By the 1860s a few Islanders were entering into partnership with larger American fishing companies. Even so, the mackerel fishery remained a mainly American concern. In the mid-1880s the mackerel stocks collapsed - due to over-fishing - and the Gloucester fleet disappeared forever from Prince Edward Island's shores. It probably would have been very quiet out there, if the lobster fishery hadn't already begun to take its place.The fishery was an expensive business to get into. Catching and processing cod and mackerel - the main commercial species at the time - required a major investment in boats, gear, wharves and warehouses. Most Islanders with this sort of capital thought shipbuilding a safer investment and left large-scale fishing to the Americans.