studies on improved practices of prawn farming for higher ...

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George, 1974 and Gopalan et al., 1980) regarding the mode of operation
and yield obtained through the traditional system. The details of
yield and economics of prawn culture from fields of Vypeen island have
been worked out (George, 1974; Purushan, 1986; 1987). Studies by
Purushan and Rajendran (1984) indicated that shrimp production from
traditional fields is gradually dwindling year after year, the present
yield being 300-400 kg/ha/year in addition to 200-300 kg of fish. But
Silas and Rao (1987) estimated the average annual yield of fishes and
prawns from traditional system as 1070 to 1570 kg/ha/season. While
shrimps contributed only 33.3%, the rest was contributed by fishes such
as mullets, pearl spot, tilapia, cat fishes and crabs ficyllagserrata.
On an evaluation of the efficiency of management and
productivity of traditional brackishwater farming practices of central
Kerala, the author noted 5 chief defects in the systes.
The system does not involve fertilization of the field,
additional stocking, supplementary' feeding of the impounded stock,
control over competition and predation and provision for sufficient
time for growth. These defects could be rectified at little extra care
on the part of the shrimp farmers (Purushan,l987). Hence, in order to
transform the traditional practice to an improved system, emphasis
given cni the following aspects during the present series of
investigations become more relevant in the Kerala situations.
a) eradication of udesirable organisms
b) preparation of the field as a habitat before stocking
c) selective stocking with fast growing species that command
good price
d) supplementary feeding
e) allow the species to attain marketable size within short
time.