Ecological Fish Farmers

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Ecologists or fish farmers? Yup! From left to right, Cam MacKenzie, Heidi Golden, Linda Deegan, and Mark Urban are now officially ecological fish farmers.

 

You never know where your research questions might lead but species adaptability to climate change brought us in a brave new direction.  As first-time “fish farmers,” we faced challenges knowing when to begin artificially spawning our three Arctic grayling populations (Kup, Oks-Zev, and Oks3) in order to populate our common garden experiment with hand-raised larval fish. If we started too early, the eggs might be immature. On the other hand, waiting too long might cause the eggs to degrade and become non-viable. When our populations showed signs of spawning readiness, such as fish pairing up within the stream, breeding tubercles, and expression of eggs and milt, we pulled out all the stops to catch fish, using combinations of weir traps, fyke nets and angling. We held the fish we caught in large mesh pens within the rivers so we could check their spawning condition daily. However, although we were able to express eggs and milt early on, we mistook mature eggs for immature eggs due to a unique feature of Salmonid oocytes, lipid droplets, which mimicked early stages of vitelligenesis (the accumulation of yolk within an immature egg). After some deliberation and consultation with more experienced colleagues, we proceeded with fertilizing our Arctic grayling eggs. We hit it right-on with one population, the Kup, almost caught it right with another population, Oks3, and flat-out missed it with our third population, Oks-Zev. In my opinion, the condition of our grayling eggs reflected differences in the timing of spawning for these populations, such that Oksrukuyik headwaters likely spawned first, followed by the lower Oksrukuyik, and then the Kuparuk. Discovering what drives variation in spawning timing for grayling populaitons is certainly on my “To Do” list and I already have some testable ideas in mind. As with every field season, we learn something new about this amazing species, the Arctic grayling, and the Arctic tundra stream ecosystem.

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As soon as the icy waters of the Oksrukuyik become wadable, we enter with rebar and fyke nets to set traps for catching spawning-ready Arctic grayling.

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A beautifully set weir-trap on the lower Oksrukuyik Creek awaits upstream spawning migrants.

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These lucky participants await their chance to donate their eggs and sperm to the scientific cause of assessing local adaptation to climate change in our common garden experiment.  Thanks guys and gals!

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Although these eggs appear to be immature vitelligenesis 1 stage, they are actually fully yolked, mature oocytes with oil droplets (orange spots) within each egg.

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We not only extracted fabulous looking eggs from this female, but our PIT tag popped out, as well!  I’ve often suspected that intraperitoneal tagging could lead to tag loss during spawning. Could be something to that.

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After adding milt from the male, these fertilized eggs must be rinsed, water hardened, and then disinfected before we can safely transport them to Toolik Field Station.

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Linda Deegan and Kate Michmerhuizen painstakingly count fertilized Arctic grayling eggs into treatments for a in situ transplant experiment, placing eggs from each of our populations in all three rivers to see who does best and where.

 

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The 2 am Arctic sun casts its rays on Johanna Ruff, Cam MacKenzie, and Kate Michmerhuizen as we take advantage of the “midnight sun” in order spawn all three Arctic grayling populations as close together as possible.  And although not shown here, Greg Hill caught many of the fish in our holding pens by tirelessly angling these reaches.  Now that’s a dedicated team!

 

 

Fishing with Edna

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Back in the “olden days,” if you wanted to assess fish communities, you might set gill nets, fyke nets and traps and hope to capture all the species present in the environment. Personally, I am no fan of gill nets because they tend to kill or maim everything they catch. And, although I love the thrill of opening a well-set fyke net because you never know what might be inside, there’s a good chance you might miss rare or newly invasive species because their detection probability is so low. This year, as part of the Arctic Long Term Ecological Research (LTER) program, we are exploring the power of genetics to detect fish species by sampling the aquatic environment for fish DNA, a.k.a. environmental DNA (eDNA) or as Frances Iannucci and I like to call it, “Edna.”

Environmental DNA is a relatively new sampling technique that uses DNA from organisms, such as skin cells, urine, excrement and other sources, to determine species presence. This technique is incredibly sensitive because it only take a copy or two of mitochondrial DNA in a filtered water sample to detect a species. We are working in conjunction with the US Fish and Wildlife service to develop genetic primers for North Slope fish species in order to detect and monitor changes in fish community structure over time, simple by collecting filtered water samples from our lakes and streams. We also hope to use this technique to assess changes in species abundance using quantitative PCR techniques. With this goal in mind, Frances and I sampled Green Cabin Lake and the Kuparuk River prior to the Arctic grayling spawning migration. We predict the samples will show high concentration of Arctic grayling in the overwintering location, GCL, and no to low concentration of Arctic grayling in the spawning stream, the Kuparuk River prior to spawning. We predict that sampling later in the season, after the spawning migration, will show the opposite trend.  I’m thrilled to be part of this eDNA biodiversity assessment revolution and can’t wait to do more fishing with Edna.

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Due to the sensitivity of eDNA sampling, we needed a clean location, free of fish DNA, in which to prepare our sampling equipment. After a good washing with bleach, Toolik Field Station’s old stable isotope lab provides the perfect location in which to prep our sampling gear.

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Before fishing for fish DNA on the Kuparuk River, we first filter a control sample of deionized water to ensure good quality control for our samples.

 

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Ice covers most of Green Cabin Lake, but open water from the moat surrounding the lake provides enough water to test for fish presence and Arctic grayling abundance.

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A tiny phalarope paddles past, searching for food in a lake caught between winter and spring.

A Trick to Predicting Migration

We always find difficulty predicting the Arctic spring thaw due to the variability of this environment, but knowing when the Arctic grayling will begin their spawning migrations presents an even greater challenge.  In order to raise baby fish in our common garden experiment, we must first capture adults on their way to spawning locations within the newly flowing streams.  Ripe with eggs and milt (fish sperm), these adults provide gametes for us to artificially fertilize and raise from eggs to larvae to fry in our local adaptation experiment.  Between preparing our common garden aquariums and setting up adult fish monitoring antennas, we also check the river temperatures daily using iButton temperature loggers.  I set these tiny loggers to record river temperature at 10 minute intervals to help us gauge when the rivers approach spawning temperatures of 4 to 6 degrees C.  Right now, our rivers are still running cold, hovering close to zero, but it won’t be long before the 24 hours of radiant sunshine warm these streams and the grayling leave their overwintering locations en route to spawning grounds.  We will only have a small window of opportunity to capture these fish because when the time is right, they move fast.  But with a little help from our iButtons, perhaps we can make an educated guess at migration timing and nab them!

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Ice cold river water flows bank-full in Oksrukuyik Creek.

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Trusty iButton ready for deployment.

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We pop the iButton in a bottle, strap it to rebar, tether it to the shore and chuck it in the river.

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A young bull moose indignantly ignores our roaring helicopter rotors. Odd behavior for a moose, so we skipped this site for today.

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Thanks to a well placed iButton, we knew exactly when the Green Cabin Lake outlet began flowing due to a jump from zero to 0.5 degrees at 1:29 am on May 23rd. Science!

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A view of Toolik Field Station shows moating around Toolik. If you look closely, you might make out my little yellow tent on the lake shore.

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A small group of caribou grazes the tundra along our iButton pick-up route near Sagavanirktok River.

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And there’s that crazy moose again! We decided it must be Cam’s spirit animal. ; )

An Uncommon Garden

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Overflow on the Kuparuk River portends the onset of spring and its eminent “ice-out.”

The ability to either move or adapt will largely determine which species will persist under climate change change conditions.  The Arctic provides the perfect setting in which to test predictions regarding local adaptation of populations to warmer climates because the Arctic is warming much faster than anywhere else on earth.  Through my dissertation research, we discovered that the fish we study, the Arctic grayling, consists of many genetically distinct populations, but we now want to know if these populations have evolved local adaptations to their respective habitats. Populations that are locally adapted to warmer watersheds, such as the Oksrukuyik Creek, might fare better under future climate change scenarios.  This season, we are gearing up to test our Arctic grayling populations for local adaptation by rearing individuals from three populations from eggs to fry in an experiment call a “common garden.”  The common garden refers to raising individuals from different habitats under constant conditions in order to eliminate trait differences that might be due to environmental differences among habitats, such as food availability or temperature dependent growth rates, for example.  By raising them under common conditions, we can be certain that any trait differences we find among populations are due to genetic differences that have evolve over time, a.k.a. local adaptation.

Our common garden experiment consists of three water baths set at three different temperatures, 8, 12 and 16 degrees C.  We chose these three temperatures because they reflect summer averages of the rivers in which our fish populations live, the Kuparuk River = 8 degrees C and the Oksrukuyik Creek = 12 degrees C, and future climate change conditions, 16 degrees C.  It sounds simple, but maintaining constant water temperature in the Arctic is trickier than you might think.  Last year’s trials showed larger temperature swings than we liked and our temperature regulating system failed when outside temperatures dropped below freezing.  This year, we have added in-line spa heaters to our water baths and increased insulation by wrapping pipes and adding insulated lids to compensate for low outside temperature.  We also added a temperature controller that turns on either the water chiller or heater when the temperatures drift higher or lower than our ideal settings.  Fingers crossed that these adjustments will do the trick to maintain temperatures for raising baby Arctic grayling in this rather uncommon garden.

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Cameron MacKenzie and I head out from Fairbanks to Toolik Field Station on Alaska’s North Slope, Oreos and Gatorade provide sustenance for a long drive up the Haul Road. 

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My marigold makes it to the Yukon River!

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Looks like winter, but feels like spring at Toolik Field Station.  Although snow is still on the ground, sunny days will quickly turn frozen rivers to raging torrents.  No time to waste in preparing for ice-out and Arctic grayling spawning migrations.

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I found the missing piece!  We spent hours driving around Fairbanks looking for parts for our common garden experimental tanks.  This piece was particularly difficult to locate.  Yet, I found a small catch of them here in the tool shed at Toolik.

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Loaded with supplies still to be unpacked, our common garden facility (a.k.a. The Fish Spa) begins to take shape.

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After multitudes of email exchanges and phone calls with Jeb Timm, Toolik’s science support manager, we decided upon this design to maintain temperatures in our experimental tanks: a 1.5 hp water chiller and an in-line spa heater both controlled externally by a thermistor regulated temperature controller.  It’s a little leaky for now, but seems to do the trick.

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The LIMS site (Lower I-Minus Spring), a newly discovered spring, provided open water all winter and formed this menthol blue ice field, known as an Aufeis.

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Bear at the KUS pool! This rascal discovered our fish in this spring-fed area of the Kuparuk River, which provides overwintering habitat for Arctic grayling.

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Now we know who’s been eating our fish!  Although fish might survive the winter in the KUS pool, predators, like bears and gulls might cause increased mortality for fish because fish in these cold shallow springs become easy pickins.  I opportunistically collected this fish’s otoliths (ear bones), which hold important age and life-history information, and a fin tissue sample, for genetic analysis.  We left the rest of our bear’s lunch behind to be polished off by the bear and birds.

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We spotted a moose at our KLAS (Kuparuk Lower Aufeis Spring) site.  She was so large that we suspect she might have been pregnant with a calf or two.

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Yet another bear!  We spotted this bear near our old Kup7 antenna locations.  What a great day for wildlife sightings!

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Even though it’s still freezing at night and there’s always a chance the wind will shift to northerly, I pitched my tent by the lake.  I never want to forget where I am and how lucky I am to research and explore this amazing land.

Scenes from I-Minus

Intent on capturing the spring spawning run and collecting and fertilizing Arctic grayling eggs for our local adaptation experiment, we set out on foot to the remote I-Minus lake camp. Kate Michmerhuizen and I were at this site for almost two weeks, intent on capturing and tagging as many Arctic grayling as possible during the spring spawning run. We also collected fin tissue samples for isotopic and DNA analysis and tried to collect gut content samples from predatory fish, as well. We stopped collecting guts, however, when we realized the fish were “gulpin’ sculpin” that were trapped with them in our fyke net! While Kate and I monitored the I-Minus outlet stream, Cam MacKenzie and Tom Glass were checking on our other two rivers, Oksrukuyik Creek and the Kuparuk River, also looking for signs of spawning Arctic grayling. During our stay at the I-Minus camp, we saw the beginnings of what we term “spawning readiness,” with bumpy protuberances (tubercles) on some fish and even a few with milt and eggs. We also experienced “all the weather.” You name it, we had it! We captured five fish species, almost all the species on the North Slope, including Arctic grayling, lake trout, burbot, white fish and slimy sculpin. See below for images of our work at I-Minus.

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Group selfie of the Spring 2016 Fishscape crew. Cam and Tom will fish lower Oksrukuyik Creek, while Kate and I tackle the I-Minus system.

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Freeing the IM1 antenna from river ice prior to ice-out on the I-Minus outlet stream.

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Down-time in the relative warmth of our tent.

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Layers of lake anchor ice successively rising from the bottom to the surface form floating ice sculptures on Lake I-Minus.

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Chilly weather freezes our wet nets almost immediately.

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Schlepping a seine net across the outlet stream.

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Smooth dangling ice baubles juxtaposed against wind derived spikes of hoar frost reflect in side pools along the I-Minus outlet stream.

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Kate readies the tagging station used to weigh, measure and tag the fish caught in our weir trap.

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Rebar on our weir trap needs adjustment as permafrost thaw depth gradually increases with warming temperatures.

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We named our last sik sik neighbor “Boots” after she nibbled Cam’s hikers.  This rascal’s named “Crocks.”

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Porcupine foot prints near our campsite.

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Harnessing solar power allows periodic use and charging of some electronics while in the field.

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Goblet likens amid moss fronds invoke fairyland visions.

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Tea break while waiting for fish to find our gill net, which is set perfectly in the background.

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I-Minus camp before snow.

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I-Minus camp after snow.

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Arctic grayling pink striped pelvic fins. It’s impossible not to adore this fish.

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Hiking out from I-Minus camp, back to home-cooked meals and showers at Toolik Field Station!!

Changing States

The Arctic took a mighty turn today, changing states from solid to liquid faster than conceivably possible.  Often during spring thaw, lakes thick with ice show signs of moating, where ice around lake margins thaws more rapidly then elsewhere, literally leaving a moat around the perimeter of a frozen interior.  This year, snow degraded so quickly due to two days of consecutive warm weather that surface water filled the still frozen rivers spilling massive quantities of tannic water, turned brown from decomposing tundra plants, out over the Toolik Lake ice.  Standing waves in the Toolik inlet indicate mass quantity and raw power of the Arctic spring thaw.  A trip to our study rivers revealed a coursing Oksrukuyik Creek and a Kuparuk River soon to follow suit.  With rivers flowing and joined now by field assistants, Tom Glass and Kate Michmerhuizen, we must quickly shift gears to our remote field locations, where we’ll capture and tag migrating fish.  No WiFi at I-Minus Lake, so no updates for a while.  Cheers!

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Toolik inlet rushes over anchor ice and over the still frozen surface of Toolik Lake.

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Safely out of the inlet’s grasp, our T-In antenna remains high and dry for now.

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Structures greater then the Toolik inlet bridge have caved to spring floods, so after a quick thrill dangling my feet over the edge, I’m outta here!

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Flood waters inundate Toolik Lake’s thickly frozen surface ice as winter gives way to spring in the Arctic.

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Oksrukuyik Creek shows similar but less dramatic flow to the Toolik Inlet, with water rushing over anchor ice.

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Cotton grass displays early sign of flowering. These baby yellow-green flowers will give way to fluffy white tufts later in summer.

Fish in the TOAS Pool

With snow conditions predicted to degrade rapidly after today, we set out for the TOAS pool to retrieve our vertical fish antenna and any data it might have collected while deployed.  Water seeping from our hole left a slushy mess at our site, but only a thin ice layer covered the spot where our antenna lay.  A few chops with a wide blade ice scraper and our antenna slipped easily up from the depths.  Leaving only our iButton temperature logger behind to gather more data, we eagerly returned to Toolik Field Station with fingers crossed in hopes of fish detection.  Downloading the data to our “DuraBook” (total misnomer btw) we found six unique tag detections from Arctic grayling that overwintered under the ice in a pool no larger then a basketball court in a river that dries to a boulder field in summer.  Amazing!  : )

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Cam MacKenzie and I set out for the TOAS pool to retrieve our vertical fish antenna and the fishy data it holds.

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Still poised on the snow and ice covered lake where we left it, our vertical fish antenna continues gathering data.

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Our simplest antenna yet, this awesome fish finder pulls easily through the ice hole.

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Interested in year-round temperature conditions at the TOAS site, I redeploy our iButton data logger using a rock bag and bouy.

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Our snow machines, Thumper and Black Beauty, ready for our return to Toolik Field Station with antenna data in hand.

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Awesome snow conditions along our frozen riverbed trail provide a fun ride home.

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And… We have fish!!! Six of our tagged fish swam close enough to our antenna for us to track them and all six were Arctic grayling!.