This legislation includes a number of interesting provisions. The most salient, in my view, is that it prohibits the transport, outside the Province, of unprocessed fish. Indeed, Article 37 bars the holders of a Provincial fishing license from shipping raw material to operators outside the Province, unless provided for in inter-Provincial agreements.
One of the main objectives of such provisions is make sure that there is a processing industry in the coastal areas adjacent to the fishing grounds. Because fishermen are obliged to deliver the raw material in these areas processing companies might benefit from more abundant fish and therefore pay lower prices for their raw material.
Is this a subsidy?
This brings to my mind two cases, one in the context of the GATT, the other at the WTO, involving Canada and the US in relation to restrictions on exports. In the first one, the US complained because Canada introduced export prohibitions of unprocessed herring, herring roe, and pink and sockeye salmon. The second case concerned a complaint by Canada about certain US measures that treat a restraint on exports of a product as a subsidy to other products made using or incorporating the restricted product if the domestic price of the restricted product is affected by the restraint.
Here in the link to the webpage of the official website of the Chubut Province displaying the contents of the legislation (in Spanish):