Historical policy goals for fish management in northern continental Patagonia Argentina: A structuring force of actual fish assemblages?

Early in the 20th century, the Fish fauna of Patagonia consisted of 20 native fish species. In 1904, exotic species, mostly salmonids from North America and Europe, were introduced, giving rise to an extensive sport Fishery. Scientific literature, stocking and catch logbooks, and registries of organizations in charge of enforcing management practices were searched in relation to effects of probable policy goals upon actual Fish assemblage structure of two major river basins of northern Patagonia. Policy goal history in this region can be divided into three periods. Between 1904 and 1910, goals were focused on increasing diversity and sport fishery opportunities through salmonid introductions. From 19 10 to 1970, goals shifted towards development of both commercial and sport Fisheries, increasing diversity by introducing and restocking salmonids and native fish species and preserving both through fishing regulations. In these two periods, policies were centralized under the federal government. From 1970 on, policy has been characterized by decentralization in relation to provincial and national park jurisdictions. The former fosters the development of sport fisheries, while the latter focuses on the protection of native Fish species and opposes new introductions. However, Patagonia's isolated environments, lack of road infrastructure, particular management circumstances, biological capacities of released species, and great dispersion capacity of salmonids were fundamental factors that shaped the artificial and natural dispersion in both the Negro and Manso River drainages.