There are a number of reasons that can be given to 'justify' hunting. Here are mine. Note that I solely hunt for meat.
1. The meat is very healthy. I would rather eat meat from an animal that has never been tainted with antibiotics, steriods, and whatever else they might put in beef. perhaps you should also research all the crap that is fed to cattle before they are slaughtered. Aside from the chemical issue, it has less fat in it and is very lean. For example bison has less fat in it than chicken and turkey. You could find this info on the net - just search for bison farms and producers
2. I consider the different lives that the animals I eat have a chance at living. I have decided that it is more ethical to hunt a wild animal which has had a chance at a free and wild life. Compare this to an animal that is bred and raised solely for the purpose of human consumption. The cattle are fed tons of crap as above, the are shipped to feedlots by stuffing them into trucks, the are stuck in pens (or whatever they are called) where their sole purpose in life is to fatten up. Then they are slaughtered unceremoniously with no appreciation from the consumer for hte life that hte animal has lived. Every time I shoot an animal I have worked for it and will continue to work to prepare that animal for my table.
The only analogy I can come up with is that this is akin to 'animal slavery'. I would rather have a free animal, that has lived a ggod life, on my plate than something that has been raised in slavery for human convenience. I argue that it is more humane and ethical to kill and consume a wild animal than one that is raised for my convenience.
3. Cattle are fed sub-therapeutic doses of antibiotics. This increases their growth resulting in a larger animal for a given amount of feed. However, these low doses do not kill all of the bacteria (E. coli) in the animals system, it just kills the weaker less adapatable bacteria. This means that stronger, more adaptable bacteria survive. Then these stronger bacteria multiply - and the bacteria in the animal are on the whole better able to survive antibiotics. Over numerous applications of these antibiotics, the bacteria in the animals system become more and more resistant to antibiotics. This plays a role in the emergence of superbugs that are restant to antibiotics. This is becoming a huge issue in hospitals and people are dying of this. This is not the sole reason for antibiotic resistant bugs but it is a contributing factor.
That's about it, I hope I did not offend any ranchers, but that's the way I feel. Further research on all of this will certainly be productive.
Good luck. I would love to see you post your paper here on the site. I'm sure you would get a lot of feedback and editing advice that make it a very concise and well argued paper.