F

1) the fishing mortality rate in a particular stock. It is roughly the proportion of the fishable stock that is caught in a year and is derived mathematically from relations between the number of fish alive in a stock and the number of fish caught. When F is 0, no fish are being caught from a given stock. When F is 0.2 then 18% of the fish are being caught and this is almost the same as the exploitation rate and the rate best for most groundfish fisheries. At an F of 0.5, 39% of the fish are being caught and at 1.0 63%. F can exceed 1.0 though this would not be good fishery policy. See also F_max and F_MSY below

2) Fahrenheit