Photo: Len Gilday
Shores
Does Kwilákm Have Two Species of Oyster
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Pacific Oyster
(Magallana gigas)
The Pacific oyster is Kwilákm’s common oyster and a relative newcomer to our shores. Pacifics were introduced into aquaculture operation beginning in 1925 following the collapse of the Olympia oyster fishery.
Pacific oysters, originating from Asian waters and relatively tolerant of warmer waters, are expected to adapt to our warming climate. However, as seawater absorbs carbon from the atmosphere and oceans become more acidic, crabs, seastars, sea urchins and oysters are finding it difficult to build their calcium carbonate shells.
The Olympia oyster
(Ostrea lurida)
Olympias, known to its fans as “Olys”, are BC’s only native oyster. They are small, only four to six cm across, fitting neatly in the hand. They are rounder and more delicate looking overall than Pacific oysters. A typical Olympia oyster is not even a quarter the size of its bigger, non-native cousins.
Olympia oysters are not easy to discover. They generally live lower in the intertidal than Pacific Oysters, making them less visible to the casual observer.
By the 1930s, BC’s Olympic oysters were nearly wiped out through a combination of over-harvesting, shore side development (that disturbed soils, releasing fine sediments which smothered oyster beds) and poisons such as vessel anti-fouling paint and the tons of toxic chemicals dumped by paper mills directly into nearshore waters. In 2003, BC’s native Olympia oyster was added to the Canadian Species at Risk Act as a species of “Special Concern”.
Are any Olympias remaining in Kwilákm?
The Olympia Oyster Field Guide, a knowledgeable guide available from the Puget Sound Restoration Society (PSRS), offers this advice about searching for Olympia oysters: “Olys are wonderfully cryptic critters. They are not showy oysters; they do not jump out at us as we amble along the beach or even muck and poke about. In fact, they bear very little resemblance to the archetypal oyster that we have in our mind’s eye as our ‘oyster search image.’One has to be searching for Olympia oysters to find them.”
Researchers assume that small populations of Olympia oysters are currently stable at low levels in the Salish Sea. Do Olys still hang on in the Bay? Good question: much remains to learn about our oysters. Please be careful when wandering our beaches. Return rocks to where you found them to protect the homes of small creatures. Collecting or harvesting Kwilákm oysters is not allowed.