Last year I watched a Documentary about Dolphins getting killed in Japan. It was called "The Cove". I found it a really disturbing experience viewing this. I also found that Japan are not the only country that thinks it is OK to treat a highly intelligent being with such cruelty. The other main perpetrators are the Faroe Islands, Denmark, Norway, and a few others. The aforementioned countries appear to be the cruelest though.
These Mammals have a very high Mercury content in their bodies and its not advisable to eat them but still the slaughter continues unabated. The videos below are definitely a bit upsetting to watch.
The documentary "The Cove" is worth a watch and it is not as graphic as the vids below. It shows to what lengths the local and national authorities will go to so as to keep the secret of this barbarity.