The Salmon Debate

By September 17, 2014 No Comments


Vexing and heated is the question of salmon. The reasons to eat it are many, and obvious: For one thing, it’s a delicious, very versatile fish to cook; adaptable to myriad methods of preparation (grilled, baked, pan fried, deep fried, stuffed, planked, smoked, cold-cured … the list goes on), and undeniably healthy, as a source of high-quality protein, vital omega 3 fatty acids, and anti-oxidants.  (Mind you, these days everything short of used tires and roofing nails seems to be marketed for miraculous “anti-oxidant” qualities.  I haven’t noticed anyone rusting lately, and so am somewhat skeptical. We’ll look at the whole “oxidant” question in a future issue).

Reasons not to eat it are also numerous. Salmon are carnivores that function high up the food chain. Like all top predators, that means they accumulate and concentrate toxins and pollutants from their environment. Heavy metals (such as mercury), complex hydrocarbons (such as PCB’s and all their friendly relatives), and even pharmaceuticals, hormones and pesticides from human and agricultural waste run-off enter the food chain in trace amounts, lodge in the fatty tissues of growing salmon, and, in the wrong waters, result in a menacing meal. The spawning cycle makes them highly vulnerable to environmental degradation: logging, dams, mining effluents and other pressures the water table have placed certain species and breeding populations at risk of collapse. Over-fishing in ocean waters adds to the problem.

So what is one to do? Is it possible to enjoy the nutritional and sensory benefits of salmon without contributing to the destruction of the species, or oneself? Two possible sources of the fish present themselves: farmed salmon is touted by proponents as a way to harvest without adding pressure to vulnerable wild fish stocks. Wild-harvest salmon is lauded as a more natural, healthful seafood alternative that sidesteps the pitfalls of industrial fish farming. Each presents unique challenges, and potential solutions. It is possible to combine specific species of sustainably caught wild salmon with certified, responsibly farmed fish in such a way that the impact on health and ecosphere is minimized. Assessing how to do so requires first understanding the potential problems.


Down on the farm.

The most contentious option is farming.  The method was first introduced by Norwegians, and has since grown to a multi-billion dollar industry world-wide.  Canada, with its expansive and (largely) unspoiled coastlines is a world leader. Schools of salmon are raised in pens (net enclosures) suspended in open waters, fed until maturity, then harvested, processed, and distributed.  Atlantic salmon grow to maturity fastest, and so are the favoured species.  The millions of tons produced annually support a level of  global consumption that would decimate wild salmon stocks.  It seems very elegant:  abundant, inexpensive protein from the sea without the destructive and often short-sighted interventions of a commercial ocean fishery that seems beyond effective regulation (just ask an East Coast cod fisherman, if you can still find one).

Time has revealed some unplanned, inelegant consequences.  Four basic problems combine to make farmed salmon a less-benign food source.  They can be grouped as: 1) parasites and disease, 2) environmental degradation, 3) feed, and the associated impact on wild fish populations, and 4) genetic contamination.

#1. Parasites and Disease

Parasites and disease are a problem in all kinds of animal husbandry; fish farming is no exception.  The best-known affliction is sea lice.  These parasites affect the health and growth of the farmed fish, and, even more seriously, jump readily into wild salmon populations that pass through waters surrounding the pens.  Juvenile salmon are especially vulnerable if they pass through affected waters on their way to open ocean as part of their life-cycle.  A lice infestation can and does decimate a whole generation of wild fish (the recent collapse of the Fraser River Sockeye run is thought to be connected to farm-borne sea lice).  Over-crowding in pens increases the risk of wide-spread infestation, as well as mortality rates from other afflictions (fungal infections, for example).  Industrial fish-farmers counter the threat much the same way industrial-scale farmers on land do … better living through chemistry, in the form of antibiotics and pesticides applied through feed, and to the waters surrounding the pens.  The “go-to” solution for sea lice is called SLICE (emamectin benzoate).  It’s an anti-parasite compound.  It’s effect on human health is as yet not fully understood, but has been approved on an “emergency” basis by Health Canada in aquaculture.  The handling instructions for it’s use in land-based agriculture make for somewhat alarming reading.  Like copper sulphate, used on many fish farms to keep nets clear of algae, and canthaxanthin (a carotenoid that promotes an attractive “pinkish-red” colour in farmed salmon, and is best known as a product used in the human tanning-booth industry that is now banned in Europe (but not North America) because of possible impacts on retinal health, and eyesight, generally),  it’s not something any sensible person wants on their plate.

The only sustainable, healthy solution to this problem is to avoid it.  Some responsible farm operators are taking pains to locate their pens in deep open ocean locations that are away from the migratory routes of wild fish, and strictly limit the number of fish in a given pen to reduce the likelihood of infestation.  Independent third parties monitor these measures, and can certify that the resultant harvest is free from chemical intervention, and (relatively) unlikely to contaminate wild stocks.  In the unlikely (less than 5% of the time, but still possible) event that infestations do occur, SLICE and similar products can and will be used, but the harvest will not be certified. Instead, after diversion to other processors, it becomes somebody else’s problem.

#2. Environmental Degradation

Environmental degradation is, essentially, a question of waste.  Solid waste (fish manure, to you), and uneaten food pellets settle under salmon pens to form nutrient-rich layers of sediment.  This can promote the growth of kelp and other aquatic plants that provide fodder and shelter for the whole food chain.  If the concentrations are too high, though, especially in shallower, warmer waters, the result is instead explosive algae blooms.  Sometimes these are toxic (think Red Tide), with obvious consequences.  Mostly though, the algea just grows wildly, then dies, and in decomposing  draws oxygen from the water, chokes off other plant growth, and can ultimately produce areas of “ocean desert” where few if any species survive.  Release of untreated effluent and agricultual run-off  by humans has created similar conditions throughout the world ( Halifax and Boston Harbours, and portions of San Francisco Bay and the Yangtze River Delta  spring to mind). Planet Friendly it is not.

Deep ocean farming helps mitigate the problem, as does locating pens in areas swept clean by strong ocean currents that disperse the waste.  All open water fish farms, though, by their very nature, affect the nutrient balance and thus ecosystem of their surroundings to some degree.

#3. Feed

The role of feed in assessing fish farming’s impact is only now becoming understood.  As carnivores, salmon eat other fish.  On the farm, what they eat is fish meal … that is, food pellets that are made up of other fish, ground up.  The source of that fish meal is crucial.  The general term for “meal” fish is bycatch … species of fish that are otherwise not commercially viable, and can be caught in abundant, inexpensive quantities (it takes at least 2.4 pounds of by-catch to produce one pound of farmed salmon, plus another pound or so of herring, anchovies, or other small fish rendered up for fish oil added to the pellets).

Unfortunately, those abundant, inexpensive fish species also provide the foundation for the entire marine food chain.  Removing them in bulk impoverishes feed stock for wild species, and generally involves harvest techniques that damage crucial near-shore and inter-tidal ecosystems.  Replacing fish protein with the by-products of land-based industrial meat farms adds concerns about drug and hormone supplements to the mix; battery-fed chicken meal isn’t a comforting substitute.

A responsible alternative is to use scrap from harvested fish.  Sustainable farms are adopting recovery methods that divert fish protein that would otherwise be discarded by  processing plants to produce nutritious feed.

#4. Genetic Contamination

spawn_atl_salmon90210Genetic contamination is a hot button issue.  There are “escapes” from fish pens almost weekly, as big waves, storms, or poor maintenance allow  mature fish to break free into new environments, and join the local population.  That’s not a desireable result; introduced, foreign species have a long track record of displacing natives, especially when (like the farmed Atlantic variety) the foreigners mature more quickly, and are more likely to spawn successfully.  The recapture rate from penned salmon escapes is lamentably low (less than ten percent) … it is, after all, a big, wide ocean out there.

Genetic modification is also a concern.  Modified salmon aren’t on the table yet, but research into fancy designer fish is being enthusiastically pursued.  When those varieties get beyond the lab into open water pens, escapes are probably inevitable.

The only viable solution to this concern (and the others cited) appears to be closed-system farming, in which the fish are raised in an isolated space, with waste water filtered and treated before moving onward.  Nothing escapes, and all inputs can be controlled.  The method has been used with great success for many smaller, fast-growing species (especially fresh-water fish).  As yet, the technology involved (size and scale) is still prohibitively expensive for commercial salmon production.


All at Sea.

Wild-caught salmon are an abundant resource. They spawn prolifically, renewing their populations and providing vast numbers of tasty offspring every year. When harvested responsibly (through traps, or targetted line fishing), wild salmon offer an attractive choice. Gill neting, long-line trawling, and inappropriate harvest times, on the other hand, are cause for concern. So too is the location from which the fish are caught (you can catch salmon off Three Mile Island … do you really want to eat them?).

For a responsible consumer, the key is an awareness of the species and season of harvest. Five species are in play: Pink Salmon have a two year life-cycle, and their population is generally robust. Spring and King Salmon (a.k.a. Chinook, mainly from Alaska and the Yukon) are also thriving. Sockeye and Coho salmon, on the other hand, are under threat, over-fished, and the product of river systems (the Columbia, and Fraser) that are under environmental pressure. Sockeye is probably the tastiest and most healthful species available to the North American palate (deep red, high in Omega-3, firm, and a mighty fighter when on a fishing line) but consumers should realise that they come from a dwindling stock, and need a few years of stewardship to re-establish their numbers before they’re a guilt-free pleasure. Warmer water fisheries like those in California are facing their second year of a closed salmon fishery because of decimated spawning stocks; global climate change, apparently.


Can we eat it?

So, what’s the bottom line? At this point, wild-caught salmon from responsible sources are your best bet for dining pleasure. Off-season, or at times of scarcity, farmed salmon is an attractive alternative, but only if it can be clearly certified as drug and hormone free, from low impact alternatives.  To date, only European Organic organizations have addressed this issue (Biosuisse (Switzerland), Naturland Verband (Germany), or Soil Associatin, UK). That’s why we sell you farmed Irish Salmon and Sea Trout.  In British Columbia, the “organic” label for farmed salmon no longer exists, and won’t until proper standards are established. The USDA will certify farmed Organic Salmon from the West Coast (including BC-farmed salmon that is landed and processed on American soil), but we look forward to some clarification as to whether those fish can be truly described as “drug and hormone free.”

Meanwhile, we’ll provide you with seafood, either wild-caught, or organic, that can be cooked and served with confidence. Look for the green light from the organizations below, and dine well.


The leading organizations certifying Sustainable Seafood

  • SeaChoice Canada was created by Sustainable Seafood Canada and is comprised of the Ecology Action Centre, the Living Oceans Society, the Sierra Club of Canada, the Canadian Parks and Wilderness Society, and the David Suzuki Foundation.  SeaChoice has created a wallet card that helps people make sustainable seafood choices. The card is divided into three sections – “Best Choice,” “Some Concerns,” and “Avoid” – with a list of corresponding species. We recommend this card as the first place to start; of course, the next move is yours… ask questions!
  • OceanWise is a Vancouver Aquarium conservation program created to educate and empower consumers about the issues surrounding sustainable seafood. Ocean Wise works directly with restaurants and markets, ensuring that they have the most current scientific information regarding seafood and helping them make ocean-friendly buying decisions. We are proud partners with OceanWise.
  • The Environmental Defense Fund publishes a Pocket Seafood selector and many recipes for sustainable seafood.
  • The Marine Stewardship Council is an international non-profit organization that runs a certification and eco-labelling programme for sustainable seafood.
  • Green Peace