Another view on the oceans:

It really doesn't matter how deep you go fishing. The productivity of the oceans is dependent on the amount of solar energy that falls on the surface. All living things are, ultimately, solar powered via photosynthesis.

You've entirely neglected the ocean thermal vent ecologies powered by the endogenous heat energy of the Earth.

We could start eating these vent worms:

Doesn't that look tasty?

Some people even think that those thermal biosystems are the origin of life on earth and, gosh, they could amount to a tiny fraction of the bio-productivity of the ocean even today.

I am of course seriously joking.