Abstract:
Shrimp aquaculture is highly profitable industry compared to traditional fisheries, animal
husbandry and agricultural activities in Sri Lanka. Inter-tidal zones including ecologically
sensitive areas (mangroves and salt marshes) and supra tidal zones developed for traditional
agriculture have been converted to shrimp farms in the North western province of Sri Lanka.
Socio- economic systems and biophysical systems are interdependent and there is a indivisible
interaction between these systems affecting each others.
Physical changes in water sources as a result of activities related to shrimp culture include
siltation, sedimentation and increase in concentration of total suspended solids levels. Toxic
metabolic end products and self pollution has created an environment unfavorable for both
culture shrimp and other commercially important fishery resources exploited by coastal
community
Changes in the land use pattern in adjoining land of coastal water bodies have in affect sevaral
adverse impacts on whole lagoon system in the North- Western province. This study was mainly
focused on reviewing the affects of the changes in lagoon system on the socio-economic
responses of the coastal community and their use of biophysical resources. Increases in the use of
ground water in the area has reduced salinity content in the lagoon and also has resulted in
lowering ground water level in the area. Changes the physical environment has resulted in a
change in fish composition, which lead to decrease of main income of the traditional fishing
community in the region. Some of the seasonal fishing activities have been abandoned. Most of
the ecological systems, such as mangroves, salt marshes and inter tidal ecosystems which were
fish breeding grounds, grazing lands for animal husbandry activities and protecting area for
tidal erosion have been destroyed.
Changes in the lagoon system and environment have caused changes in economic and social
activities of the native community. It was observed that some of the full- time fishermen in the
lagoon have converted to be part- time fishermen while some have totally abandoned fishing in
the lagoon. Presently, fishermen are involved in fishing with harmful non- selective methods and
they have increased the use of family labour instead of hiring crewrnember. It has resulted in
increase in number of fishermen in the lagoon. The fishermen who stopped fishing due to less
return from the lagoon have compelled to go as members of the off shore fishing crew, fishing in
the sea or working as a labourer in shrimp farm or they are involved in other non-fishery
activities in the area.
Several user- conflicts have been identified between shrimp farmers and communities engaged in
traditional economic activities in the area. During the late 1980's and 1990's frequent disease
outbreaks have reduced farms production to its lowest level. Contaminated larvae, intensive
culture practices, deterioration of water quality in main water sources, problems related acid
sulphide soil conditions have been identified as main contributing factors for disease out-breaks
which have led to reduction in employment opportunities in shrimp farming sector. The
frequency of vector bone diseases have increased in shrimp farming areas. The neglected
shrimp rearing ponds appears to provide major breeding places for mosquitoes during the rainy
seasons.
The prevailing problems cannot be totally solved by implementing the institutional regulation
since the communities living in the region are traditionally involved in their economic activities
which depend on the ecological systems. Alternative sources of income are one of the short -term
solutions to the problem, but this is not a permanent solution to improve the resource generation
in degraded lagoon system