Egypt's aquaculture production (705,490 tonnes in 2009) is by far the largest of any African country and places it 11th in terms of global aquaculture production. The aquaculture sector in Egypt is now a mature one having developed over a period of more than 30 years, but the financial performance of the sector is not well understood or documented, even though value-chain analysis provides a methodological tool to do so.
Details are given of techniques to be used in the handling of large amounts of data in the field of aquaculture. Two examples are given where different types of multivariate data analyses are performed on the compiled datasets to identify and quantify the effects of key variables governing growth and production of fish in manured pond systems cultivating tilapia and carp.
An equation is given for the selection of interval sizes for use in length frequency analysis of fish classes.
A method for estimating the instantaneous mortality rate (Z) is presented which was developed from a truncated equation for average length. The model has zero bias at equilibrium, but has no explicit solution for Z so that its solution requires a numerical method.
Details are given of the current database system used by the Collaborative Research Support Programme in PondDynamics/Aquaculture and Its Management. Suggestions are made regarding the design of a database.
In many countries, resource conflict is a leading risk to livelihoods. For some communities, it is a matter of survival. Yet, many development interventions aiming to address these challenges fail or fall far short of their potential. Common reasons include conflicting agendas, power and politics; poor local commitment and leadership; lack of coordination; plus high costs and low sustainability, as programs often unravel when development finance ends.
The article features two most commonly techniques for gene transfer in fish, microinjection and electroporation.
A method is presented through which the total mortality undergone by several fish stocks of the same species can be compared when growth parameters are poorly known or unknown. Whereas the estimate of Z obtained via the length-converted catch curve is highly sensitive to the input parameters K and L sub( infinity ), the ratio of Z estimates obtained for different stocks with the same combination of parameters is almost independent of these inputs, at least when the fit of the linear regression is good.
This selection of methods is based on lecture notes used at a FAO/DANIDA training course held in Mombasa, Kenya, in May-June 1980. The methods presented are: regression and correlation, estimation of growth parameters from length-frequency data, estimation of mortalities (total, natural, fishing mortality) and analysis of catch and effort data.
The use of length-structured methods for the assessment of fish stocks is reviewed in relation to the present status of tropical fisheries science. It is concluded that these methods, which emerged largely as a result of the development of sophisticated, yet relatively cheap, programmable calculators and microcomputers, will enable significant advances to be made in assessment of tropical stocks.