They "mainly" subsisted on their onboard rations of food and water, to which they added fish whenever they could, but which wasn't as often as they liked.

Crew members would fish whenever they had free time and the weather permitted, but whether they would actually catch something was very uncertain, and certainly not something they could count on. So the main food had to be provided from ship supplies onboard, with the caught fresh fish serving only as a bonus if it was even applicable.

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