Z

total mortality rate (the number of fish which die during a year or season, divided by the initial number. Also called actual mortality rate, coefficient of mortality. Instantaneous rate of mortality (the natural logarithm (with sign changed) of the survival rate. The ratio of number of deaths per unit of time to population abundance during that time, if all deceased fish were to be immediately replaced so that population does not change (Ricker, 1975). Also called coefficient of decrease)