Boletín de la Sociedad Zoológica del Uruguay, 2023
Vol. 32 (1): e32.1.4
ISSN 2393-6940
https://journal.szu.org.uy
DOI: https://doi.org/10.26462/32.1.4
ABSTRACT
In this article, the capture of two pregnant females of the
Brazilian Guitarfish, Pseudobatos horkelii, is recorded.
Although the species is Critically Endangered and it
capture is prohibited, the illegal catches occur
nevertheless.
Key words: Chondrichthyes, Pseudobatidae, fishes,
predatory fishing.
RESUMEN
En este artículo se registra la captura de
dos hembras gestantes de la raya viola, Pseudobatos
horkelii. Aunque la especie está en Peligro Crítico de
extinción y su pesca está prohibida, las capturas
continúan ocurriendo de forma ilegal.
Palabras clave: Condrictios, Elasmobranquios,
peces, pesca depredadora.
The Family Rhinobatidae comprises six genera
with 45 species (Nelson, 2016), one of these species is
the guitarfish Pseudobatos horkelii (Muller and Henle,
1841), which can be found from the coast of the state of
Bahia in Brazil, to Uruguay and Argentina (Compagno,
1999; Menni and Stehmann, 2000). In general, this
species inhabits benthic environments of the
continental shelf, on sandy or muddy bottoms and
occurs throughout the year, being a resident species
(Vooren, 1997). The southern shelf is the only area
within its geographic distribution with a high abundance
Registro de hembras gestantes de Pseudobatos
horkelii (Muller & Henle, 1841), una raya guitarra en
peligro crítico aguas afuera del Atlántico
Sudoccidental.
of this species (Vooren and Klippel, 2005).
Pseudobatos horkelii is a yolk sac viviparous species
(Lessa et al., 1986; Wourms, 1988), i.e., the embryo
develops mainly through the yolk available in the
mature oocyte, but other nutritional sources have
recently been discovered (Wosnick et al., 2022). On the
continental shelf of southern Brazil, the reproductive
cycle is synchronized at the population level, so that
adult females give birth at the same time of the year.
The time of birth corresponds to the months of
February and March, when females are able to
copulate soon after giving birth, and a new pregnancy
occurs (Vooren and Klippel, 2005).
Pseudobatos horkelii is globally classified by the
International Union for Conservation of Nature (Pollom
et al., 2020) as "Critically Endangered" (CR), the same
status for the Brazilian regional assessment. According
to the Ministry of Environment (MMA), the capture of P.
horkelii is prohibited by National Legislation (Law
10.683) in the States of Rio de Janeiro, São Paulo,
Paraná, Santa Catarina, and Rio Grande do Sul
(IBAMA, 2004), though some studies show these
catches using molecular approaches (De Franco et al.,
2012; Alvarenga et al., 2021). Even so, either by
accidental or illegal capture, individuals continue to be
captured. Thus, it is of utmost importance to create,
implement, and maintain projects resulting from
networked partnerships between the academic
community and environmental protection agencies,
which aim at the conservation of this and other
endangered species. The extension project ICB/FURG
in partnership with the Environmental Patrol of the
Military Brigade (PATRAM) - PROPESP registration
number EXT109 - "Implementation of the regulations
prohibiting fishing and landing of endangered species
of Chondrichthyes in the State of Rio Grande do Sul",
represents a collaboration to formalize the production
Bol. Soc. Zool. Uruguay (2ª época). 2022. ISSN 2393-6940Vol. 32 (1): e32.1.4
RECORD OF PREGNANT FEMALES OF Pseudobatos horkelii (MULLER & HENLE, 1841), A CRITICALLY
ENDANGERED GUITARFISH OFF SW ATLANTIC
Yan Gowert* y Maria Cristina Oddone
yangowert@furg.br
Fecha de recepción: 19 de enero de 2023
Fecha de aceptación: 30 de mayo de 2023
.
Universidade Federal do Rio Grande, Instituto de Ciências Biológicas, Setor de Morfologia/Pesquisa em
Chondrichthyes, Av. Itália, Km 8 s/n, Campus Carreiros, 96203-900 Rio Grande, RS, Brasil
*Corresponding author:
2
Yan Gowert* y Maria Cristina Oddone
of technical reports of species identification to detect
the capture of endangered species. The objective of
this work is to record an illegal and intentional fishing
event where there was a massive capture of pregnant
females of P. horkelii, in the South of Rio Grande do Sul,
in Southern Brazil, SW Atlantic.
The seizure occurred on 12/22/2018 in the city of
São José do Norte (32º 00' 53" S and 52º 02' 30" W)
(Fig. 1), the number of specimens of P. horkelii found
was 2,134, totaling approximately 10,000 kg. The
fishing gear was a bottom trawl, which was pulled
manually from a motor boat. Once landed, the
Fig. 1. Map of the study area, Mar Grosso beach in the municipality of São José do Norte, Rio Grande do Sul, Brazil, where
the capture of about 10 tons of Pseudobatos horkelii was carried out on 12/22/2018.
Table 1. Measured variables with their respective values. Total length (CT), liver weight (LW), digestive tract weight (DTW), follicle
diameter (FD), ovary weight (OW) and total weight (TW). P. horkelii specimens collected on 12/22/2018 at mar grosso beach, in the city of
São José do Norte, Brazil.
Specimens CT (cm) LW (g) DTW (g) FD (cm) OW (g) TW (g)
#1 117.0 181 83 3.5 110.3 5630
#2 113.0 202 80 3.5 L: 17.9; R: 60.4 4780
Bol. Soc. Zool. Uruguay (2ª época). 2022. ISSN 2393-6940Vol. 32 (1): e32.1.4
3Record of pregnant females of Pseudobatos horkelii.
Fig. 2. Moment when part of the Pseudobatos horkelii catch was collected. A total of 2,134
specimens were captured (A). Dorsal view of pregnant female of Pseudobatos horkelii (B).
Ventral view of pregnant female of P. horkelii (C).
Bol. Soc. Zool. Uruguay (2ª época). 2022. ISSN 2393-6940Vol. 32 (1): e32.1.4
Yan Gowert* y Maria Cristina Oddone
specimens were removed from the net and
immediately placed on a track for transport and
marketing moment when the seizure occurred. On
March 1, 2019, PATRAM donated two of the seized
individuals for species identification and biological
sampling. The specimens were taken to the
Morphology II Instituto de Ci ncias
Biológicas, FURG, for further analysis. Taxonomic
identification of individuals followed Vooren and Klippel
(2005). Biological sampling included the record of total
laboratory at the ê
4
Fig. 3. Ventral view of the abdominal cavity of individual #1 after removal
of the digestive system, ovaries full of mature vitellogenic follicles (A).
Appearance of the gravid uteri after removal of the ovaries (B). Tertiary
membrane of the egg (C). Uterus contents, showing uterine egg yolk
and tertiary membrane. Right (above) and left uterus (below), the
anterior region of the oviduct is oriented to the left, where the oviductal
glands can be seen (E). Embryo removed from one of the uteri, showing
external branchial filaments and without pigmentation (F).
Bol. Soc. Zool. Uruguay (2ª época). 2022. ISSN 2393-6940Vol. 32 (1): e32.1.4
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.
REFERENCES
Alvarenga, M., Solé-Cava, A.M., y Henning, F. (2021).
What's in a name? Phylogenetic studies species
identification reveals extensive trade of
endangered guitarfishes and sharks, Biological
Conservation, 257.
Carlisle, A., King, A., Cailliet, G.M., y Brennan, J.S.
(2007). Longterm trends in captch composition
from elasmobranch derbies in Elkhorn Slough,
California. Marine Fisheries Review, 69, 25–45.
Compagno, L.J.V. (1999). Checklist of living
elasmobranchs. En: Hamlett, W.C (Eds.)
Sharks, Skates, and Rays: The Biology of
Elasmobranch Fishes. John Hopkins University
Press, Maryland.
De Franco, B.A., Mendonça, F.F., Oliveira, C., y
Foresti, F. (2012). Ilegal trade of the guitarfish
Rhinobatos horkelii on the coasts of central and
Southern Brazil: genetic identification to aid
conservation. Aquatic Conservation: Marine
and Freshwater Ecosystems, 22(2), 272–276.
Diop, M., y Dossa, J. (2011). 30 years of Shark fishing in
West Africa: Development of fisheries, catch
trends and their conservation status in Sub-
regional Fishing Commission member
countries. FIBA.
Dulvy, N.K., Davidson, L.N., Kyne, P.M.,
Simpfendorfer, C.A., Harrison, L.R., Carlson,
J.K., y Fordham, S. V. (2016). Ghosts of the
coast: global extinction risk and conservation of
sawfishes. Aquatic Conservation: Marine and
Freshwater Ecosystems, 26(1), 134–153.
Hutchings, J.A., y Reynolds, J.D. (2004). Marine fish
population colapses: Consequences for
recovery and extinction risk. BioScience, 54(4),
297–309
Instituto Brasileiro de meio ambiente e dos recursos
naturais renováveis. (2004). Instrução
Normativa do Ministério do Meio Ambiente n 5,
de 21 de maio de 2004. Recuperado de
https://www.ibama.gov.br/sophia/cnia/legislaca
o/MMA/IN0005-210504.PDF
Lessa, R.P., Vooren C.M., y Lahaye J. (1986).
Desenvolvimento e ciclo sexual das fêmeas,
migrações e fecundidade da viola, Rhinobatos
horkelii (Muller & Henle, 1841) do Sul do Brasil.
Atlântica, 8, 5–34.
Menni, R.C., y Stehmann, M.F. W. (2000). Distribution,
environment and biology of batoid fishes off
Argentina, Uruguay and Brazil, a review.
Revista del museo Argentino de ciencias
naturales, 2(1), 69–109
Bol. Soc. Zool. Uruguay (2ª época). 2022. ISSN 2393-6940Vol. 32 (1): e32.1.4
Yan Gowert* y Maria Cristina Oddone
Moore, A.B. (2017). Are guitarfishes the next
sawfishes? Extinction risk and an urgent call for
conservation action. Endangered Species
Research, 34, 75–88
Nelson, J.S., Grande T.C., y Wilson M.V. (2016). Fishes
of the world, New Jersey, USA: John Wiley &
Sons.
Pollom, R., Barreto, R., Charvet, P., Chiaramonte,
G.E., Cuevas, J.M., Herman, K., ... Rincon, G.
(2020). Pseudobatos horkelii, Brazilian
guitarfish. CONICET.
Vooren, C. M. (1997). Demersal elasmobranchs. En:
Seeliger, U., Odebrecht., C y Castello, J. P
(Eds.) Subtropical convergence environments:
the coast and the sea in the Southwestern
Atlantic. Demersal elasmobranchs. Berlim:
Springer-Verlag, 141–146.
Vooren, C.M., Lessa, R.P., y Klippel S. (2005). Biologia
e status de conservação da viola Rhinobatos
horkelii. En: Vooren, C. M y Klippel, S (Eds.)
Ações para a conservação de tubarões e raias
no sul do Brasil (pp, 33–56). Porto Alegre, Brasil:
Igaré
Wosnick, N., Leite, R.D., Giareta, E.P., Morick, D., y
Hauser-Davis, R.A. (2022). Unraveling
metabolite provisioning to Offspring through
parental fluids: a case study of the Brazilian
Guitarfish, Pseudobatos horkelii. Frontiers in
physiology, 13.
Wourms J.P., Grove B.D., y Lombardi J. (1988). The
maternal-embryonic relationship in viviparous
fishes. Fish physiology. Academic Press,
1–134.
Editor de Sección: Marcelo Loureiro
6
Bol. Soc. Zool. Uruguay (2ª época). 2022. ISSN 2393-6940Vol. 32 (1): e32.1.4