I agree that trying to impact the market by restricting the supply is the wrong approach. In any open market, lowering supply has the immediate effect of increasing the price. Only this will cause the other effect, a drop in demand. But the demand will still be there.
I suggest that [ demand x price ] remains constant as long as any supply is available. Therefore, [ price = demand / supply ] Lowering supply must therefore cause a combination of an increase in price and a lowering of demand.
Your goal here is to lower supply. [ supply = demand / price ] So you either have to lower the supply, (protect against poaching) or somehow raise the price. (making export illegal, add fines and risk) They're doing both of these things already.
Temporarily inflating supply (by selling off stockpiles of ivory) causes a combination of increased demand and lowered price. Increased demand may cause problems since you can't dilute the supply indefinitely with finite stockpiles. But lowering price will impact poaching by making it less profitable for the fixed risks involved. So in the short term it will definitely help, but in the long term it may backfire when supply returns to normal and demand remains the same, causing prices to go up and poaching to pick back up.
I personally see increasing penalties as the best sustainable approach.
