Complex sentence: During the 1960s and 1970s, oil exploration companies determined that the seafloor beneath Georges Bank possesses untold petroleum reserves, however both Canada and the United States agreed to a moratorium on exploration and production activities in lieu of conservation of its waters for the fisheries.
Split into simpler sentences: During the 1960s and 1970s, oil exploration companies determined that the seafloor beneath Georges Bank possesses untold petroleum reserves. However, both Canada and the United States agreed to a moratorium on exploration and production activities in lieu of conservation of its waters for the fisheries.