AznVinc3nt

Hook type will have an impact on your chances of landing whatever it is (I agree with @Old Scaley that a small shark or school mackerel are the two most likely options). What sort of hook were you using? I'd go to 30lb leader (you could still go heavier but the heavier you go, the less likely to land other desirable fish like snapper, etc) and try using a circle hook (around 3/0 size) as you can land them if you hook them in the corner of the mouth (just don't give it ANY slack line once hooked, and perhaps set your drag a little firmer.
As Hamish said, you could also try ganged hooks - if you go this way, with a live herring bait, I'd just use two hooks, pinning one hook lightly through the back of the hook. I'd only use wire if these options fail as it will work for sharks, but less likely to attract much else (desirable anyway).
Good luck, it's always fun pondering what the one that got away was and how to catch it next time, part of the fun of fishing 🙂.

I also agree with the above. Ive used wire before but dound that unless your targeting big tiger sharks it scares alot of fish away. I usually go over kill with sharks and use 80lb mono. But you would prob get away with 30lb and gang hooks. Gang hooks are great imo for the bigger fish

Hey AznVinc3nt
All good, I'm sure there will be someone with a bit more knowledge than me on the jetty though, I am just saying this on information I've read. 
Cheers Hamish 🙂 

appreciate your detailed response. I'll try using heavier mono next time and see how it goes. Cheers 🙂

Hey AznVinc3nt
As I have said above, it comes down to what you think it might be. I personally would go to heavier mono, as you are more likely to get a bite than if you are using wire. If you think it is something with teeth, use wire though as it will give better chance. 
If you think it may be a big chopper (tailor) or a mackerel, another tip might be to use gang hooks, especially with larger pillies. 
Cheers Hamish

Do you think a heavier mono leader will work or do I need to switch to a wire leader?

Small shark? School mackerel. 

Hi AznVinc3nt
First of all, welcome to the forum. 
I think that the fish biting you off could've been a mulloway, mackerel, ray or shark if you are casting your line out or a mangrove jack or big cod if you are dropping your line in the water next to the pylons. Saying this, I haven't fished at any of these locations - this is from reading old threads and articles on other websites.
To avoid this, there are quite a few methods. The first would be to get a heavier combo, use tighter drag and be ready if this is going to happen. The second way would be to use a light wire trace if you think it is something toothy (i.e. shark). The final way might be that when you hook the fish, make sure to pull it away from any structure. 
Cheers Hamish 🙂 

Hi all,
So the other day I was fishing off of Shorncliffe Pier using live herring on a running sinker rig (20lb leader). All of a sudden, my reel starts screaming (very light drag) and then it stopped. I reeled it in to find that my hook has been completely ripped off of my line.
This also happened at Wellington Point on dead pilchard.
 
WHAT KEEPS BITING ME OFF?
 
edit: how do I avoid this issue in the future? thanks