As usual you're missing the whole point with your flawed logic.
As demand rises, prices rise, creating incentive to harvest more of these feed fish in an unregulated jurisdiction. There is absolutely no chance that commercial operations will curtail their fishing for these feed fish. Even if regulations were put in place there would be no way of monitoring and enforcing them.
It's obvious that the salmon feedlots have no intention of cutting back on production. This pressure on the fish stocks will lead to a collapse of the stocks. Saying it's not the feedlots responsibility is consistent with what we have come to expect from the feedlots. It's also consistent with their disdain for the wild salmon, the ocean environment and the folks that are trying to preserve it.
As usual, your ignorance of the subject leads you to faulty understanding and consequent erroneous conclusions that you feel the need to present in your usual fashion by suggesting that it is someone else using flawed logic.
Fish meal is a cocktail of various proteins, minerals and trace elements in a fairly specific proportion. These constituent elements are required in various amounts and proportions in the diet of all animals, birds and fish. These are also available in various assortments at various proportions in a variety of other compounds and substances, both synthetic and natural, at various price points. Each of these sources can also contain compounds that have negative effects on the animals they are fed to.
Formulating a feed involves analyzing the dietary requirements of the animal to be fed and then selecting among a variety of sources for the constituent elements required based on cost, availability, assortment and proportion of elements supplied and absence of non-beneficial elements. There are multiple ways a diet can be formulated; cost is the final determinant criteria. If any particular source compound becomes more expensive, the diet is reformulated using other source compounds that also contain those elements which have become relatively less expensive as a consequence of the increase in cost of the one currently used.
Fish meal is almost ideal for the formulation of the diets for aquatic animals because it generally contains the required constituent elements in appropriate proportion for those animals without containing non-beneficial elements. Pigs and chickens have requirements for many of the elements but in different proportions so fish meal is considerably less ideal for their requirements. Consequently, it has higher value to formulators of fish feed than it would to formulators of pig or chicken feed and the price fish feed manufacturers are willing to pay is higher than that the formulators of pig and chicken feed are willing to pay. That is why the supply used in fish feed has increased and that used for pig and chicken feed has decreased. Those feed manufacturers have switched to other, lower cost sources for the constituent elements they require.
If the demand for fish meal for salmon diets decreases, the price of fish meal will also decrease and this causes a change in the economics of formulating other feeds and those other feeds will start to use more fish meal. Non-salmon aquatic demand and non-aquatic demand will absorb any newly available, lower cost supply resulting from a decease in use in salmon diets until such point as their increased demand causes sufficiently increased price that other alternatives become more economic. At that point, demand will level off again. In the interim, harvests of fish for fish meal will increase to stabilize fishing income and it is unlikely it will decrease again once the point of demand stability is reached.
In simplest terms, in spite of your flawed understanding, eliminating salmon farming demand for fish meal will decrease the price of meal resulting in increased demand by other feed sectors and that will stimulate an increase in supply. The only way to regulate supply of fish meal is to regulate the fishing for the fish that fish meal is made from just as fishing for salmon, halibut and a multitude of other species has been regulated.