If the reef is home to resident Reef Sharks, Nurse Sharks, Eels, and/or Goliath Groupers that have been fed, or that are commonly fed by divers, they will be all over the hunters in a flash. I've cough just one little lionfish, 2" long, and less than a minute later, its like someone rang the dinner bell.
Now, if the reef is one that is home to critters that are not being fed, you won't have a problem.
When lionfish hunting, it's good to:
Ask dive operator to take you where people hunt.
Do it as a team.
Recognize Lionfish habitat and preferred hanging spots.
Keep an eye on your buddy and on resident wildlife.
Stop if sharks get too inquisitive.
Have an inflatable smb on the Zookeeper tube, and use it if necessary, float your catch out of the way.
Stay calm, cool and collected. Most of the time, a shark or an eel is just curious and will look and move on. If they get too close, it's best to stop and find another spot or float your catch. Never leave your catch at the bottom.
Build an image, a silhouette, a pattern in your brain, so you can spot them. They blend very easy, the shape, the pattern, the typical way they move, any slight movement will help you spot them.
Another thing to keep present is that there are reefs where shark sightings are rare. I've cought lots of lionfish in Boca and Fort Lauderdale and never seen a reef shark or a bull shark. The dive operators know. Now, Palm Beach, Jupiter and Martin County have lots of sharks.
Lionfish that survived a previous attempt will take off as soon as they hear you, or feel that a diver is approaching. They will hide in a deep recess, or take off so fast that you won't be able to follow it.
If the current is strong, Lionfish hide. They don't like it. You will find them folded and resting encroached into a sponge, under a ledge or a coral head, downstream of the current.
It the current is mild, they will be floating a few inches above the bottom, or under ledges, staying stealth and ready to eat something. They are easier to catch in the morning, or before sundown.
Lionfish that are just hanging around can be cought if you have a calm, cool and collected strategy. Keep buoyancy and start taking one at a time, with minimal noise and minimal disturbance to the sea bottom. Start with the one closest to you, methodically take your time and then go for the next, but keep calm. It's critical to stay very calm and collected, otherwise, they will be spooked and flee. If you move too much, they will flee.
I try not to look at them directly in the eye, just kind of look a bit to the side... If you look at them in the eye, they will figure it out and will take off. Aim for the head. A head shot is best.
They will change color instantly, if it's a head killshot. The fillets keep nice and clear of trauma too.
Most of the time, you have a second chance for a shot, it the first failed, or if the lionfish pealed off the tip. If you need to try a third time, it's going to flee, and you will bag it if the first or second shot injured it to the point it's not able to respond.
I've been hunting and some photographers in the group have returned to the boat fascinated by the great shark photo opportunities they saw; however, we've been close, very close, but not seen a shark that same dive. Sometimes remoras will show, get close and start wanting to hang around us, so I look at my wife and she looks at me and I know we are both thinking.... hey remora, where did you leave your shark?
So, the takehome message is, go where people hunt, with operators that know. Don't feed the wildlife, go with a good buddy, keep calm, keep good buoyancy and practice, practice, practice.
Sorry for the long post, but just want to share some insights.
Cheers