First off, I am not in good enough health to help her nor do I have any experience with fishers. To date she has one cat injured and two cats killed inside the barn. The cats are barn cats and she feeds them 2X daily, and at night most of the cats stay in the barn. She read (googled I think) that a fisher makes a circuit of 2-3 weeks, she is convinced a fisher is getting after her cats. It seems to catch by back legs while they are sleeping among hay bales. The time between the first attack and the second attack was a month, in between those attacks our neighbor lost a cat (missing). It was 3 weeks between the 2nd attack and the 3rd attack. She is using cage traps and thus far has caught 2 coon and an opossum. The last cat was killed after catching the coons. She read somewhere that if you can't catch the fisher you should scare it away. The way they suggested you scare it away is to use coyote or bobcat lure. When I heard that I had to laugh, but she believes it. She wanted me to ask the experts so let me know your thoughts.

Have her take pics of the tracks in the snow around the barn...to see if it is a fisher

Also a long picture of the line of tracks...to see the gait...of said critter.

Probably have to keep at least 3 cages working.

Bait them with beaver meat...and some Gusto on a rag suspended over the trap..

Cover that trap with hemlock bows...to make a cozy cubbie type of set.

My thoughts are same as two weeks ago,
tom cat.

I could come put a trail cam out for ya to see what you are dealing with for sure.

Move the cats in the house and they will cuddle with you at night.

That's a wonderful offer and a great idea. Maybe help "adjust" what needs adjusted as far as the cage traps set up too.

I can see a big feral tom cat also. If the critter returns you can get pictures. Using coyote lure might not scare a fisher away. I have caught many fisher in coyote sets with coyote lure.