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An extract from Two stock-assessment programs for a programmable pocket calculator, W.G. Doubleday, Fisheries Research Branch, Department of Fisheries and Environment, ICNAF Res.Doc. 77/VI/47, JUNE 1977

"Continuing advances in computing power of pocket electronic calculators now allow stock-assessment calculations usually performed by computers to be carried out virtually at an assessment meeting table. Programs for virtual population analysis and catch projections for the newly-released HP-67 calculator are presented here.
Virtual Population Analysis
The first program performs cohort or exact virtual population analysis on a year-class of up to 19 age-groups. Data are retained so that alternative values for natural and fishing mortalities can be examined without re-entering data. The exact solution follows the method of Doubleday, 1976. F is estimated to 0.001 or the predicted catch is within 0.001 of the observed catch, whichever occurs first.
Catch Protection
A standard catch projection for up to ten age-groups is performed. Either TAC or F may be set and the other calculated. Changing the units of population size makes corresponding changes on the units of output so that the desired number of significant digits can be retained."

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