For some older people (like me), or people with slow reactivity, these dredging 'minigames' are unplayable. And so the whole game becomes pointless. Shame to the dev for giving no warning.

Maybe you've already tried this, but I think the speed of the mini game can be slowed in the setings menu. Ihope this helps.

Yes, I have set it to slow. However, sometimes still a bit too fast for me, esp. the dredging. I started to go with the rhythm of the ups/downs, that helped a lot.

There's a relaxed fishing option. It keeps the cargo from lowering when you hit the gaps so at least you don't lose progress. Essentially don't press the button at all and it will eventually succeed but you can still try to avoid the gaps and succeed a little faster.