Why would the government protect fishing industry by preventing other countries from fishing inside the 200 nautical mile limit?

the reason why the have a 200 mile zone (EEZ) is so the country can have control of the fishing industry around that country. The first country Canada to create the EEZ as it had a mortitorum or ban on Cod fishing in the Grand banks. They could only control fishermen in they own country, so they decide to make a zone where only they could fish. the grand banks extend outside the 200 hundred mile limit. cod being fish tend to swim around, so other countries (yanks europeans ect. ) could just sit outside the boundry and pick off the cod as they moved around the bank. hence defeating any conservation measure the dfo put in place for Canadian fishermen. so the only real losers before they took this action were the canucks.