Norwegian spring-spawning herring and Northeast Arctic cod are two of the largest and commercially most important fish stocks in the North Atlantic. Both these stocks have their spawning fields at the Norwegian coast and they have been the major target species for Norwegian fisheries for a millennium. They are also among the few fish stocks in the world which have been systematically investigated and monitored for more than a century. The scientific results arrived at early in the century for these two stocks, formed the basis for much of the development in international fisheries science later on. This book describes how fisheries, fisheries science and management for Norwegian spring-spawning herring and Northeast Arctic cod developed during the 20th century. Both populations had serious declines in stock size and yield due to overfishing. The herring stock was in a state of collapse for about 20 years. Management measures introduced during the two-three last decades made both stocks recover in the 1990s.