Most of the cultivated salmon is actually containing significant amounts of heavy metals (due to the sea fish they get fed). And it is also given large amounts of medication to prevent sickness and parasites. This all ends up on our plates... I love salmon, but have almost fully stopped eating it, lacking a trusted source. Also because the salmon get fed with seafish, cultivating them actually contributes to overfishing the oceans. There is a german documentary about it here: https://www.youtube.com/watch?v=8_Sl_wjiOyI
the overfishing problem you mention is also addressed in "Cowspiracy" (http://www.imdb.com/title/tt3302820/) which I highly recommend. Since few days available on Netflix Germany.
