Welcome neighbor,
Malaga Cove is a beautiful dive site with lots of pretty fish. I hope that continues to be the case. In SCUBA diving many dive to view the very game you seek (except for lobsters). So you will understand if many divers are rooting for the fish and react to hunters rather like flatulence in church. Now if you are talking lobster, then you have lots of company, including me (ya, I know, it is hypocritical).
I know you have the right to hunt so I will only ask you observe the following unwritten rules:
1. Do not shoot or spear any fish or game that are currently being used as a photo subject (it has happened) by another diver.
2. Do not shoot any game you do not know the name of, and that you like to eat it. SCUBA divers in general really get ticked when a diver surfaces with a fish on the spear and says "hey are these good to eat?".
3. Do not shoot unless you can clearly see you target and at least 10 feet beyond the maximum range of your weapon. Just because there were no other divers (that you knew of) when you entered the water does not mean others have not joined you since you started your hunt. SCUBA divers also tend to get ticked when a spear whizzes past them because someone missed the shot and could not see them in the 10 feet or less of visibility we often have.
4. Do not forget to check around for other divers before you take the shot. The other diver may not see you and swim into your line of fire just as you take the shot. Divers tend to focus on what is in front and slightly below them and zone out things to the side and above. Divers do not react well to spears in the thigh.
5. Shoot only what you will eat and observe the DFG limits on take. There really are not that many fish in the ocean anymore to begin with.
5. Know and obey your CURRENT DFG regulations (they can and do change during the season). These are very complicated and difficult to understand. The DFG guys do enforce the regulations and the fines can be hefty. Other divers are also known to phone them if they observe someone illegally hunting or exceeding the limit.
6. Be realistic. Giant Black Sea Bass are protected species and illegal to hunt. Besides that, do you really think you can get at 400 pound fish back to shore or into your boat?
7. Remember that while you are hunting you are still SCUBA diving and must continue to obey the laws of physics.
a. You must have air in the tank to breath from the tank. Check your gauges.
b. NDL limits (depth and times) still apply.
c. Assent rates still apply even while you are chasing a fish.
Now to your question; I would recommend a camera.
