Yeah, no reason for him to have a knife.

Quick look at the Irish laws, and seems unclear if they make distinctions between fixed, locking and slip joint knives.

So any knife (unless its banned, like flick or butterfly knives) with a blade less than 8cm you don't need have to have a reason to carry in public.

But as a working fisherman would be good reason enough to be able to carry longer bladed knives.