How about instead they normally hibernate while drifting across the voids, some die, some survive but they spread to new systems. But they have found a new way to move. Baby Kraken latch onto ships and ride with them into jump.
Your crew plot a jump. The jump feels odd, the pilot reports the ship seemed sluggish, the engineer reports the jump field is a tiny bit off. Drawing a few % more power than normal.
When the ship comes out of jump there is a strange bumping and the ship rocks. Everyone will no doubt fear a miss jump but when they check they are exactly where they plotted the jump to.
Of course the next time someone goes outside the ship and checks the hull they will be hard pressed to explain the sucker/claw marks and scratches.
Now THAT I love. Add a slight mis-jump and - if you really want to freak them out - some life support issues during the jump.
The bump is accompanied by a minor decompression in a maintenance crawlspace - later found to be caused by a tiny hull puncture where [?something?] stuck through the hull into one of the life-support lines and was drawing off water and oxygen for a week...
You could find ships destroyed by it. You could find nothing but debris that is all that remains of it, a hull section that looks like something bite it off the ship for example.
Yeah - a kraken victim's external damage won't be much different to one hit by automatic railgun fire - clearly torn up by hard impacts - but if salvage teams poke around inside they'll find something to be afraid of...
"err....have we got a manifest for the ship?"
"Yeah, why?"
"Was it carrying deepfried calamari? I mean, lots of really, really big portions of calamari?"
Trying to work out how the players, the real kraken and the kraken poseurs can all meet at the same place & same time.
Heh. Nice. It's a shame they found such a nice, well-hidden operating base.Of course once you have proof that there is no "Kraken" and that its just pirates, that is when the pirate ship is found with big chunks bitten out of it
Oh - additional thoughts for biotech; since subtle, nasty tricks are more appropriate than nukes - looking at some of the books, I note the rules for (a) the incapacitation drone and (b) the jumpbreaker missile. Both look like the sort of things one might imagine a void predator wanting an analogue of.