You need to carry sardines.
Believe it or not, there is even a sardine quote from the classical mountaineering literature of the 1930s.
There is something peculiarly unappetizing about a frozen sardine in gelatinous oil at 25,700 feetFrank Smythe,
Camp Six, in
Frank Smythe,
The Six Alpine/Himalayan Climbing Books, p 602