The Cagayan River is the longest river that cuts across different municipalities of Cagayan Valley, in the Northern Philippines. Lal-lo is one of its municipalities and it is known for its huge and extensive shell midden deposits composed of bivalve freshwater shells locally known as kabibe (Batissa sp.). These middens, or literally “trash,” are found along the riverbank, inland, and in limestone hilly formation, and are of prehistoric significance. Results of the ten-year continuous archaeological undertakings conducted in the areas of Gattaran, Lal-lo, and Camalaniugan showed that prehistoric shell-gathering people intensively utilized riverine resources from the Cagayan River, but did not strictly subsist on freshwater shells, especially kabibe. Bones recovered from the shell middens showed that they also relied on animals for their protein, indicating hunting and gathering subsistence strategies had been applied through time. Reliance on shellfish and wild animals, and eventually domesticated ones, were both consumed in a given time.