The First World War interrupted the growth of the industry with many fishermen enlisting the Royal Naval Reserve. They returned to a declining industry which was further interrupted by the Second World War in 1939. After 1945 much of the effort became concentrated on whitefish with an additional sector exploiting shellfish. Technical developments have concentrated fishing in the hands of fewer fishermen operating more efficient vessels and, although the annual value of catches continued to rise, the number of people working in the industry fell.