It's called predation... Wal*Mart and its ilk run down the weak of the herd -- towns with struggling economies, small businesses -- rip their guts out, feast, and leave the carcass for the crows and hyaenas, moving on to the next kill).  It's a mode of interaction that's frankly maladaptive when exercised within the kin group...  families that eat their own family members don't survive as well to pass on their genes as families who cooperate.  I think we can see by the current parlous condition of the US economy that the predation model seriously weakens the state that permits it to be practised freely.

BTW, I should note (on the salmon theme) that the fodder source for many of these fish farms is ocean-caught fish, i.e. the product of the indiscriminate slaughter conducted by factory trawlers.  Farmed salmon does not necessarily alleviate the pressure on wild species;  the wild species, regardless of size, age, or rarity, are "harvested" (stripmined or clearcut would be a more accurate term) to make food for the factory fish.

Also the salmon farming industry is one juicy target for the gene vandals;  the "invention" of mutant faster-growing salmon was originally for factory farming purposes (to accelerate the life cycle of the fish and reduce the time from spawn to marketable meat).  Of course these mutant fish are not going to stay neatly confined in the coastal farms, and in the wild they will compete successfully and outbreed indigenous salmon varieties, or other native fish species.

It's worth remembering that the fish species we like to eat are almost all top predators in their marine or river niches.  Eating them as a staple food is like eating lion, or bear, or wolverine as a staple food.  They are relatively rare and play a key role in functioning food chains.  Their elimination or reduction to pathetic levels has enormous destabilising impact because of their predator role...

At the same time, human activity is chopping and chipping away at the very bottom of the ocean food chain, (1) by global warming which threatens plankton populations worldwide in warming waters, (2) by nitrate and pollutant runoff which creates enormous dead zones off many industrialised coasts, and (2b) by antibiotic and estrogen-mimicking compounds which interfere with disease resistance and with reproduction of marine species (3) by incredibly destructive bottom-dragging nets which literally scrape all life off the seabed in a wide swathe, destroying hundreds or thousands of species to get at a few valuable "catch" species (a kind of "collective punishment" applied to hunting, like fishing with dynamite).

It is sheer vandalism, and all so that proletarians in the wealthy countries can emulate the diet of aristocrats of a generation or two generation ago...

The difference between theory and practise in practise ...