Back on November 14th, when ZEC was $100, I called a $30 bottom for ZEC in the coming months https://forum.zcashcommunity.com/t/zcash-price-rebound/8370/3?u=vgm.
This happened because ETH miners who switched to ZEC early on have migrated back to ETH mining due to higher profitability. This removed the huge selling pressure from ETH miners converting their ZEC to ETH. The majority of remaining ZEC miners are probably using older AMD cards (280, 290, etc.), which have comparatively poor Ethash performance and therefore ZEC is still more profitable for them.
Now I believe ZEC will stabilize, but there will be no bull market just yet. The price of ZEC is inextricably linked to the price of ETH. When ETH breaks out to new highs later this year, we will see the ZEC price move higher.