Overfishing—really easy to do with megaships equipped with sonar for fast fish finding—and the eventual result is no fish. When smaller boats were still in use, fisheries were sustainable, more or less. But in the past forty years, hyper-efficient hi-tech practices have put paid to a third of the productive ocean. … Now you've got bigger and bigger boats chasing smaller and fewer fish.

The point [is] largely scientific in character …[concerning] the methods which can be invented or adopted or discovered to enable the Earth to control the Air, to enable defence from the ground to exercise control—indeed dominance—upon aeroplanes high above its surface. … science is always able to provide something. We were told that it was impossible to grapple with submarines, but methods were found … Many things were adopted in war which we were told were technically impossible, but patience, perseverance, and above all the spur of necessity under war conditions, made men’s brains act with greater vigour, and science responded to the demands.
[Remarks made in the House of Commons on 7 June 1935. His speculation was later proved correct with the subsequent development of radar during World War II, which was vital in the air defence of Britain.]