I like the creative construction of your game. With limited time, abstracting the fish to shadows helps save time and clearly marks the "Underneath Us" theme of the jam. I see that the basis of your gameplay loop is done, and there's potential for improvement.
Some feedback:
- It would be great if the boat had some sort of dash ability to temporarily go faster. You can possibly have a separate bar for a dash timer or you could make it take some of your health if you go faster.
- Sound effects would be great
- Score would be great