Many of the existing sharing agreements seem to be quite resilient to these variations, even if no formal allowance is made for this. The sharing of the North Sea stocks between Norway and the EU is based on an investigation carried out in the early 1980s and has withstood the test of time, with the exception of the North Sea herring already discussed. But both the North Sea herring example and the north Pacific salmon runs indicate that if changes in fish migrations are too dramatic and long lasting, agreements on stock sharing will indeed come under pressure. The example in the previous section about a stock migrating out of Country A’s area into Country B’s area is perhaps particularly pertinent to stocks straddling into the high seas, with the latter replacing Country B’s EEZ in this context.