I have caught everyone of my sharks on circle hooks. For 7's I use 13/0 hooks that are about the size of 16/0 mustads used very successfully by the east coaster sharkers. I do open the gap about 1/8 - 1/4 in. On sharks with big teeth, if it doesn't set directly in the corner, it's probably getting caught between the teeth and popping loose without actually catching skin. On the east coast, when they are hunting big sharks with big teeth, the hook of choice are 20/0 which are big enough to get around the jaw bone as well if it doesn't catch the corner. I believe I am somewhere in the 90% bite to hook and land ratio with the hooks I use. Plus at 5.99 per 25 hooks, they don't hurt the wallet. Last year, most of my sharks were also on hooks with the barb pinched down. Once a circle truly sets, it's almost impossible for it to come unbuttoned unless it tears loose.
I agree with circles, it's very important how you hook the bait to allow clearance. I always use bait thread to lock my bait in the position I want so it can't rotate and get the point buried back in the bait. I have been meaning to get some picks of how I rig my bait. Maybe I'll get some up tonight.
Would love to see some pics and get a link to your source of hooks 
Ask and you shall receive........
I get my hooks from Academy.com, its a box retail/online chain back east, similar to what Sports Chalet was.
https://www.academy.com/shop/pdp/eagle-claw-lazar-sharp-circle-sea-single-hooks-25-pack#repChildCatSku=025307125Looks like they are currently out of the 13/0 size. The last time, they were in stock around Christmas, I picked up 3 boxes so should be set for a long while now. (I currently have over 100 of the 13/0)
Here are a couple of hooked bait images. These are the 2 most common ways I hook baits. I usually use macs small enough to just make 2 baits. If there is a middle piece, it is usually too small to bother with and becomes chum. Besides, I never have much luck with middle pieces staying on long and I hate wondering if I have bait still on the hook.
In this image, you can see the bait thread wrapped on the hook and around the mouth of the Mac. The way I wrap is, attach thread to hook point side of bait, wrap around 1 side of the bait to the back of the hook, around the hook shank, around the other side of bait, around the hook shank again then repeat as many times as you feel is neccassary. I usually do 4-5 complete wraps. To finish and prevent unraveling, form a loop around a finger, then twist your finger to put 3 double twists and place the loop from your finger over the point and tighten, repeat 1x and cut the thread leaving 1/2 to 1 inch hanging free.
In this photo, you can also see how I pinched down the rather large barb that this hook has. With the barb in place, It was almost impossible to rotate the hook out, With the barb bent down, but with a noticeable bump left, it was still difficult to rotate out, but much easier than with the full barb. Unless you are tying your bait to the hook somehow, I would not recommend this as it will make it much easier for your bait to unhook while sloshing around under water.
I use Atlas Miracle thread.
http://www.cabelas.com/product/Atlas-Mikes-Miracle-Thread/1166261.uts?productVariantId=2804789&WT.tsrc=PPC&WT.mc_id=GoogleProductAds&WT.z_mc_id1=03070709&rid=20&gclid=EAIaIQobChMI4fyJgPW62AIVw2V-Ch3jnwlpEAQYASABEgI5ofD_BwE&gclsrc=aw.dsTail Chunk
I start by cutting the lobes fines off the tail, while leaving the base of the tail to act as an anchor. This reduces the tail from spinning and knotting up the leader when there is current. Using the hook as a guide, I see where I will need to hook the bait and still leave the tail up near the hook eye. I proceed to hook the bait and using a small zip-tie, I zip the tail to the hook eye and tighten with needle nose pliers. I did not clip the tag end in this photo for demonstration purposes, but dont forget to clip the tag end off.
2 notes on this method.
1) Don't worry about how big of a hole you make when hooking the bait, it just to keep the bait aligned. Zip tie is whats really holding the bait.
2) Don't worry overmuch about the gap size, as long as about 1/2 is still free. It only takes a few minutes for the bait to thaw enough to not be a problem.
I have posted this up for comparison before, but will do so again since the PB devil ate the photos.
13/0 Eagleclaw L2004UH vs a quarter. (BTW this is a hook that BlacktipH on youtube has recommended)
