There is a bit of difference between, say, the height of a given reproductive cycle and / or some complete cessation; and the woman in that article. Rogers-Bennett, was specifically interested in getting a particular "crop" of purple urchins to some arbitrary market size aesthetic, whose buyers are notoriously particular -- not that they were necessarily incapable of reproduction beforehand. Sure, there is the "primary" season in the Winter; but in Northern California, ripe animals can even be found through July and September.
Below are some visibly spawning urchins from a mid-June collection.
I have also failed to see any appreciable change to areas where culling -- legal or otherwise -- has been performed, whether through physical removal or slag hammers; and have seen plenty of young urchins, particularly off the Sonoma Coast, near Sea Ranch, whose sexual maturity commences when they reach only 25 mm.
We collect urchins almost year-long, for laboratory use -- and have rarely failed to get them to spawn, even in so-called off-months, when we would occasionally switch to sand dollars (another echinoderm order -- basically a dorsal-ventrally flattened urchin with highly-reduced spines).
Aside from chemical methods to induce spawning (injections of 0.55 M KCl, seawater, even air emboli), protocols for bioassay usage, have also encouraged, when all else fails, direct "injury to conspecfics" to induce spawning; that is to say, the use of a hammer . . .
