Do chimpanzees and bonobos gather a significant portion of their food from water resources? Archeological records of ancient homonids show remnants of mollusks

Do chimpanzees and bonobos gather a significant portion of their food from water resources? Archeological records of ancient homonids show remnants of mollusks and fish going back long before this report of "evidence of swimming". It seems logical that species would proficient in moving about the environments where they regularly gathered food.