Switch to using a higher lb test fluorocarbon leader to prevent biteoffs.
I used triple fish brand 100% fluorocarbon line and use back to back uni knots to tie on some leader material, using in 25lb last year, 20lb this year. I've never had a bite off. Lighter test might work very well also.
I've actually been fishing northerns with soft plastics almost exclusively this year (until they went deep and I started using cranks). Northerns really love soft plastics even more at times than 'traditional' pike-y lures, and I believe they give a better impression of an actual food item than triggering a reaction or anger strike with flash, wobble, and pulsations.
The fact is that soft plastics give the impression of 'food' to visual predators, and pike will gobble them up if they are hungry.
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