why after the death of steve irwin,are aussies killing manta rays,by cutting there tails off?

assies are killing the fish that steve irwin was killed by in a freak accident,this wont bring him back,we all knew that one day this bloke would be killed by some sort of animal,due to his insaine antics with dangerous species,it was just a matter of time.indeed he was a entertainer for the media,but i lost all interest in him when he held his baby,over a croc,stupidity at its best.RIP steve. By mal y