Wasn't the case when I did a run a few weeks ago. The system for killing the turtles and collecting their meat is really wonky. To kill them, get underneath (~4-5 m), right click so you're looking down the scope of your SDAR in first person mode, then fire a single bullet right in the middle of the underside of the turtle. I find that grabbing the meat works best if you stay in that first person mode and start spamming the windows key while swimming toward the meat. You might have to back up and try again, but sometimes it works right away.
In sum, I think 9Jon72's technique being poor is the most likely situation here, not that mine is perfect.