The Database on the Inland Fishery Resources of Africa (DIFRA) is a data bank, based on dBASE IV software, with information on morphometric characteristics, limnology and fisheries of more than 1 000 African inland waters. It has the Source Book for the Inland Fishery Resources of Africa (SIFRA) (Vandem Bosche and Bernacsek, 1990a, 1990b, 1991) as its principle source of information.
The Source Book for the Inland Fishery Resources of Africa is a compendium, country-by-country, water body-by-water body, of physical characteristics, limnology and fisheries. It also provides, when available, estimates of the fishery potentials of those water bodies. The information is summarized nationally covering fifty-three countries.
The Source Book - an activity of FAO Inland Water Resources and Aquaculture Service - evolved from two CIFA publications (Welcomme, 1972, Welcomme, 1979). Furthermore, a large number of other more recent sources were used.
The Source Book is published in three volumes, each one corresponding to one of the following regions:
| - Region 1: | East and Southern Africa, including the islands Madagascar, Comores, Seychelles, Mauritius and Reunion |
| - Region 2: | Western Africa from Senegal to Congo |
| - Region 3: | Northern Africa |
The present database will be periodically updated as a Regular Programme activity of the FAO Inland Water Resources and Aquaculture Service. In this way it will provide comprehensive, up-to-date information on Africa's inland fisheries and fishery potential and will be readily accessible to planners, policy makers and fishery workers.
The database will be useful to identify under- and overexploitation of water bodies by comparing potential yield estimates with actual catches. The same kinds of comparisons can be made for shared water bodies and selected regions or countries. The results can be used to identify where possibilities for fisheries and/or aquaculture development are greatest.
Complementary information on African fisheries and fisheries projects is available in a number of other FAO databases. The FAO Fishery Development Planning Service (FIPP) is currently developing a Fisheries Policy and Planning Data Bank (FIPPDAT) based on dBASE software in cooperation with the Fishery Information, Data and Statistics Service (FIDI) (FAO, in press). The databank will be a country-by-country compilation of data from national reports and statistics imported from FAO Fisheries Department's FISHDAB and other FAO and UN databases.
FAO published a socio-economic database on African Fisheries (Bonzon and Horemans, 1988) which gives a preliminary compilation of statistical information on basic socio-economic indicators for African fisheries in two modes (most recent data and time series (1970–1986) and according to different levels of aggregation (country, geographical zone, and economic community grouping).
For information on fisheries and aquaculture development projects, FIPIS (Fisheries Project Information System) can be referred to. This database of FAO's Fishery Policy and Planning Division, also based on dBASE software, gives information on almost 3 000 fisheries and aquaculture projects all over the world.
The countries given in the database, are listed below in alphabetical order together with the corresponding volume of SIFRA (1,2,3) (Table 1).
Time series (1970–1987) of fish production and per caput supply are given per country. Population numbers are expressed in thousands of inhabitants. The main sources are UN population data (UN Population Division) and World Bank socioeconomic indicators as available through the FAO AGROSTAT database (Information System of Agricultural Statistics). Fish production figures exclude exports and are taken from FAO Fisheries Department's FISHDAB. Aquaculture production and supply are included in inland production when not specified. Nominal consumer supply is calculated by dividing production by the population of the country resulting in a per caput supply in kg/person. Additional information on data is given in the “Memo Field” of the time series tables (see Section 3.2).
Table1. African countries covered by DIFRA (Source Book volume in brackets)
Algeria (3)
Angola (1)
Benin (2)
Botswana (1)
Burkina Faso (3)
Burundi (1)
Cameroon (2)
Cape Verde (2)
Central African Rep. (1)
Chad (3)
Comoros (1)
Congo (1)
Côte d'Ivoire (2)
Djibouti (3)
Egypt (3)
Equatorial Guinea (2)
Ethiopia (3)
Gabon (2)
Gambia (2)
Ghana (2)
Guinea (2)
Guinea Bissau (2)
Kenya (1)
Lesotho (1)
Liberia (2)
Libya (3)
Madagascar (1)
Malawi (1)
Mali (3)
Mauritania (3)
Mauritius (1)
Morocco (3)
Mozambique (1)
Namibia (1)
Niger (3)
Nigeria (2)
Reunion (1)
Rwanda (1)
Sao Tome and Principe (2)
Senegal (2)
Seychelles (1)
Sierra Leone (2)
Somalia (3)
Sudan (3)
Swaziland (1)
Tanzania (1)
Togo (2)
Tunisia (3)
Uganda (1)
West Sahara (3)
Zaire (1)
Zambia (1)
Zimbabwe (1)
Selected data of more than 1 000 African inland waters compiled in SIFRA are stored in the database. The water bodies are divided into five types: lakes, rivers and floodplains, reservoirs, swamps, and coastal lagoons.
International waters are identified in the countries where they are situated. All available morphometric and limnological information on African waters of direct importance for potential yield prediction and fisheries has been stored in the database. Fishery statistics (catch, number of fishermen and number of boats) are given when available, starting from 1950 until 1987. Additional information has been stored in “Memo Fields” in the different database tables (see Section 3.2).
Potential yield estimates from analytical studies on fish stocks (acoustic surveys, trawl surveys) and/or fisheries (catch-effort analyses) have been given when available. Most African water bodies and fisheries, however, have not been studied in this way. In the absence of these data, potential yield estimates have been made using models based on morphometric and chemical data of the water bodies. The development of these models is the subject of another report (R.C.M. Crul, 1992, CIFA Occasional Paper No.16, “Models for estimating potential fish yields of African Inland Waters”). Potential fish production per country has been calculated by summation of the potential yield estimates of the different water bodies.
dBASE IV of Ashton Tate has been selected for this database. First, it is a wellproven, readily available, commercial database programme for IBM PC and 100% compatible PCs. Secondly, dBASE IV is more powerful than earlier dBASE versions and most other programmes and has full upward compatibility with data sets of dBASE III+. dBASE IV needs 640 Kb RAM memory for operation which is now a standard memory for XT and AT class PCs and portable computers using the MS DOS operating system. A hard disk with 7.5 Mb free disk space (3.5 Mb for the programme, 2 Mb for the DIFRA tables and an additional 2 Mb for operation) is necessary.
dBASE IV has a Control Center, interface with facilities such as “Forms” “Queries”, “Reports”, “Labels” and “Applications”. The Control Center can work with different catalogues and with different sets of files. The programme can use SQL (Structural Query Language) to carry out more complex queries and views.
Query by Example (QBE) and Structural Query Language (SQL) are two interesting facilities of dBASE IV which can be used to create a view. A view is in fact a virtual database table created by the user which can be stored on disks in a separate file. As SQL requires experience in programming and SQL commands, and QBE has a user-friendly visual presentation using a “Query Design Form”, QBE has been chosen as a standard for DIFRA with the possibility for SQL users to switch to SQL.
In the “Query Design Form” database tables can be linked and retrieved in every form. Records can be selected by adding conditions, for example, select all lakes with an area > 100 km2 and a conductivity < 250 μS/cm and catches > 2 000 tonnes.
