International Journal of Aquaculture, 2015, Vol.5, No.23 1
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for captive population (Luvesuto et al., 2007; Perez-
Enriquez et al., 2009; Souza De Lima et al., 2010;
Vela-Avitúa et al., 2013) and because of that, a
Hardy-Weinberg disequilibrium is manifested for most
of the
loci
in our work and in theirs. The Fst, a
measure of interspecific variation among population is
useful in our criterion, when those populations are in
different geographical areas or when its origin in the
time is different as is the case of comparison of
descendant of different introduced stocks of
P.
vannamei
for culture (Pérez-Beloborodova et al.,
2012). That is why this parameter was not used to
estimate inbreeding among the first introduced stock
and three of its descendants.
On the other hand, Queller and Goodnight estimator
for relatedness was helpful to characterize those
stocks in present work and in previous ones (Borrell et
al., 2006; Artiles et al., 2011a; Pérez-Beloborodova et
al., 2012). Average media is not actually a good
indicator because positive and negative values rates
are obtained, but distributions for each stock offer a
general picture about consanguinity. The mode of
values is around zero or less for all the stocks, which
indicates that most of the individuals are not related
(Figure 4). Lower kurtosis is obtained in successive
generations which indicate a logical increase in
consanguinity over several generations. Besides, when
distributions were compared, statistical differences were
obtained among all stocks, except for one of the
comparisons exemplified in Figure 5 together with
another that showed significance.
The typical obtained L-shape when plotting the allele
proportion
versus
the frequency range (Figure 6)
means that not recent bottleneck effect has been
produced (Allendorf and Luikart, 2007). More allele
proportion at higher frequencies (mostly at frequency
range one) would indicate the fixation of one or more
allele at any or several
loci
, and thus, a recent bottleneck
effect. The non-existence of this effect for none of the
analyzed stocks in this work is consistent with the
acceptable levels of genetic parameters, considering
that more than ten progenies have been in culture
because the previous history of this line is unknown.
When using a similar procedure Nahavandi et al.,
2011 detected a recent bottleneck effect in Wild tiger
Shrimp
Penaeus monodon
in Malaysia, one of the
major shrimp’s producer countries in the world maybe
due to the over exploitation of this resource in natural
areas. This fact highlights the importance of using
Biotechnology in breeding programs as a tool to
recommend and to guide crossings and mattings.
2.4 General Remarks and perspectives
.
The Pacific White shrimp,
Penaeus (Litopenaeus
vannamei
) is the only shrimp cultured species nowadays
in Cuba with a total catch around 3121.4 Tons in 2295
Hm
2
. This estuarine resource constitutes an employment
source and an important economic branch to the
country. Due to the many advantages for
domestication and the globalization of this species in
the international market, all the shrimp aquaculture
industry has been focus into its culture. Fortunately
many genetic data about the Pacific white shrimp has
been generated over the world and especially in
shrimp producers’ countries.
In that way, basic and applied research could help to
support shrimp productions and to maintain this
economic and social object. This work offers a
panoramic about the descendants of the first stock
equally from the genetics and the productive point of
view comparing trends of both performances. If we
take into a consideration that no significant differences
between the first and the tenth generations for final
weight and yield were found while a significant
increase in survival was established (Figure 1), and
that genetic parameters remains more or less stable for
the tested stocks (Figure 2 and table 1), it seems that
there is not a negative influence of the inbreeding yet.
This is substantially corroborated by the non-existence
of a bottleneck effect (Figure 6) as well as by the fact
that there is not a shift in the maxima peak of
relatedness (Figure 4).
It is known that the first introduction of
P. vannamei
for culture is the most variable of the five that has
been entered into the country (Artiles et al., 2011a).
Thus, many questions still require answers and future
work, such as: what would happen with the rest of
descendants and crossings for genetic parameters and
productive traits. For that reason a genetic characterization
of the YAGUACAM’s brood stock it’s being currently
done. Another important question is how many
generations could lead to acceptable productions levels
and the real correlation among phenotypic and genetic
traits for Cuban stocks. Perez-Enriquez et al., 2009
