I recall reading either in comments to an MSM article or maybe even on WS that there was speculation that crab or fishing nets were used to lower parts into the Gulf (probably connected to the theory that one of the piers was used as a main site.) It would make sense that some parts stayed in the net(s) and others, because of size or weight, floated out. I'm sure some of the remains fell prey to the gulf water inhabitants which was probably the intent of the two sick minds who disposed of them.
As for the tattoos, I think the ones on Jaren's arm were extensive. If the plan took longer than they expected, they may have just stopped with the smaller ones knowing they were risking being seen if they didn't hurry with disposing of her remains. Ugh- I hate having to rehash the events involved in Jaren's death