Purple sea urchins are destroying California kelp habitat.
Between 2015 and 2021, a 10,000% increase in purple urchins occurred corollary to a 90% reduction in Northern California kelp habitats.
In order to prevent urchin barrens from spreading to Southern California, tens of millions of encroaching purple urchins must be removed within the next 3 years.
However, these barren urchins contain little to no uni - a seafood delicacy- which limits their market value.
in New England:
Green urchins have been overfished.
Green sea urchins were once the second most valuable fishery in Maine. For the last two decades, these green urchins have been overfished to the extent that the population cannot recover. The inability of sea urchins to recover in New England is in large part due to crab predation. In order to repopulate sea urchins in crab dominated waters will involve introducing millions of adult urchins that are large enough to resist crab predation and ultimately sustain a future urchin fishery.
Sea urchins have a critical role to play in temperate coastal ecosystems. Urchins are the regulators of fleshy brown algae, or kelp habitat.
In addition to being home to over 1,000 species, kelp habitat can sequester 20x more carbon than the same area of terrestrial forest. However, in order for these habitats to provide these services, they must maintain the right balance of sea urchins and algae density.
In California, purple urchins create vast marine deserts and starved urchins have no uni. Uni or sea urchin roe is an expensive seafood delicacy with global market.