If you eat prawns, you are directly contributing to the slave trade in most cases:
External Link/Members OnlyIf you drive a car or use energy, you are partipating in the destruction of the environment.
If you use a computer or an ipad or an iphone, you are holding a device made in a chinese factory with conditions so poor they have to install nets to stop people committing suicide in their lunchbreak, using rare earth elements mined by children in war zones.
If you consume anything with palm oil (processed foods, cosmetics) in, you have helped eradicate rare creatures by the removal of their habitat to make way for plantations.
The horrors of meat "industry" are well-documented.
Most things in our comfortable western lifestyles cause harm to some other living thing. Depending on how bothered we are, we take steps to minimise that harm. Beyond that, the only solution is to go and live alone as a hermit, growing all of your own vegetables and wearing hemp. In my opinion, beyond taking precautions to avoid pimped girls, and possibly anonymously reporting people you meet who aren't trafficked, there are greater steps you can take to reduce the amount of suffering you cause in the world.
Strangely, I haven't seen any of the "anti" brigade who preach abolition to stop slavery from advocating the banning of prawns anywhere.