[myshpa]

"There are large areas in the middle of the major oceanic basins called the subtropical gyres. These could be considered the deserts of the ocean in that the biomass (total mass of all organisms) density and biodiversity are low. This is because the ocean circulation doesn't replenish the nutrients available in these areas for algae to live off, which are the base of the food-chain.

In general, you tend to find much more biomass and biodiversity closer to the coasts. But you can get hotspots of productivity in other places such as upwelling regions and also near seamounts (shameless plug of my paper on this)."

"People assume, well oceans are massive so fish stocks are massive as well. But if you went hunting for game as a protein source you wouldn't assume it lives at the top of every mountain and bottom of every valley. You know it has a range that confines its distribution and therefore its abundance. You dont go hunting across the vast, empty desert.

Commercial fisheries know this and are squeezing the last bits they can out of the pelagic fish we all expect on the dinner table (tuna, mahi, etc), but as you aptly point out, the majority of fisheries biomass is near the coast. Fish we eat do not come from habitat that covers 70% of the planet, its much closer to < 10 %."

https://www.reddit.com/r/askscience/comments/imu81a/if_you_p...

https://www.sciencealert.com/there-s-a-desert-in-the-middle-...