Tag Archives: featured

June 2015 Fieldwork Report

We just completed a 15-day marathon of sampling to begin our first real field season. Despite experiencing the setbacks and equipment failures inherent in any first attempts at a complicated protocol, we obtained several good data videos from all three study sites.

Here’s a 7-minute video of our work and some of the fish video:

Each data set consists of a stereo pair of high-definition videos of feeding fish (calibrated for 3-D measurement), a drift net sample representing the prey available to the fish in the water column during the time we were filming, and diet samples from several fish collected immediately after filming. Ideally the stomach samples come from the same fish we observed on video, and we had a high success rate capturing the exact fish we wanted with a well-placed dry fly (except for the tiny Chinook salmon, which we captured with a dip net). We also collect physical data such as water temperature and a spatially explicit map of water velocity, which we measure with the 3-D video system by throwing velocity tracers (neutrally buoyant pieces of Israeli cous cous) into the water upstream of the filming location after we’re done with the fish. We will use these data to test model predictions of the feeding behavior of the fish against many aspects of their real feeding behavior, including the spatial distribution of prey captures, the size structure of their diet, and the rate of prey captures.

First we worked on the Chena, filming very young juvenile Chinook salmon.

Josh and Sierra preparing the calibration frame on the Chena


A tarp protected our solar battery and the viewers receiving and recording the HDMI feed from the cameras.

Sensitive electronics under the tarp


A drift net was generally placed in line to experience a similar density of insects as the fish we filmed, but far enough away that we could place and remove it without disturbing the fish.



Cameras set up on a school of juvenile Chinook salmon downstream

On the Chena we used a 100-micron drift net side-by-side with our standard 250-micron net to capture the tiniest prey consumed by small juvenile salmon.

Coarse and fine mesh drift nets set up upstream of the fish

After the Chena and a two-day break to fix or modify equipment, we backpacked hundreds of pounds of sampling gear far up Panguingue Creek to film its small population of dwarf dolly varden. Half-way through this trip, Professor Grossman came up from Georgia to join us for the remainder of the month’s sampling.

Searching for dolly varden to film with the GoPro-on-a-stick whi Camera set up in the shade filming a dolly varden

We photograph every specimen we stomach pump, so that we can determine which diet samples correspond to which fish on the video.

Dolly varden in the measurement tank

After another two-day break to upgrade our batteries, camera mounts, and other things, we boated to the Clearwater to begin work on Arctic grayling. The beautiful sunny weather we experienced on Panguingue Creek was replaced by a smoky haze as a million acres of Alaska went up in flames in every direction (but none close enough to threaten us directly).

Sierra casting into the mist

The smoke turned the sun a crazy shade of red in the evening.

A crazy blaze orange sun setting through a smoky haze over the C Cameras set up recording grayling in the Clearwater

The purpose of the balloon is to prevent boats from running over our cameras.

A full camera and net setup on the Clearwater Josh carrying the calibration frame A pretty grayling in the measurement and photo ID tank Two goldeneyes on the Clearwater

Each trip ended with a long list of things to make, fix, do, or improve. By the end of our last video recording we were limping back to base camp at midnight after a 14-hour day, covered in no-see-um bites (never previously a problem for me in Alaska, they were as bad as North Slope mosquitos for an hour or so), in a jetboat jump-started from a camera battery which only had juice left because of a different glitch in that system. The thickest midge hatch I’ve ever seen made it impossible to drive the boat without sunglasses, and even then I was constantly wiping my eyes to clear out the ones that slipped past the glasses. We all slept really well that night.

Midges on my windshield (plenty got in my eyes anyway)

As you can see in the video, it wasn’t all that rough. We all had some fun fly fishing during breaks in places that wouldn’t disturb our filming. Josh and Sierra, our field techs, are both fairly new to the sport but catching on fast:

Sierra bringing a nice grayling to the net


Josh's 18-incher

We look forward to returning to the field in July with everything relatively streamlined and polished, ready to collect even better data.

Capturing Chinook salmon fry for foraging experiments

Part of our project involves sending a small number of juvenile Chinook salmon to our laboratory in Georgia, where we can test their feeding behavior in a controlled environment varying a single variable, such as water velocity, at a time. (Needless to say, we are in close contact with Fish & Game throughout this process and maintain the required permits in both states.) It was near the end of the Alaska field season before the lab was ready to receive fish.

Home logjam of most of our Chinook


A driftwood fire helped me and my field assistant (this time, my wife) keep warm while the minnow traps soaked in a logjam where we saw some juvenile Chinook salmon.

Passing the time


It didn’t take long for the traps to gather enough fish.

Extra trapped fish we released


I packaged the fish very carefully in multiple heavy-duty aquarium bags, filled with oxygen, and surrounded by ice packs in insulated seafood shipping containers. Then I sent them on their way via Alaska Airlines, taking the same route to Atlanta that any human passenger would. In less than 24 hours they were acclimating in their new home.


As of this writing, four months later, they are still alive and well in the lab and providing valuable data in ongoing feeding experiments.

Mapping our dolly varden study stream

On August 7, 2014, I spent a long day on Panguingue Creek scouting, mapping, photographing, and taking notes on more than 30 pools to help identify the best representative study reaches for the remainder of our work. I brought along my fly rod and an underwater camera system to sample dolly varden and grayling and note their distribution and relative abundance throughout the creek.

The previous day I had briefly investigated (and ruled out) other possible study sites to the south. I car camped near Panguingue Creek along Stampede Road, where a wolf trotted past as I got ready to sleep, and a nice view of Mount Healy in Denali National Park greeted me in the morning.

Mount Healy in Denali National Park viewed from Stampede Road
Mount Healy in Denali National Park viewed from Stampede Road

The water on Panguingue Creek was high and tea-stained from this summer’s incessant rain, complicating the already difficult wading on its substrate of slippery boulders and cobbles.

Much of the stream flows too fast or too shallow even for the dwarf dollies we’re studying.



Grayling were mixed in with the dollies, and they dominated the larger pools. They were all very small compared to what we see in the larger rivers, but it’s good for our study to test our foraging models across a wide range of fish sizes and species.


I caught enough dwarf dolly varden to get a good feel for their distribution and the sections of the creek where we can best study their behavior and habitat. They are gorgeous fish, reminiscent of eastern Brook Trout, and even the very largest adults (like the 9.25″ male pictured below) retain their juvenile parr marks (dark vertical bars on their side).

A reminder to any local anglers who see this post: This is a very small stream with a small population of dolly varden. It's difficult to access and catch even a few, but if you do, please practice catch and release and handle the fish with care!
A reminder to any local anglers who see this post: This is a very small stream with a small population of dolly varden. It’s difficult to access and catch even a few, but if you do, please practice catch and release and handle the fish with care! They’re too scarce and beautiful to eat when there are ponds full of stocked char all over the interior Alaska road system.


At one point, far from the road, a massive beaver dam blocks the creek… but there were fish both above and below it.

Real height of dam (I'm standing closer)

I returned to the car after more than twelve hours on the stream and an hour-long bushwhack out, with exactly the data we needed to focus the rest of our study productively.