make visible fish, you can spear, but if you get close they disappear swiming away. so if you want to get really large fish, you will have to use a rod and some skill.
make fishing a fun minigame, where you need ro reel and feel the tension aswell as pull the rod. if you go too far, it will cut the line and you will need to spend some bone or metal to make a new hook.
larger fish will give you more food and fat aswell as maybe a random chance of an item iside of it, an electrical component, a piece of junk or component when gutted.
you can try to sneak spear them, but it should be really hard with a spear throw.