fish finders in kayaks

do you have to have a fish finder in a kayak when fishing.ill be spinning for bass ,pollock ,mackeral and maybe some fly fishing for the same speices and maybe some drifting just outside the surf for bass and flatties

Not for what you want to do. If you use watercraft then you are the fish finder
Also no need for a fishfinder to find the mackerel in the summer

thanks i ll just use the eyes in the sky the gulls