Oysters: Unsung climate heroes for your holiday buffet

Oysters: Unsung climate heroes for your holiday buffet
Rochelle Baker, Canada's National Observer, Local Journalism Initiative Reporter
Raymond Gravier of Sawmill Bay Shellfish unpacks oysters in the Discovery Islands.

There are moments when Steve Pocock questions the wisdom of his chosen profession as a shellfish farmer.

Picking oysters off a beach in the dead of night during a low winter tide, then navigating whiteout conditions to get a loaded vessel home to port, while freezing and weary, is one of those times.

However, his disillusionment is short-lived when he hits mirrored waters at daybreak. Odds are he’ll also cross paths with orcas, bald eagles or sea lions during the morning commute.

“Honestly, just being one with nature, for me, cancels out the bad days,” said Pocock, who has grown oysters for 15 years in the Discovery Islands, an archipelago sandwiched between the B.C. mainland and northern Vancouver Island.

A reformed cattle farmer, he’s traded cultivation on land for water.

“I’ve always loved the ocean and I like the fact that shellfish farming is sustainable and has a very low carbon footprint,” Pocock said.

Sustainably grown shellfish are ‘triple good’

Bivalves like oysters, mussels, and clams are a top choice when it comes to climate-friendly seafood, providing high nutritional value with low environmental impacts, said Nico Prins, executive director of the BC Shellfish Growers Association. Plus, cultivating shellfish actually benefits marine ecosystems.

“Shellfish aquaculture has got a triple benefit,” Prins said.

“One, it’s good for the environment. Two, it’s good for the economy. And three, it’s good for you.”

Farmed bivalves produce drastically lower emissions compared to other farmed animal proteins, research indicates.

The planet-heating greenhouse gas emissions (GHG) of beef, per tonne of protein, are 30 times higher than bivalves. The GHG footprint of chicken is nearly four times higher, and tilapia, a commonly farmed fish worldwide, is triple that of farmed shellfish.

Oysters and other bivalves don’t require a lot of energy inputs and are filter feeders, relying on plankton from the ocean, Prins explained. So shellfish don’t require feed or pump waste into the water column, sparking harmful algal blooms.

“When we talk about oysters, we often refer to them as ecosystem engineers,” he said, noting large oysters can pump and strain nearly 200 litres of water a day through their gills.

Oysters can improve water quality and clarity, filtering excessive nitrogen from sources like fertilizer or farmed animal waste along with other marine microorganisms, potentially benefiting important marine plants like eelgrass, Prins said.

Any particles not consumed are ejected in “poop packets” that fall safely to the seafloor, returning nutrients to marine sediments.

Oysters and their shells on beaches can also reduce beach erosion and provide habitat for small intertidal creatures, Prins said.

“It creates structure for invertebrates and small fish to hide in and protects them from predators,” he added.

Research is also exploring whether shellfish farming and other climate-friendly marine crops like seaweed have the potential to capture and store carbon.

Oysters nutrient- and protein-rich but low in calories

Oysters are also a great choice nutritionally, Prins stressed.

The shellfish are protein-rich while low in bad fats and calories but boast high levels of essential omega-3 fatty acids, particularly for essential micro-nutrients, like iron, zinc and magnesium.

Plus, farmed oysters and shellfish provide economic benefits and clean jobs for coastal communities facing steep drop-offs in other traditional economic sectors, like forestry and commercial fishing, Prins said.

B.C. shellfish aquaculture was worth $26 million in 2021, with oyster production generating 62 per cent of the value (about $16 million), followed by clams valued at $6.6 million.

As Canada’s largest producer of oysters, B.C. produced 8,226 tonnes of oysters in 2022, an increase of four per cent from the year before.

But the shellfish industry has plenty of room and reasons to grow, Prins said.

“While production values are increasing, shellfish farming has not come anywhere near reaching its potential as a key economic driver for coastal communities in British Columbia,” he said.

A key stumbling block is low demand locally, Prins said, noting 60 per cent of B.C. oysters produced are exported — the bulk to the U.S., then Asia — while the rest mostly feed the Lower Mainland’s restaurant industry.

It’s a curious paradox the lowly oyster is unappreciated as a nutritious, climate champion largely absent from the meal rotation in homes, but is lauded by seafood lovers on bistro menus.

“I think it’s historically been marketed as this luxury niche item you eat in a very fancy, downtown Vancouver oyster bar, which unfortunately is limiting,” Prins said.

If every Canadian ate just one oyster a year, it would represent nearly a third of all the oysters produced, he said.

It may be a question of consumer education to help people understand just how easy it is to cook oysters or clams and how versatile they are, he said.

However, many consumers appear to overestimate the risks tied to eating oysters or shellfish, Prins said.

No food is immune to the risk of foodborne illness, as demonstrated by the recent rash of serious illness in the U.S. and Canada from salmonella-tainted cantaloupes.

Oysters, like any raw meat, including beef, chicken or fish, require some care when eating and handling them, Prins said.

Norovirus or Vibrio bacteria, natural to the marine environment, can build up in oysters and cause gastrointestinal illness, so Health Canada recommends against eating them raw.

The proper handling and cooking of shellfish necessitates an internal temperature of 90 C to minimize the risk of illness.

Those who still prefer raw oysters should source them from shellfish farmers to reduce the risk since B.C. growers face stringent testing and traceability regulations, Prins said.

Despite his enthusiasm for oysters, Prins is reserved about their most celebrated benefit.

“A lot of people talk about the aphrodisiac qualities of oysters, but there is no science to support it.”

However, the merits of local, sustainably farmed shellfish as a food healthy for both people and the environment aren’t in dispute and are recognized worldwide, Prins stressed.

It remains somewhat of a mystery why farmed shellfish aren’t more popular in the kitchens of climate- and health-conscious consumers in B.C., he said.

“Yeah, sometimes I scratch my head and I don’t really understand why we don’t enjoy more support.”

Rochelle Baker, Canada's National Observer, Local Journalism InitiativeRochelle Baker, Canada's National Observer, Local Journalism Initiative

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