Maybe I can start, and then ask Doug to complement.
As a general principle, Maine's regime requires a licence to posses elvers all along the supply chain. It's that stem-to-stern kind of approach that ensures that there's an ability to control it in a very granular way.
Maine has some particular features that are really detailed. I visited Maine with the minister and Doug a couple of weeks ago. Every transaction has to be recorded as a debit or a credit as elvers pass from one person in the supply chain to another. They require that to happen, so there is that record, but there is also a record of the payment, and the payment has to be by cheque. That is an additional requirement that they have, to really ensure there's evidence. There's no cash allowed in elver sales in Maine.
Another thing they did to try to tighten the controls was to require that sales be at an establishment, a place of business that is registered. You cannot sell elver out of the back of a truck or at a wharf—it's not a wharf; it's rivers. Nonetheless, you can't do it on a river bank. Again, that is a very tight requirement.
Also, when the elvers are leaving the state of Maine, there is an export event that takes place, and that is a regulated, overseen activity. You have to apply for a permit to export elvers, and there will be an event for the export that is very tightly controlled.
There are a number of things along the supply chain, and they have, of course, evolved with time.