To control mink you need a long term plan, using a large area to monitor and live catch, I completed a five year mink reduction for a group of farms and it was a great learning curve you clear an area just like foxes and like a bowl of marbles you take the ones out the middle and it fills up again
Best way is to find the high traffic areas over a bigger area you can and put in sand traps to get a number and also to correctly ID what you have on the ground, live trapping is the best by far and most humane and selective as you will catch moorhens and voles.
If your serious about cleaning the ground up, there are plenty of plans for floating mink traps for monitoring and setting to catch eliminates some non target species as well which is good
Best average bait I used a frozen small trout with the black and white magpie feathers hanging off and fluttering inside cage or /and little tin foil rattling around , mink are opportunists, they hate magpies love fish and just like a jackdaw they can’t resist a bit of bling to fire up their velocity of hunting.
If you can put out a stealth video camera you’ll see why they can kill and clear most ground dwelling animals and birds in an area so quickly, I’ve seen them in packs clearing up ducks in the water
You may have missed this season on the breeding season but get it right you’ll make a massive difference to next year
Good luck it’ll be worth it
