8. Size management
AS MENTIONED IN SEVERAL SECTIONS of this manual, freshwater prawns do not grow at an even rate (Annex 8, Figure 1). This makes the management of size an essential com ponent of the efficient husbandry that is needed to ensure their successful farming.
A con siderable volume of knowledge about the different (male) morphotypes which play a part in the phenomenon of uneven growth has been gained since the previous FAO manual on freshwater prawn farming was written. The topic has been reviewed in depth by Karplus, Malecha and Sagi (2000), from which the material in this annex has been derived. The main purpose of Sections 1-3 in this annex is to provide an introduction to the scientific background; it is necessary to study this to understand the phenomenon of size distribu tion and management. Practical advice on management contained in the main text of the manual has taken these factors into account. Section 4 of this annex provides a check-list of the various techniques which it is essential that farmers apply to get the maximum out put of marketable prawns.
| 1. Major male morphological characteristics |
| 2. Behaviour |
| 3. Importance of population structure in freshwater prawn farming |
| 4. Managing grow-out in the light of heterogeneous individual growth (HIG) |