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International Journal of Aquaculture, 2014, Vol.4, No.09, 55
-
63
http://ija.sophiapublisher.com
55
Research Article Open Access
Assessment of Genetic Variability of Prawn (
Macrobrachium rosenbergii
) Post
Larvae (PL) from the Broods Stocked under Different Sex Ratios
Sk. Shahinur Islam
1
, Md. Saifuddin Shah
2
, Md. Lifat Rahi
2
1. Research Centre for Experimental Marine Biology and Biotechnology, University of the Basque Country, Spain
2. Fisheries and Marine Resource Technology Discipline and Vice-chancellor, Khulna University, Khulna-9208, Bangladesh
Corresponding author email
International Journal of Aquaculture, 2014, Vol.4, No.09 doi: 10.5376/ija.2014.04.0009
Received: 21 Jan., 2014
Accepted: 27 Feb., 2014
Published: 22 Mar., 2014
Copyright © 2014
Islam et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Islam et al., 2014, Assessment of Genetic Variability of Prawn (
Macrobrachium rosenbergii
) Post Larvae (PL) from the Broods Stocked under Different Sex
Ratios, International Journal of Aquaculture, Vol.4, No.09: 55-63 (doi: 10.5376/ija.2014.04.0009)
Abstract
The giant freshwater prawn (
Macrobrachium rosenbergii
) culture in Bangladesh is now at stake due to slower growth
performance. The aim of the present study was to assay the impact of sex ratio on the genetic variability of larvae produced from the
broods stocked under different sex ratios by analyzing Randomly Amplified Polymorphic DNA (RAPD) of
M. rosenbergii
. Broods
were stocked under 3 different sex ratios viz., 1♂: 1♀, 1♂: 2♀ and 2♂: 1♀. A control population was also kept that involved the
larvae production from the broods of natural source. The RAPD analysis generated 88 distinct bands of which 36 (41%) bands were
polymorphic. The percentages of polymorphic loci were found to be 32%, 48%, 24% and 52% for the sex ratios 1♂: 2♀, 1♂: 1♀, 2♂:
1♀ and Control respectively. The pair wise genetic distances were 0.010, 0.007, 0.021, 0.016, 0.026 and 0.008 for 1♂: 1♀ vs. 1♂: 2♀,
1♂: 1♀ vs. Control, 1♂: 1♀ vs. 2♂: 1♀, 1♂: 2♀ vs. Control, 2♂: 1♀ vs. Control and 1♂: 2♀ vs. 2♂: 1♀ respectively. Overall gene
diversity for all loci was 0.10. The unweighted pair group method of arithmetic mean (UPGMA) dendrogram based on Nei’s genetic
distances clearly showed the severance of four different experimental groups into two clusters: 1♂: 1♀ and control in one and 1♂:
2♀ and 2♂: 1♀ in the other cluster. Results of the present study revealed that 1♂: 1♀ sex ratio is appropriate to establish the brood
banks and for maintaining genetic variation in the offspring.
Keywords
Giant freshwater prawn; Genetic variability; Sex ratios; Polymorphism
Introduction
The giant freshwater prawn (
Macrobrachium
rosenbergii
) is one of the most important crustacean
species produced in inland aquaculture in many
tropical and subtropical countries worldwide. The
world’s total farmed
M. rosenbergii
production was
over 205,033 tons (market value exceeded US$ 896
million), of which 99% was produced in Asia (New,
2005). Shrimp aquaculture is one of the fastest
growing economic activities in coastal areas of the
Asia-Pacific region and Bangladesh is an impressive
contributor in the global cultured shrimp industry;
sixth largest producer in the world (Gjedrem et al.,
2012). Shrimp farming in Bangladesh has been
expanding since the early 1970s and reached an
industrial scale followed by increasing demand for
shrimp in the export market (Islam et al., 2004); there
has been a very rapid global expansion of freshwater
prawn farming since 1995. In early 1990s, 8306
hectare area was being used for
Macrobrachium
culture in Bangladesh using wild fry (Ahmed et al.,
2008) but recently the area has been raised to 40,000
ha (Amrit and Yen, 2003). With the increasing
demand for food fish and decline in capture fisheries
production, aquaculture in Bangladesh is heading
towards intensification. This shift from low-density to
high-density culture,
i.e
., traditional to semi-intensive
or intensive culture, is consequently leading to an
unprecedented rise in the demand for good quality
seed (post larvae) and feeds. Bangladesh has a unique
and favorable environment for prawn culture.
Presently
M. rosenbergii
is commercially cultured
only in the coastal districts but there is a great
potential for successful prawn culture in the numerous
ponds of Bangladesh. This species grows faster in
suitable environmental conditions and attain
marketable size within 6 months, while fin fishes
require at least 1 year (Hossain and Paul, 2007).
Recent problems encountered by the brackish water
shrimp industry led to the boost for the culture of
freshwater prawns. The culture of
M
.
rosenbergii
is
traditionally being performed in ponds (Weimin and