Previous research into Australian convict transportation has concluded that a significant downturn in mortality rates occurred with the appointment of naval surgeons as superintendents in 1815. Statistical analysis of convict ships sent to New South Wales between 1787 and 1849 shows a more significant downturn occurred in 1800, following the introduction of closer supervision of ships' surgeons. The contracting system established by the Navy Board in 1786 for the transportation of convicts to New South Wales could be made to work as long as government maintained an effective system of inspection and supervision.
Sturgess, G., Rahman, S. and Argyrous, G. (2017). Convict Transportation to New South Wales, 1787–1849: Mortality Rates Reconsidered. Australian Economic History Review, early online, doi 10.1111/aehr.12137.