| الملخص: | The giant Malaysian prawn, (Macrobrachium rosenbergii de Man, 1879, 2n=59), is an
important species for aquaculture in the tropics and subtropics. Currently, it has been
introduced into more than forty countries for this purpose. In the past half a century an
accumulation of a reasonable amount of literature that definitely aided in the success of
farming of this species was achieved. But after the decades extending from 1960s to this
date unit per area production is approaching a plateau; this is attributed to the
exhaustion of management improvement opportunities that typically contribute to crop
increases only during the first few decades that follow the start of farming an
undomesticated species. As a result, its aquaculture in Malaysia and other countries in
Southeast Asia faced challenges that lead to decline in production. This research was
conducted in order to dig reasons and find solutions for these challenges. So,
investigations were conducted through genetic and management studies. Pond
management investigations were conducted through an in-depth interviewing and
visiting of GMP farmers at their farms in Negeri Sembilan States. Results of this portion
of the study showed that many farmers are facing problems in obtaining seeds. In
addition, feed cost was also found to increase tremendously. Moreover, farmers were
found to ignore important steps such as proper pond bank repairing, grading,
fertilization and some even do not discern the life cycle of the species, and consequently
do not know the conditions required for its reproduction. Grow-out data for
conventional genetic improvement study and tissue samples for molecular genetic study
were collected from a farm owned by Department of Fisheries, Kg. Pulau Sayak at
Tapah village. DNA extraction and molecular genetic analysis were conducted at the
Animal Genetics and Genomics Laboratory, Division of genetics and Molecular
biology, Institute of Biological Sciences, Faculty of Science, University of Malaya. Regarding economically important characters, Kedah population showed significant
(P<.05) superiority over the other populations for harvest weight, total length, carapace
length and tail length. Moreover, heritability estimates for these characters range from
high to moderate. So, using selection methods is recommended for future improvement
of stocks. Harvest weight directly reflects product amount, therefore, multiple linear
regression approach was applied to predict it through information of the rest of growth
related traits. This model is more accurate than simple relations models. The predictors
were significant (P<.05) factors for the multiple regression equations drawn. Significant
differences between the equations according to age and sex was found. In studying the
genetic diversity of these populations, the COI gene was sequenced for samples of the
studied populations and their progenies. Forty three haplotypes were generated from
117 sequences of the parental populations; most which were unique. Genetic diversity
for studied populations fall within the range of moderate to high (0.6575-0.9206) but
nucleotide diversity was low (0.2511-1.1942%) showing subtle variation among them
(Amova 5.45%, p<.00006). Networking the haplotypes and constructing a phylogenetic
tree for only the unique ones revealed significant genetic structuring of these
populations. Cyclical mating was found to be successful in securing genetic diversity as
the genetic variability of progeny groups was high (0.7381 - 0.9412). Unique haplotypes
may be useful in identifying breeding families and help in aquaculture improvement
programs. Tajima’s neutrality test indicated significant (p<.027) departure of Negeri
Sembilan population from mutation- drift equilibrium; meaning that it may have been
losing variability. Consequently, seasonal band of fishing to replenish the species
populations in rivers of South Malay Peninsular is recommended.
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