Final answer:
Mike Fink, Jedediah Smith, and other mountain men and fur traders helped open up the Pacific Northwest primarily by exploring and establishing trade routes, rather than by creating permanent settlements or negotiating treaties with Native American tribes.
Step-by-step explanation:
Mountain men and fur traders like Mike Fink and Jedediah Smith played a crucial role in opening up the Pacific Northwest to settlement. Their contribution was not in establishing permanent settlements nor in negotiating treaties with Native American tribes. Instead, their main role was in exploring and establishing trade routes, which effectively made them pathfinders of the West. This exploration and subsequent mapping provided valuable knowledge of the region's geography and laid the groundwork for future settlers to follow. Among their activities, one can find their establishment of various trading posts and their interactions with Native American tribes, which set the stage for increased migration and development in the territory.