5Record of pregnant females of Pseudobatos horkelii.
length, total weight, liver weight, digestive tract weight,
diameter of pre-ovulatory follicles and ovarian weight
(Table 1). Females were identified as specimens #1
and #2. The total weight of female #1 was 5.63 kg and
female #2 weighed 4.78 kg. Female #1 had three
preovulatory vitellogenic follicles with a diameter of 3.5
cm, in each ovary. The combined weight of the ovaries
was 110.3 g. The individual weight of the ovaries was
not available as the follicles dissolved during extraction
and manipulation; however, the contents were included
in the use of petri dish. In individual, the left ovary was
17.9 g (one vitellogenic follicle 3.5 cm in diameter and
seven smaller 1.0 cm each). The right ovary weighed
60.4 g (three large follicles 3.5 cm in diameter each and
six smaller ones). One embryo was in individual #2,
(Fig. 3, F).
The results found show that the specimens
sampled are adult individuals (Lessa et al., 1986). The
species comes close to the coast with the objective of
reproduction, since the young are born in this region
(Vooren and Klippel, 2005). Thus, exorbitant catches
like this one, demonstrate that P. horkelii, a Critically
Endangered species, continues to be over captured,
even during the reproductive period, in the southern
coast of Brazil, were females migrate in warmer month
for parturition.
seudobatos
but
it was already in a state of decomposition
P horkelii is a viviparous species, and in
comparison to oviparous species, the viviparous
reproduction of those species depending solely on a
yolk sac, and tends to be associated with a more
moderate reproductive rate (Wourms, 1988). The
specificity of the lower reproductive rate of this species
coupled with its dependence on coastal areas for
reproductive purposes, continuously increases the
vulnerability of the local population (Vooren and
Klippel, 2005). In addition, although actual legislation
avoids the capture and landing of this species, illegal
catches are still a fact, as is the case in the present
report.
The guitarfishes have been steadily declining over
time. In 2014, the group was identified as one of the
most susceptible elasmobranch families to fisheries,
along with sawfishes (Dulvy et al., 2014). It is evident
that these fishes are highly vulnerable in shallow
coastal ecosystems, as they are easily accessible to
intensive fishing practices. This could be the primary
reason why the vast majority of guitarfishes
populations are facing severe threats all over their
distribution areas (Moore, 2017).
Once fish populations collapse, potential stock
recovery is a time-consuming process, even if fishing
pressure is reduced (Hutching and Reynolds, 2004).
Furthermore, at a global level, substantial declines in
guitarfishes populations have already been
documented, along with the disappearance of some
species elsewhere (Carlisle et al., 2007; Diop and
Dossa, 2011). The partnership between scientists and
conservation-focused organizations represents a
valuable synergy that combines scientific knowledge,
practical resources, and field efforts to effectively
safeguard critically threatened species as the
guitarfishes.
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