The global demand for capers is approx. 18,000 tonnes. This year about 15% (1,200t) less was harvested in Central Asia (Uzbekistan and Kyrgyzstan) and just 1/3 of the regular season in Iran. Resulting in approx. 2,000t less being available in these territories and the shortage being most serious with the large calibres. The large sorts are also lacking in Morocco and Syria. About 20% or approx. 3,500 t less in total is expected to be available from the current harvest.
On the other hand, there is still leftover stock from the 2017 harvest, which will probably balance out the quantities. 
The closed caper buds are picked by hand in spring and are inedible raw. They are tumbled for a day first and then preserved in brine and vinegar. 
This is how the capric acid and glucosinolates develop that give the capers their sharp, tangy flavour. Capers should be closed, olive to blueish green and as small as possible. 

Capers are divided into different classes depending on their size in France: 

„Nonpareilles“ (4–7 Millimeter)
„Surfines“ (7–8 Millimeter)
„Capucines“ (8–9 Millimeter)
„Capotes“ (9–10 Millimeter)
„Fines“ (12–13 Millimeter)
„Hors calibres“ (13–15 Millimeter)