Abstract:
Penaeid shrimps consist of approximately 110 species of which about 10 species
are important for commercial culture. In Sri Lanka, Penaeus monodon species are
found naturally in the coastal areas around the country and, matured wild caught
shrimps are used as the brood stock in shrimp aquaculture industry.
Morphometric differences among stocks of a species are recognized as important
tool in evaluating the population structure. This study investigated the variation
of morphological characters among P. monodon stocks collected from two
different geographical areas of Sri Lanka; east coast (Batticaloa, n=58) and west
coast (Chilaw, n=52). Truss network analysis of twelve measurements were
standardized with equation LTs(i) = log10 LT(i)[log10 TLm / log10 TL(i)]b.
Principal component analysis (PCA) was performed to test morphological
variations within stocks. Wilks’ Lambda test revealed that there are significant
difference in all morphometric variables between east and west coasts (Wilk’s λ=
0.11233, F (12, 95) = 62.562 and p ˂ 0.05). Two principal components derived
from PCA analysis accounted a total of 65% variance in truss measurement data.
The plot against first (PC1) and second principal components (PC2) scores
showed heterogeneous stock structure in east and west coast of Sri Lanka.
Present finding is important for the brood stock development programs and
uplift knowledge of phenotype of the P. monodon species. Studies on population
genetics studies are recommended to confirm the results of the present study.
