ABSTRACT
Mortality rates are a measure of the rate at which fish disappear from a population. A primary goal for management of exploited populations is to regulate harvest such that the total mortality rate that which allows the population to persist. Thus, estimates of mortality rates are critical information for fish managers. Population models may be expressed in a continuous form such that the rate of change parameter is an instantaneous rate. The typical exponential decline in numbers of fish at each age is linear when the natural logarithm of catch is plotted against age. Estimates of apparent survival from one time period to the next can be estimated for open populations using capture-recapture data. The instantaneous rate of natural mortality is highly correlated with various life history or abiotic factors. A number of researchers have exploited this relationship to develop simple models for predicting M from these other factors.
