If the ends justify the means, then lets promote the use of sweatshops. After all, the world is full of billions of poor people, so why not use their cheap labor to provide cheap goods for the rest of us? I don't see why you take such a hard-line attitude towards protecting animals, especially when they are harmed as a result of human activity -- activity which we have the ability to change if only we decide to do so.
On your second point, the attitude that the oceans are filled with billions of fish (not "foodfish") is the same attitude which is leading to the severe decline of many fish species, such as cod. They are disappearing from the oceans, much like the supposedly-infinite herds of buffalo nearly disappeared until people stopped killing them.
Lastly, we need to eat less fish and more legumes and grains. That is how you feed a starving world.
None.
