20th was followed by numbers in the 600s early the following week, providing ample practice handling, transporting and processing the strong, slippery fish. Still, a swift face slap every now and then keeps us on our toes and reminds us that we’re dealing with several feet of disgruntled muscle.

Considering their apparent overall health and relatively large numbers, it’s easy to forget at times that these two species are endangered. The key issue is recruitment of new adults, which basically hasn’t occurred to any significant degree since the early 90s. This means that despite reasonably low death rates (owing to over 40-year lifespans), the current populations are continually aging and declining by about 10 percent each year. The research conducted at GS is therefore divided into two broad goals: investigating potential causes of juvenile die-offs in pursuit of management solutions, and monitoring the status of the adult populations.

Processing set-up with LRS on measuring board (tag scanner below)

Injecting a SNS with a PIT tag just anterior to its left pelvic fin

solar panels power the weir trap antennas in the "city of sunshine"

Weir across Williamson River - downstream trap on right, upstream trap far left

Downloading tag reads at weir trap

One of the aspects of the adult monitoring program that’s impressed me most is the extent to which advances in technology and other innovations have been embraced over the course of the study. We record data on specifically-programmed computer devices to improve processing efficiency, maintain consistency, and virtually eliminate separate data entry. A variety of antenna and power systems in different arrangements are employed to gain the best coverage and signal for picking up the PIT tags depending on conditions at the site. The layout of the weir structure can be adjusted as the spawning season progresses to allow easier passage for fish returning downstream without compromising tag detections. Some of the remote stations have even been set up to send information on battery levels and data volume directly from the field to the office so that the limited personnel can be distributed to areas that are most in need of attention. With all of this, it becomes evident very quickly that a lot more time and effort has gone into maximizing data collection and minimizing disturbance to the fish than most of the general public is probably aware.

This was actually our last week at GS, which may have been for the best since my dry suit finally kicked the bucket on Friday! It’s been a great time, though, and it will be interesting now that we’re transitioning over to FWS to compare the inner-workings of two federal agencies that are tackling some of the same projects from different angles. Next stop: Modoc suckers!

Tommy Esson

Klamath Falls, OR

A Fish Called Sucker

I’ve been working over the past few weeks on a USGS project monitoring the survival and spawning movements of shortnose and Lost River suckers in the upper Klamath Basin of southern Oregon. Named for their distinctive bottom foraging mouths, the two endemic fishes are endangered due to a mixture of factors mainly affecting water quality (an issue that seems surprising judging by our proximity to super-clean Crater Lake just to the north). In an effort to track population behavior throughout the season and from year to year, hundreds of fish have been injected with PIT tags (centimeter-long radio-frequency microchips) that identify each individual by number when scanned or picked up by remote antenna.

Along with another intern, my job has been to assist in the capture/recapture and tagging of suckers in Upper Klamath Lake and its tributaries, as well as the maintenance of detection stations. Sampling is performed by boat using trammel nets, and was described to me fairly accurately as “mist netting underwater” (although thankfully fish have fewer pointy bits to get tangled up by than birds). After carefully cutting the fish out, they’re placed in a tub on board and then transferred to a crew on shore for processing and release.

This all takes place by headlamp at night (when net success is highest), under often stormy conditions, and on a virtually undeveloped and untraveled lake, making for quite the exhilarating and surreal environment. It’s beautiful on calm nights, though, with spectacular sunsets over the foothills of the Cascades.

While I’m still in the early stages of the internship, the experience has been very enjoyable and productive so far, and it is helping to clarify for me how working under a federal agency compares to university research. For one thing, it carries with it a greater sense of responsibility since we’re operating on public dollars, and since conservation efforts on the lake have been at the center of much controversy over water rights, involving a diverse group of stakeholders.

I’m looking forward to the variety of projects and learning opportunities ahead, and assuming that my waders and dry suit hold up, it should be a memorable summer!

Tommy Esson

Chicago Botanic Garden-USFWS & USGS

Klamath Falls, OR