One reason we don't have kelp forests in Oregon is due to sea otters having been wiped out, which kept the urchins at bay.[0] Unfortunately, according to OPs a

One reason we don't have kelp forests in Oregon is due to sea otters having been wiped out, which kept the urchins at bay.[0] Unfortunately, according to OPs article: Others have suggested bringing in another kelp forest predator, the sea otter, to help fight back the urchins. The problem with this appears to be that sea otters aren’t so interested in the skinny, starved urchins occupying the most barren areas, reports Anuradha Varanasi for Inverse. A separate study published this week in the journal the Proceedings of the National Academy of Sciences, suggests the otters do eat urchins but that they prefer the more well-fed residents of the coast’s remaining kelp forests to the so-called “zombie urchins” clinging to life in the denuded barrens. [0] - https://oregonwild.org/about/blog/lost-sea-otters-oregon-part-four https://oregonwild.org/about/blog/lost-sea-otters-oregon-par...