Serious production losses have occurred in shrimp producing countries
around the world, principally due to poor rearing environments and pat
hogenic disease. In response to this, shrimp farmers are changing thei
r culture methods. To understand the source and sink of nutrients whic
h affect pondwater quality and effluent impact, the nitrogen, phosphor
us and solids budget have been constructed for water exchange systems.
These budgets reveal the contribution of the pond bottom soil to the
accumulation of sediment and phosphorus and its potential contribution
of nitrogen to the pond system. A survey of shrimp farm water quality
and management practices in southern Thailand has also been completed
. This reveals a high proportion of farms using low water exchange met
hods of shrimp culture but without the ability to maintain suitable wa
ter quality in the production ponds. Shrimp production in these system
s is variable due to high incidences of disease and slow growth rates.
The pond processes that might cause this are suggested and potential
methods for their amelioration are discussed. Alternative culture syst
ems such as lined ponds, low salinity rearing and recirculation farms
are described in relation to their potential for remediating problems
within the shrimp culture industry. (C) 1998 Elsevier Science B.V. All
rights reserved.