With Oceans Day taking place this month, it’s a great time to take a closer look at one of coastal B.C.’s more elusive creatures – the humble clam! These molluscs call the sandy shorelines of Mayne Island home. The native clam species found in the Salish Sea include littleneck clams, geoducks, and butter clams. Manilla clams, an introduced species, can also be found here and are commercially valuable.
Clams are invertebrates, meaning they have no backbone, but that doesn’t mean they aren’t tough and resilient creatures. Their hard shells protect them from predators such as birds and fish, while their powerful foot allows them to burrow deep into the sand if there is danger nearby. They lack a brain, but they possess a nervous system that controls their daily functions. They belong to a class of animals known as bivalves, along with oysters, scallops, and mussels. All these animals possess a shell with two halves, or “valves”, which are kept closed with strong muscles.
Clams feed by opening their shell, sucking in water through their siphon, then filtering out small bits of food before ejecting the water out of a second siphon. Clams aren’t picky eaters, they will eat anything small enough to enter their siphon, including plankton, algae, and organic matter. A large clam can filter up to 90 liters of water per day, which helps keep the surrounding waters clean and free from excess nutrients.
Bivalves are known be very long lived. Their age can be estimated using a technique that’s comparable to the counting of tree rings. A new layer is deposited on their shell each year, allowing researchers to determine their age by counting each layer. The oldest clam ever recorded was a mind-boggling 507 years old! The scientists who studied the clam named it Ming, since it was born during the Chinese Ming dynasty in 1499. To give some perspective, Ming the Mollusc was born 65 years before Shakespeare. Some scientists believe studying clams could provide answers to the mysteries of the aging process in other animals, such as our primate selves.
First Nations Context
On the BC coast, clams and other shellfish have been a critical food source for Indigenous peoples for millennia.
“Clam harvesting has been important to our people for thousands of years. I believe it is one of the unique attractions to the coastline for Salish people. All year round you’d have a very valuable source of protein, right at your front door.” W̱SÁNEĆ Elder Jim Elliot
In fact, this resource was so valuable that Indigenous peoples managed it through the construction of “sea gardens”. These structures exist all over the B.C. coast. One such garden, at 3,500 years old, is older than some Egyptian pyramids.
To build a sea garden, people placed a large wall of stones in the intertidal zone. Over time, silt and sand built up within the wall, creating a flattened terrace where clams could flourish. These gardens were located at just the right height to allow optimal clam growth. Recent studies have shed a new light on this ancient form of aquaculture. The gardens can produce up to 300% more clams than the areas nearby. This goes to show the ingenious ways in which Indigenous peoples managed the land and sea.
Lately, there has been an exciting resurgence of interest in these traditional practices, specifically in the Gulf Islands. From 2014 to 2019, Parks Canada, the W̱SÁNEĆ Nation, and the Hul’q’umi’num Nations participated in the Clam Garden Restoration Project. The project utilized scientific knowledge and traditional ecological knowledge to restore two sea gardens on Saltspring and Russel Islands. Now, Indigenous leaders are seeking approval to begin harvesting clams from these renewed gardens. This will provide a sustainable source of food while carrying an ancient practice into the present day.
Middens on Mayne
Mayne Island also contains remnants of ancient harvesting practices. If you happen to be out for a walk at the North end of Bennett Bay beach, look towards the meadow above the beach. There you’ll see a mound of clam shells along with charcoal deposits from old fires. These mounds of shells are know as middens. Coastal people used the midden material to level the ground of their habitation sites and to create beach terraces. These areas are archaeologically important, so please don’t remove any material from these sites.
Free Sea Life Presentation
Feel like learning more about clams and other amazing sea creatures? Come down to Miners Bay on June 17th from 11am to 1pm for our Oceans Day Beach Activity. A panel of experts will lead us on an exploration of the marine life in the area. Experience the wonderful diversity of creatures living along the shoreline!