Hakai Magazine

Coastal science and societies

Smashing Urchins for Kelp

As they wait for sea otters to return to Haida Gwaii waters, Parks Canada and the Haida Nation take matters into their own hands to foster a healthier ecosystem under the waves.

Authored by

by Katrina Pyne, Grant Callegari, and Jude Isabella

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A very long time ago, the people living on the islands of Haida Gwaii, British Columbia, in the northeast Pacific tended a complex ocean ecosystem. They struck a balance with a voracious top predator that foraged for the same food—shellfish and sea urchins—yet whose presence kept the nearshore habitat healthy. Then came the fur trade in the 1700s.

Sea otters, the top predator, were commercially tops in the fur trade, fetching outrageous sums in China where their luxurious fur was most prized. After 200 years of plunder, the sea otters disappeared from Haida Gwaii waters—and kelp almost followed suit. Without sea otters, sea urchins preyed on sprouting kelplets, denying them their birthright to grow, reaching the ocean surface, green strands undulating side by side by the hundreds, creating an underwater forest, habitat for rockfish, brittle stars, and shrimp—a diversity of life.

Kelp barely held fast to the ocean bottom, thick with layers and layers of sea urchins. All was not totally lost for the people. Sea urchins at the feed line—the healthy ones with access to food—were full of delicious roe, aka uni. And, in a lemons to lemonade kind of move, a commercial uni industry eventually sprung up in Haida Gwaii waters.

But change is coming again. The sea otters are back in the North Pacific Ocean, establishing colonies to the north and south of Haida Gwaii. One day, they will arrive at the archipelago. But the Haida Nation, in collaboration with Parks Canada, are one step ahead of the comeback cubs.

Last summer, they launched a program to restore the kelp forest on their own in the Gwaii Haanas National Park Reserve, National Marine Conservation Area Reserve, and Haida Heritage Site: Chiixuu Tll iinasdll (Nurturing seafood to grow). To restore kelp beds, scientists have taken aim at sea urchins, harvesting the creatures at the feed line and smashing layers of zombies, the roe-less sea urchins, clinging to life by munching the odd bit of kelp until they have a chance to move to the feed line.

Chiixuu Tll iinasdll aims to reduce sea urchin density by at least 75 percent in a 20 hectare area (or, in the international language of FIFA, 28 soccer fields) in the low intertidal and shallow subtidal zones. Following the initial reduction, work will concentrate on maintaining a smaller sea urchin population so kelp has a chance to re-establish its dominance, restoring the complex ecosystem the Haida Nation began tending so long ago.