Kelp Forests and the Purple Urchin

Kelp Forests and the Purple Urchin

The kelp forests are a key component of our Pacific coast near-shore ocean eco-system. Among their many benefits are providing food and shelter for a variety of fish and invertebrate species and sequestering carbon dioxide from the atmosphere. Currently this eco-system is in a state of imbalance due to a rapid increase in the purple sea urchin population. Purple urchins are smaller than red urchins, which historically supplied uni, or urchin roe, to restaurants and seafood markets around the world. In 2013, the sea-star wasting disease began virtually eliminating the last major predator of the purple sea urchin, the Pycnopodia Helianthoides or Sunflower Sea Star. Due to this rapid increase in population, the kelp forests began to be eaten down at an alarming rate creating “urchin barrens” where the kelp forest has been drastically or completely decimated. Urchin barrens were first noticed in California’s near shore habitat and have been moving north into Oregon’s waters. When urchins devour kelp forests and food supplies disappear, they can enter a low metabolic state which allows them to survive long periods without eating. Urchins become emaciated and nearly hollow, often referred to as “zombies” and they diminish opportunities for kelp forests to recover.

Tim collecting urchins.

The Oregon Kelp Alliance is working with a group of partners including state resource managers to monitor and control the growth of purple sea urchins in certain areas to improve the health of the kelp forests there.  One method that has been employed successfully in California is a culling or removal of the urchins by hand through the efforts of recreational and commercial divers. Other efforts include shore based aqua culture which take urchins from barrens and bulk them up by feeding them in sea water filled tanks, then introducing them to market for uni.

To learn more about ORKA and what they're up to, visit


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