Octopus houses and clam gardens: What ancient sea harvesting practices can teach us about sustainability

Most people strolling along British Columbia's vast shoreline likely wouldn't think twice if they stumbled upon low mounds of rocks while looking for crabs or other sea life.

But for those who study these formations, they represent once-thriving sea gardens Indigenous people used to harvest food and other animal products.

Kii'iljuus Barbara Wilson, a Haida matriarch and Indigenous scholar from the Cumshewa Eagle Clan, is part of a team of people working to highlight the significance of these sea gardens across the Pacific Ocean region with an online map. 

"It's time to ... learn about all the things my ancestors did to ensure that there was enough fish and octopus — looking after and respecting the environment," she said in a statement. 

"We managed to live in the world for thousands of years without the massive ecological destruction that's happening now. It's very much about not taking more than you need."

Wilson worked alongside a large team of Indigenous knowledge-keepers and scientists — including project lead Anne Salomon, a professor of resource and environmental management at Simon Fraser University — to build the detailed map and write the accompanying stories. 

The site features a combination of Indigenous stories and Western science explaining the significance of each sea garden identified on the map. 

"People learned over thousands of years how to modify their relationship with the land and the sea to not only benefit from them, but maintain those relationships," Salomon said.

From clam gardens to octopus houses, herring egg gardens to tidal fish traps, the map locates and explains the ancient tools and practices used by Indigenous groups across the Pacific region, including Hawaii, New Zealand, Costa Rica, Japan, Chile and, of course, British Columbia. 

The site focuses on the study of mariculture, a branch of aquaculture that involves the cultivation of marine life for food and other animal products in enclosed areas of the open ocean and other water sources.

Salomon says the map is used to track how Indigenous people, for thousands of years, stewarded the ocean and were able to adapt to changing environments to survive. She says analyzing these ancient practices could help people in the future face more extreme climate events and resource scarcity.

One example of this is the clam gardens located off the coast of B.C., Salomon said. The gardens are rock walls built at the low-tide line that trap sediment and reduce the slope of the beach. They date back at least 3,500 years and were used to create a better environment for clams to grow.

Salomon said the trapped sediment creates cooler temperatures in summer, and warmer ones in winter so the clams have a better chance of survival.

With the increased frequency and magnitude of events like last summer's heat dome, Salomon said innovations like clam gardens can act as a buffer against extreme conditions. 

Salomon said Indigenous groups, such as the Hul'q'umi'num' and the W̱SÁNEĆ people, are now working to revitalize clam gardens as a way to reconnect with ancestral knowledge that government policies tried to erase.

And the Haida are looking to revitalize the use of octopus houses, which are also featured on the map. The houses are built in an intertidal pond — an area in between the shoreline and a rock wall built to enclose the space from the open ocean.

They were used to trap octopuses, which would then be eaten or used as bait to catch halibut.