He was forced to do this, according to a memoir by his grandson, Bernhard Caesar Einstein, after his doctor tried to make him give up smoking.
The recollections by Bernhard Einstein, 75, were published in a Belgian newspaper, Le Soir. He describes how his grandfather disapproved of fishing as a sport and believed fish should only be caught for eating. "Grandfather would only allow me to go fishing if I ate all the fish I caught, so I caught one fish early in the morning and ate it for breakfast."
He describes a sailing trip with the celebrated physicist: "He [Einstein] usually said very little to me during those outings but on one particular afternoon, one on which there was practically no wind, he became talkative. He liked the calm and claimed that calm was the highest challenge to the sailor. We went no further than about a kilometre in the three hours we were out."