How would you learn to survive if you moved from a generations-long residence on the Pacific coast to the volcanic interior highlands?

Our archaeological information from Central America suggests that many of the earliest residents lived along the Pacific and Gulf coastlines. These are areas where marine resources were plentiful and easily harvested. But early in the Preclassic period some of these coastal residents began to move along the river valleys into the unexploited highlands. The highlands of Guatemala are volcanic in origin. This means they have very rich soils excellent for agriculture, but they are also subject to earthquakes and eruptions, and the hillsides are easily eroded during slash-and-burn farming. Worst of all, there are no marine resources to exploit. Dr. Eugenia Robinson's excavations at the site of Urias close to Antigua have turned up enormous quantities of well preserved animal bone that I am using to search for information on how these coastal immigrants adapted to their new environment. What animals did they hunt? If they couldn't eat sea-creatures, did they replace them with riverine ones? And were there some species that were familiar enough that they knew how to find them regardless of whether they lived on the coast or the hillside?