>One prominent study said 55 percent, its critics say 4 percent, and they both used the same data.

TL;DR - The first study (55% fished) divided the ocean in 160,000 squares (each 3,100 square kilometers) with 55% containing fishing activity in 2016.

The second study divided the ocean into much smaller squares (123 square kilometers)and found only 4% had fishing activity in 2016.