Although like Aquabell I'm not exactly a fan of mono traces for 'toothy critters' much preferring wire I just wanted to recount an experience from the mid-80s in the Azores. It certainly confirms the 'never say never'.
Anyway the Blue Marlin fishery off Faial had just been discovered and together with a couple of friends we'd been fortunate enough that our chartered local boat was out of commission. It had tangled a rope around both props and distorted an 'A' frame. Fortunate? Well a famous 44' Rybovich, Double Header, had just been shipped over from Palm Beach and, before the owners arrived, the crew were desperate to do some exploring. They just want someone to 'crank the handle'.
So one afternoon, and I'd already released two Blues, they decided they wanted to try for Swordfish. We ran 40 odd miles to a bank in 280 fathoms of water off the neighbouring island of Sao Jorge and within an hour one of my friends had taken a small Broadbill - the first ever I understand that had been taken sportfishing from the Azores.
Then my bait, a dead 'Boston' Mackerel - yes, they'd even brought iced baits from the 'States - fished at 150' got taken. The crew were convinced it was a big fish and got out the 14" back banded gaffs. Using relatively light drag pressure I worked it to the surface ... the crewman took the mono leader .... and then started to laugh. Why? On the end was a Blue Shark around 140lbs and, despite their incredibly sharp teeth, it had failed miserably to bite through the mono. Denis yanked the leader from side to side across those 'razors' before it eventually bit down and cut through it.
So the moral? And linking it back to your Bluefish encounters. Even though I was using 80lb class tackle it was with limited drag pressure and smooth pumping and that fish, I suspect, never really realised it was hooked. So light drag pressures and smooth pumping coupled with a heavish flurocarbon trace might, if all else fails, work with those Bluefish. They tend only to jump and shake their heads - and teeth - with heavier drag pressures and that in itself will shear through mono.
Back to the beginning though I'd still suggest that 6 inches of light wire attached with an Albright, rather than a swivel, to your reel line.