Isn't there a risk of amnesic shellfish poisoning[0] in that area? Looking at the wikipedia page for domoic acid[1] Pismo Beach is even mentioned by name. Could that be part of the reason why there's an abundance of shellfish on that beach, i.e. because people leave them alone rather than risk permanent brain damage? I'd read it is a likely explanation for the incident that influenced Alfred Hitchcock's The Birds[2].

Don't want to spoil the article's analogy, although you could perhaps make a new one connecting abundance to toxicity.

[0] https://en.wikipedia.org/wiki/Amnesic_shellfish_poisoning

[1] https://en.wikipedia.org/wiki/Domoic_acid

[2] https://www.independent.co.uk/arts-entertainment/films/news/...