In this case, fishing is very much comparable to hunting. Only we use much cruder and more destructive hunting methods underwater because we are not at home in the ecosystem.
As predators, tuna are involved in the regulation of numerous other species, migrate almost all over the world throughout the year and dive for miles depending on the time of day. Fishing them is like normalizing the hunting of tigers. Maybe even worse. After we have already wiped out some tiger species. And all for a cheap pizza topping.