The total weight of the fish in a stock that are old enough to spawn. The annual recommended catch for a species or species group. The regional council sets the TAC from the range of the allowable biological catch. A measurement of the rate of removal of fish from a population by both fishing mortality and natural causes. Total mortality can be reported as either annual or instantaneous.
Annual mortality is the percentage of fish dying in one year.
Instantaneous mortality is that percentage of fish dying at any one time. The rate of total mortality may vary from species to species. The production from a fishery in terms of numbers or weight. A model that estimates yield in terms of weight, but more often as a percentage of the maximum sustainable yield, for various combinations of natural mortality, fishing mortality and time exposed to the fishery.