Read an Excerpt
Salmon
A Scientific Memoir
By Jude Isabella Rocky Mountain Books
Copyright © 2017 Jude Isabella
All rights reserved.
ISBN: 978-1-77160-046-0
CHAPTER 1
The Salmon Doctors
It is usually found that only the little stuffy men object to what is called "popularization," by which they mean writing with a clarity understandable to one not familiar with the tricks and codes of the cult. We have not known a single great scientist who could not discourse freely and interestingly with a child. Can it be that the haters of clarity have nothing to say, have observed nothing, have no clear picture of even their own fields?
— JOHN STEINBECK, The Log from the Sea of Cortez, 1–2
IT'S DRIZZLY, COLD AND MUDDY, and a folding table on the south bank of the Harrison River in British Columbia is no place to perform open-heart surgery. Yet Tim Clark is attempting it. His tongue sticks out in concentration as he leans over his delicate patient, who is sucking in anesthetics through a tube down its throat. The patient's flesh is slippery, but he slices deftly into the chest cavity. Within minutes, he has stitched up the wound and handed off the patient to be carried away, slightly groggy but still kicking. Next please.
The van full of medical supplies behind Clark – gauze, forceps, gloves – is a MASH unit without a war. To the sockeye salmon resting on the operating table – a Rubbermaid container – the process must seem more like an alien abduction than surgery.
Clark is no alien, though he is Australian. His purpose is to insert a data logger into the cavity behind the gills of each fish, near the heart. Once the fish is released back into the Harrison River, a tiny computer will continuously record heart rate and temperature as the fish makes its final sprint to Weaver Creek, the natal stream where this population of sockeye will spawn before dying. Each surgery takes one to 15 minutes, depending on the fish's sex; male salmon have thicker ventral tissue and need fewer stitches to close the opening.
Clark and the rest of the scientists arrived early, in the cold mist of a September sunrise. Swaddled in fleece, rain gear and chest waders, they set up tents, tables, scalpels and tubes and waited for the fish. Then the fishers, men from the Sts'ailes First Nation's fishery program, started running the beach seine to catch patients for Clark and his colleagues.
It's high drama to watch them pull it off. They fix one end of the net to a truck on shore, the other to a motorboat that zooms across the river and loops back to shore, snaring the flopping, over-half-a-metre-long creatures. By 4 p.m., they'll have deployed the seine net eight times, catching fewer salmon as the rain stops, the sun shines, the day warms and the fish sink deeper into cooler water.
The scientists have partnered with the Sts'ailes fishers for the past six years, the fishers taking DNA samples for their own fisheries program, the scientists inserting monitors to track how fish physiologically manage to take so much punishment in their final push to keep their gene pools going. In most ways, the operation feels a lot like a traditional fish camp – except that these salmon are netted for data, not food.
Knowing nothing of seining, I jump in with everyone else to help pull in the netfuls of salmon. Being on the small side, I am the weak link in the tug-of-war. The fish slap my legs, tossing, jerking, and snagging their teeth in the netting. Standing in the midst of their thrashing gives me a sense of how powerful salmon need to be to swim against the river's current. It turns out hauling in seine nets is best left to hardier souls: I go to help Clark and a couple of graduate students. They scoop the freshly caught salmon in hand-held nets and make the transfer to the operating room's waiting area, the shallow waters at river's edge where they plop the fish into a pen. For a while, I stand thigh-deep in water and write down tag numbers as the scientists evaluate each fish, plucking off a scale to send to a Department of Fisheries and Oceans (DFO) temporary lab at nearby Weaver Creek.
Sockeye populations can be identified by scale patterns viewed under a microscope. Within an hour of sending the first catch, the lab, set up just for this purpose, calls Clark to tell him that 11 out of the 25 are Weavers; the rest are Harrison River fish. This distinction matters. Clark's study compares fish physiology among different populations within the sockeye species. The focus of the study is Weaver sockeye, not the more plentiful Harrison River fish.
Humans have known, through observation in the ancient past and through experimental science today, that the more salmon runs there are, the healthier the species is overall. Whatever challenges salmon face – climate change, disease, industrial pollution, overfishing, hatchery production, fish farms – they will ultimately evolve or go extinct, depending on their diversity. Yet scientists are forced to prove over and over again, in deepening detail, that a species is doomed without population diversity. This is especially true as the climate changes and waters warm. The work that Clark and his colleagues do shows the fine, unseen differences among sockeye populations. It should be simple. But it isn't simple because our relationship with sockeye is overwhelmingly about money. And there is nothing simple about money.
The 150-metre stretch of land along the Harrison River where Clark and the others conduct fieldwork belongs to the Sts'ailes First Nation and is called simply "The Park." Roughly five kilometres from the Fraser River, it's one of the most productive fish habitats in the Fraser Valley. All five Pacific salmon species – pink, chum, chinook, coho and sockeye – swim these waters, traditionally running from June to March. Even today, after years of commercial fishing, logging and industrial pollution, the ecosystem erupts with life. The fish attract loads of birds. In the next couple of weeks, the Park will swarm with teals and other ducks. During the past six or seven years, cormorants have made a big splash here too, the Sts'ailes say, gobbling any fish that fit into their bills, including one-kilogram trout. An occasional sea lion has been glimpsed trolling the Park, having travelled 15 kilometres from the Pacific Ocean.
Clark's riverside heart-surgery project is one of many in-depth sockeye studies in Canada. Fish biologists Scott Hinch and Tony Farrell at the University of British Columbia in Vancouver and Steve Cooke at Carleton University in Ottawa manage most of them. Lift the lid on their research and it's like picking up a patio stone and seeing a colony of ants at work, all frantically moving toward individual goals that converge on a single purpose: to understand the physiology of salmon in excruciating detail. No function goes unnoticed, it seems, from heart rates and temperature tolerance to aging.
A few strides away from Clark's station, one of the younger team members, Samantha (Sam) Wilson, stands under a tent and eviscerates dead sockeye, plucking out their brains and hearts. She flash-freezes the organs in liquid nitrogen and stores them in a cooler to be couriered overnight to Ontario. Wilson, an undergraduate student at Carleton University, is intrigued by a question of colour. She wants to know if brighter-coloured salmon age more slowly than dull-coloured salmon. A salmon's bright-coloured skin comes from carotenoids (antioxidants) in the food they eat. It's possible that brighter–coloured salmon (with higher antioxidant capacity) are better at preventing aging. It's possible that they survive longer on spawning grounds. If so, do they pass their antioxidant capacity to their offspring? The question arose from studies showing that birds with bright-coloured beaks tend to have higher antioxidant capacity and stronger immune functions than birds with dull-coloured beaks. And the brighter the male beak, the more likely he is to interest a female, the implication being she will have healthier offspring if she goes for flash.
Wilson expertly cuts into a fish brought to the operating table by Graham Raby, who is charged with giving Wilson fresh kill. Raby, a graduate student at Carleton, evaluates Fraser boxes and fish bags. Fraser boxes are used by commercial fishers to revive fish nabbed as bycatch, nontargeted fish caught in the seine net. The boxes are painted black to soothe the accidental catch, and fresh water runs through them. Fish bags are essentially black duffle bags with mesh at each end, a low-tech method that conscientious sport fishers use to accomplish the same end – something they're not required to use – yet. But Raby doesn't use these tools to revive and release accidental catch. Instead he attempts to revive his sockeye – and makes notes on whether he succeeds in reviving them – then bonks them on the head and brings them to Wilson for her study. The sockeyes are slippery and strong enough to launch a heavy lid off a Fraser box, so Raby weights the boxes with large rocks. Holding down a sockeye and administering a deadly blow on the first swing is tough, but Raby is quick and efficient.
At this point, after six years of study, this group's focus has been on stress physiology and the effects of temperature, particularly the effects of warming waters. The conclusion, so far, is what one might expect: fish that experience high temperatures naturally are better at coping with stressors under high temperatures than fish that experience cooler temperatures naturally. It's a bit like comparing Vancouverites on dry, 30°C days to visiting Torontonians. The Vancouverites are wilting, while the Torontonians are delighted to have escaped the humid heat back home. Although it's not exactly the same. We warm-blooded humans can handle it even if we don't like it. Cold-blooded salmon can't.
At 4:00 p.m., the buzz of activity is muted at the Park. The fishers are packing up their gear and the catch at the lab tents is dwindling. A warm breeze carries a sweet, hay-like smell from the grassy riverbank to overlay the odour of blood wafting from Wilson's fish morgue. She has placed 28 salmon brains in vials today for transport and later study. I imagine a FedEx delivery to the wrong doorstep, someone expecting smoked wild sockeye fillets, not raw fish brains.
At the surgery table, Clark continues at a feverish pace. "It's a girl," he calls, incising a belly with quick strokes. He inserts a data logger, encased in the same silicone used in biomedical implants for humans. Clark often adapts the tools of medical doctors for his fish studies. In his lab he has a meter originally intended to measure hemoglobin levels in human blood. He has recalibrated it for fish blood. Likewise, to count fish glucose levels at the lab, he uses a glucose monitor developed for diabetics.
The implant he has just inserted in the female sockeye will rest against her organs, and the tiny computer inside it will record internal temperature as well as electrical pulses from the heart. Once patched together, she'll go back to the temporary pen in the river for a few hours before she's let loose to find her natal stream. Not a single fish of Clark's has died since I arrived at dawn. They will live to spawn and then die. Naturally.
In a few weeks, Clark will go to Weaver Creek to find his tagged fish and remove the computers. The data should tell him if the Weaver fish look for the cool spots in rivers – called thermal refuges – to save energy. It should also show him how the fish allocate energy during migration. "No one really knows that," Clark says.
Erika Eliason does similar fish physiology work to Clark's, but she doesn't contend with seine nets and river currents. A few weeks before tagging along with the crew working on the Harrison River, I drove down to see Eliason at the DFO lab at Cultus Lake, about an hour's drive east of Vancouver. All of the researchers at Cultus Lake, the same scientists at the Park, put in long summer days on fish studies at the lab, and though the setting is tame, the work is in many ways as strenuous as hauling nets on the Harrison River. The lab includes freshwater pools that dot a fenced, concrete area. At one pool, "chasers" take turns using their arms to churn the waters. The object of their flailing is a single adult sockeye, caught from the lower Fraser River a few days earlier.
To "chase" fish, you need a stopwatch, knee pads and lots of energy, particularly if it's a hot day. The chasers – four women, in this case – whip up a froth in the pool as another watches, a stopwatch in one hand and a clipboard in the other. "Way to go!" she calls, like a coach at a kid's soccer game. "Keep it up, keep it up!" After three minutes of being "chased," Eliason holds the fish up in the air to simulate what happens when a fish is caught. Then she places the stressed fish in a pool next to the one from which she plucked it, where its stress levels are monitored. The water temperatures in the pools range from an ideal 16ºC to a worrisome 21ºC. This one is at 18ºC. The group will do this for 12 fish. As in Clark's fieldwork, a few questions are in play: How well do stressed fish recover? Does temperature matter to recovery? Does handling the fish change the aging process, making them less likely to reach their spawning grounds?
Everyone breaks for lunch and I follow them to a bungalow, a home they share for most of the summer as they conduct their fish studies. Eliason sits on a couch, seat cushions caving in with age, holding a coffee mug. She is cruising toward the conclusion of her PhD and is here to help fellow students with whatever needs doing, whether chasing fish, recording data or teaching fish surgery. I have 20 minutes to interview her, which is perfect; it's like sitting through a private TED Talk. Eliason could make an 8-year-old care as much about Fraser River fish distinctions as they do about superheroes.
If things get too warm, Eliason explains, some sockeye populations are likely to die of heart failure during their heroic journey to reproduce. "It's such a narrow part of their lives," she says. The migration lasts two to four weeks, but it's critical to the survival of the species. In general, migrating sockeye suffer when temperatures are above 18ºC, she says, but not all sockeye populations will suffer equally. Each population, though the same species, is adapted to a specific river ecosystem.
The Fraser River sockeye populations are as diverse as the First Nations Peoples – and the early settlers – who could wrest a fortune, or not, from the mighty river. Whether they toughed out the climate and stayed or failed and moved on, the people left their names with the rivers the fish still swim: Stuart, Nechako, Quesnel, Chilko, Adams, Weaver and Gates.
The Chilko – historically about a quarter of the Fraser River sockeye run – are the elite athletes, physiological freaks with big hearts, incredible oxygen uptake and an ability to swim powerfully in waters as warm as 22ºC. They start to lose steam at warmer temperatures, but they're still moving at 26ºC. At the mouth of the Fraser River, the Chilko swim through warm summer waters, but by the time they've made their way up the river, they're cruising comfortably through chilly currents to their home 650 kilometres upstream, the glacial-fed Chilko River. They can handle the cold and the heat.
Nechako salmon migrate farther than Chilko – more than 800 kilometres up the Fraser River – but in water without temperature extremes. Heat the water up to 20ºC and they stop swimming. They have the aerobic scope but not the heart of the Chilko. And Weaver sockeye, which travel a mere 100 kilometres or so to spawn, are the skinny weaklings on the beach. They have neither big hearts nor the Olympic athlete oxygen uptake. Compared with the mighty Chilko, they would have a tough time adapting to a warmer world.
It took Eliason three years to figure out these differences. She spent many evenings inserting catheters into sockeye and taking blood samples as they swam in fresh water pumped into big swimming tunnels made from PVC piping at the Cultus Lake lab. The goal was to compare how well they took up oxygen from the water to feed their muscles, both at rest and while swimming; this is what she calls "aerobic scope." She was also measuring how well they pumped blood around their bodies and their heart size. As she monitored the fish, she tweaked the water temperatures.
"Every stock is different," Eliason says, waving her coffee mug in the air. "The same rules aren't going to apply." Eliason keeps saying the same thing in different words. It's as though she's in a race to understand the breaking point of each sockeye type before the fish are destroyed. More importantly, she's in a race to make the world understand it and change its practices accordingly. "How is that [understanding] going to be put into practice when they're all in the river at the same time and you can't see who is who until you look at the DNA?" I ask. She shrugs and shakes her head. Best not to think about it too hard.
(Continues...)
Excerpted from Salmon by Jude Isabella. Copyright © 2017 Jude Isabella. Excerpted by permission of Rocky Mountain Books.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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