For further clarification, one of the reason we have so many sea urchins is that humans have wiped out the sea otter population Southern California, and actively keep them from migrating back into the area. Sea otters prey on the urchins. Urchin relocation is an attempt to somewhat restore the natural balance. Sea urchin overpopulation is devastating to the kelp beds. The kelp acts as a nursery for a wide variety of other critters, and provides smaller fish protection from larger predators. Thus, kelp is vital to Southern California for healthy fisheries.