Cohort Analysis of Size Frequency Distribution with Computer Programs Based on a Graphic Method and Simplex's Method

Abstract

In ecological studies of aquatic organisms which can not be aged directly, the analysis of size frequency distribution of the population is a popular method to reveal the genera-tion structure and some population parameters such as growth rate and survivorship in the population. However, this analysis is time consuming, and requires considerable effort, from preparation of data to calculation of size frequency distribution of each cohort. In the last decade, we have created a software package named PROGEAN (PROgram for GEneration ANalysis) which provides a quick processing environment in the analysis of size frequency distribution with a personal computer. The previous version of PROGEAN (Ver. 3.0, Japanese version for NEC PC9801 series) adopted a graphic method modified from HARDING' S method and required inputting size data of specimen, producing the re-sults of the analysis on the monitor of computer. In this version, PROGEAN Ver. 4. 0, the programs were totally updated with MicroSof t Quick Basic Ver. 4.5 and many functions were added. PROGEAN Ver. 4.0 is made up of 12 subprograms. A data file is created by inputting data from keyboard or graphic digitizer, or importing a text file from other sof twares. On the monitor, a chart of size frequency distribution is created and the results of cohort analysis are plotted on the chart. This chart can be printed with a XY-plotter. Cohort analysis in these programs includes two procedures, analysis of graphic method and optimization of the results produced by the graphic method. These two steps of cohort analysis provide more precise results and easier processing environment of data than the previous version. Two types of programs are available. One is PROGEAN 4. 0J for Japanese domestic personal computers, NEC 9801 series, and the other is PROGEAN 4. 0E for IBM PC/AT and its compatibles with CGA video adapter.