International Journal of Aquaculture, 2015, Vol.5, No.23 1
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12
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This is the first work that documents both tendencies
for the first introduced stock in Cuba for culture of
P.
vannamei
and some of its descendants.
2.1 Productive marker tendencies of four descendant
of the first founder stock of
P. vannamei
in Cuba
for culture.
The intentional introduction of
P. vannamei
in Cuba
greatly increased the productive markers in the
Enterprise Base Units (EBUs). Since 2006, these
productive estimators have been showing irregularities
as a consequence of culture system handling problems,
mainly in food supply and nutritional content.
In fact, the fall in survival and yield for the ninth
progeny of the founder stock, S9-1, could be due to a
wrong handling process in grow out ponds for this
culture cycle, specifically in food supply and quality
of it. In a controlled experiment, Gaxiola et al., 2006
demonstrated that the change in diet composition have
a long term effect in growth and survival of this
species. In the present case, a change in the artificial
diet (ECCAM, 2014, private communication) could
lead to a decline in both productivity markers.
Even though significant differences were not detected
for the final weight, a slight increase of the mean
value (15 g) in the ninth offspring is observed at 120
culture days (Figure 1). In similar conditions in
commercial culture ponds in Peru, using certified
seeds from Ecuadorian laboratories, and good quality
food supply, a final weight of 22 g was obtained
(Mendoza-Ramirez, 2011).
The obtained values of survival for the first, second
and tenth progenies of the first introduced stock (S1-1,
S2-1 and S10-1) are higher than 50 %, comparable to
two reports in USA (Sookying et al., 2011; Treece,
2015) and two studies in Costa Rica as well (Valverde-
Moya and Alfaro-Montoya, 2013; 2014). Two main
reasons could explain this. The first one is the origin
of the lines. All stocks from SIS are Shrimp Pathogen
Free (SPF) and besides, this imported line (The first
introduction) was genetically manipulated for high
growth (Tizol et al., 2004). The second one is the
caring handling and the maintenance of a Sanitary
Surveillance Program (Silveira, 2006) that avoids the
viral diseases occurrence in Cuba since the introduction
of
P. vannamei
(Artiles et al., 2011b).
The yield overcomes the 900 Kg/Hm
2
/cycle, which is
below the world standard average for the semi intensive
culture. However, similar yields have been reported by
some authors from Latin America region. That is the case
of farms in Brazil (893.3 Kg/Hm
2
/cycle) and a final
weight of 11.3 g in 85 days in culture (Nunes et al., 2014)
and Costa Rica (868 Kg/Hm
2
/cycle) at 120 days in
culture (Valverde-Moya and Alfaro-Montoya, 2014).
Another report from Brazil is nearer of the average world
standard, reaching 4.457 to 5.012
Kg/Hm
2
/cycle,
considered as a good profitable production level for this
country (Alvino et al., 2014).
2.2 Genetic parameters
tendencies of the first
introduced stock of
P. vannamei
in Cuba for culture
and three descendants.
There is an established consensus in shrimp genetic
research that there is a decrease in genetic diversity
parameters from wild to cultured shrimp stocks. For
many penaeid species it has been very well documented
with the use of different markers (Benzie, 2000; Xu et al.,
2001; Meehan et al., 2003).
On the other hand, when comparing among generations
in culture, although most of the authors do not find a
significant variation (Cruz et al., 2004; Luvesuto et al.,
2007; Perez-Enriquez et al., 2009), one researchers’
group does find a non-significant decrease although
using different parameters, but employing microsatellites
and pedigree information (Vela-Avitúa et al., 2013). In
present work, a mix of those results has been obtained.
In accordance with those authors, observed and expected
heterozygosities (Ho and He respectively) are similar
(Table I for values and significances and Figure 1 for
tendency), with no drastic variations among generations.
This is not surprising, since some authors have stayed
that heterozygosity is an imperfect measure of genetic
variability (Cruz et al., 2004; Souza De Lima et al.,
2010) because high values of that parameter could be
obtained with as few as two different alleles. Besides
of that, Luikart et al., 2010 showed that He is less
sensitive than allelic diversity when assessed soon
after bottleneck. Neither surprising is the fact that as
well as for the same cited authors, populations for
most of the loci are in Hardy-Weinberg disequilibrium.
This has been also widely documented for captive
populations that do not strictly fit themselves to the
statements of this law,
e.g
: Cruz et al., 2004; Luvesuto
