Was Steve Irwin vegetarian?

No he was not a vegetarian. In an interview with Scientific America he was asked, "Have you ever considered becoming a vegetarian?".

Steve Irwin responded, "I went through a big stage of my life where I thought, you know, maybe it would be better to be a vegetarian, so I researched it. In no uncertain terms did I research it. Let's say this represents one cow, which will keep me in food for, let's say, a month. Now that cow needs this much land and food. Well, you can imagine, that cow needs x by x amount of land, and you can grow trees in it. Around that cow, you can have goannas, kangaroos, wallabies. You can have every other single Australian animal in and around that cow. If I was a vegetarian, to feed me for that month, I need this much land, and nothing else can grow there. Herein lies our problem. If we level that much land to grow rice and whatever, then no other animal could live there except for some insect pest species. Which is very unfortunate."