Bit more than a couple of years - tuna is pretty slow growing, but yep. Worked for cod (sort of - quotas do cause their own problems). Worked for whales.
Something that actually makes sense, same as any agricultural land management program that doesn't involve soil banking or production subsidies (both of which are counter-productive and far more damaging in the long term than doing nothing.) The ocean is most definitely a shared resource and needs to be husbanded, same as anything else.