Two fisheries stock assessment software packages were produced under FMSP project R4517: CEDA (Catch and Effort Data Analysis) and LFDA (Length Frequency Data Analysis). CEDA analyses catch and effort data to provide estimates of current and unexploited stock biomass, other population dynamics parameters, and can be used to make stock projections under different catch scenarios. LFDA analyses length-frequency data to provide estimates of von Bertalanffy growth parameters and mortality.
More than 50 copies of these packages were distributed to scientists in developing countries during the first year after their release. A number of comments on the use of the packages, and requests for additional features had been received, clearly identifying a need for updating and revising the software.
The project revised the existing software package through evaluating their applicability to the assessment of tropical commercial fish stocks, and their applicability for use by tropical fisheries scientists. Three detailed case studies were undertaken for the evaluation; in Thailand, Turks and Caicos (Caribbean) and Zimbabwe. Additional feedback on the use of the packages by others also contributed to the revision of the software.
Revised versions of CEDA and LFDA, with accompanying new user manuals, were successfully produced, and form the principal outputs of the project. The new versions included extensive revisions of old features, and a number of very powerful new options. For CEDA, the ability of the package to fit a model to certain types of data sets was improved by running minimisation routines from three different starting points, and then selecting the best parameter estimates. For LFDA, the main improvement was the inclusion of a seasonal growth model. Improvements to the data entry and editing facilities, and the user interface were made for both packages and extensive context-specific on-line help files were incorporated throughout.
The new packages were reviewed by experienced stock assessment specialists, and their comments were incorporated into the final versions.
The results of the data analyses performed using the software as part of the field testing provided additional outputs from the project.
Note: CEDA and LFDA were subsequently rewritten for Windows. The latest versions of these software packages are available for download within the publications tab. The Final Technical Report for the revised software is also available there.