Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-22T13:05:07.199Z Has data issue: false hasContentIssue false

Revealing further insights on extralimital records of Burmeister's porpoise (Phocoena spinipinnis, Burmeister, 1865) in the Southwestern Atlantic Ocean

Published online by Cambridge University Press:  29 October 2024

R. R. Carvalho*
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
J. Ikeda
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
Y. Daoualibi
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
E. B. Guari
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
P. Teixeira
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
E. B. Santos-Neto
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
J. Lailson-Brito
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
L. Barbosa
Affiliation:
Instituto ORCA, Guarapari, Espírito Santo, Brazil
M. Ramos-Nogueira
Affiliation:
Instituto ORCA, Guarapari, Espírito Santo, Brazil
A. F. Azevedo
Affiliation:
Laboratório de Mamíferos Aquáticos e Bioindicadores, Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
*
Corresponding author: R. R. Carvalho; Email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Burmeister's porpoise (Phocoena spinipinnis) is an endemic species found in both the South Pacific and Atlantic Oceans, along the coastal regions of South America. In the Southwestern Atlantic Ocean, the species is reported from Tierra del Fuego, Argentina to Santa Catarina, Brazil, and the Falkland Islands. This study provides new insights on two stranded P. spinipinnis specimens in Southeastern Brazil, including the first occurrence in the state of Rio de Janeiro. Despite the advanced decomposition of the carcasses, which limited necropsy findings, we provide new data on the general characteristics of the specimens found in this extralimital geographical range, such as total body length, age, sex, vertebral count, and cranial measurements.

Type
Marine Record
Copyright
Copyright © The Author(s), 2024. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom

Introduction

Burmeister's porpoise (Phocoena spinipinnis) is an endemic species found along the eastern and western coasts of South America. It ranges from Bahía de Paita, Peru (05°01'S) to Chile (42°30'S) in the west, and from Tierra del Fuego, Argentina (42°23'S) to Santa Catarina, Brazil (28°48'S) in the east (Brownell and Praderi, Reference Brownell and Praderi1984; Guerra et al., Reference Guerra-Correa, Van Waerebeek, Kandora and Jorquera1987; Simões-Lopes and Ximenes, Reference Simões-Lopes and Ximenez1989; Van Waerebeek et al., Reference Van Waerebeek, Santillan and Reyes2002). Recently, Weir and Rutherford (Reference Weir and Rutherford2019) reported a stranded specimen of P. spinipinnis in the Falkland Islands (51°40.9'S) in the Patagonian Continental Shelf, a region not previously considered within the species’ geographical range. Throughout its distribution, the species is more commonly reported in shallow inshore waters, although observations of individuals 20–50 km offshore have also been confirmed (Corcuera et al., Reference Corcuera, Monzón, Crespo, Aguilar and Raga1994; Clay et al., Reference Clay, Mangel, Alfaro-Shigueto, Hodgson and Godley2018; Santillán, Reference Santillán2022).

Like many cetaceans, the occurrence of P. spinipinnis is associated with various environmental features in both the southeast Pacific and southwest Atlantic coasts of South America, such as local currents, upwelling events, and contributions from continental runoff (Molina-Schiller et al., Reference Molina-Schiller, Rosales and de Freitas2005). The northern geographical limits on both sides of South America are influenced by the cold waters of the Humboldt Current in Peru and the Falkland/Malvinas Current in Uruguay and Brazil (Reyes and Van Waerebeek, Reference Reyes and Van Waerebeek1995; Molina-Schiller et al., Reference Molina-Schiller, Rosales and de Freitas2005). Although the holotype specimen was found in the La Plata River, Argentina, in 1865 (Burmeister, Reference Burmeister1865; Brownell and Praderi, Reference Brownell and Praderi1984), most knowledge about the species has come from stranded or by-caught specimens, due to its elusive and inconspicuous swimming behaviour and tendency to form small groups (Brownell and Praderi, Reference Brownell and Praderi1984; Corcuera et al., Reference Corcuera, Monzon, Aguilar, Borrell and Raga1995; Goodall et al., Reference Goodall, Würsig, Würsig, Harris and Norris1995a; Reyes and Van Waerebeek, Reference Reyes and Van Waerebeek1995; Rosa et al., Reference Rosa, Milinkovitch, Van Waerebeek, Berck, Oporto, Alfaro-Shigueto, Van Bressem, Goodall and Cassens2005; Garcia-Godos et al., Reference Garcia-Godos, Van Waerebeek, Reyes, Alfaro-Schigueto and Arias-Schreiber2007; Galatius et al., Reference Galatius, Berta, Frandsen and Goodall2011; Weir and Rutherford, Reference Weir and Rutherford2019; Marchesi et al., Reference Marchesi, Galatius, Zaffino, Coscarella and González-José2022; Padula et al., Reference Padula, Machado, Milmann, de León, Gana, Wickert, Argañaraz, Bastida, Rodríguez and Denuncio2023).

The first records of P. spinipinnis along the Brazilian coast date back to the mid- to late 1980s (Pinedo, Reference Pinedo1989; Simões-Lopes and Ximenez, Reference Simões-Lopes and Ximenez1989) when stranded carcasses were reported in the states of Rio Grande do Sul and Santa Catarina (28°48'S) (Figure 1). This extended the known distribution northward by 900 km from its previously known range in Uruguay. A few decades later, a record of P. spinipinnis was reported in Anchieta, Espírito Santo, southeastern Brazil, with no further details provided other than the geographical location of the stranding (Mayorga et al., Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020). This has remained the northernmost occurrence for the species in the southwestern Atlantic Ocean.

Figure 1. Previously known northernmost range of Phocoena spinipinnis in the Southwestern Atlantic Ocean (SWAO) in Santa Catarina state (SC) (black dot), new occurrence reported in this paper (red star) in Rio de Janeiro state (RJ) 930 km northward, and the occurrence reported in Mayorga et al. (Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020) in Espírito Santo State (ES) (black star). The monitoring areas for PMP-BS and Instituto Orca are represented by coastal orange and red polygons, respectively.

Based on two stranded carcasses found in 2014 and 2021, this study provides additional information on the occurrence of P. spinipinnis in southeastern Brazil in the southwestern Atlantic Ocean. It describes necropsy findings for the specimen previously reported in Anchieta by Mayorga et al. (Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020) and a new stranding in the state of Rio de Janeiro.

Materials and methods

The Laboratório de Mamíferos Aquáticos e Bioindicadores at Universidade do Estado do Rio de Janeiro (MAQUA/UERJ) is one of the institutions that monitors marine mammal strandings along approximately 1160 km of the central-south coast of the state of Rio de Janeiro in southeastern Brazil. Since 2017, a monitoring programme, the ‘Projeto de Monitoramento de Praias da Bacia de Santos (PMP-BS)’ has been conducted along the southern and southeastern Brazilian coast. This programme was established to meet the requirements of the federal environmental licensing institute, ‘Instituto Brasileiro do Meio Ambiente e Recursos Renováveis’ (IBAMA), for oil and natural gas production and extraction in the Santos Basin. The aim of PMP-BS is to assess the potential impacts of oil and gas activities on seabirds, sea turtles, and marine mammals through beach stranding monitoring, veterinary care to live animals, and necropsies of deceased individuals. The project covers 15 stors from Laguna/Santa Catarina to Saquarema/Rio de Janeiro, spanning southern to southeastern Brazil (Figure 1). The MAQUA/UERJ team is specifically responsible for collecting and conducting necropsies on stranded marine mammal carcasses in sectors 11–15, which encompass the south to central Rio de Janeiro State (Petrobras, 2023). Carcasses are typically reported through two methods: (1) active beach monitoring by technicians and researchers, who search for carcasses, or (2) reports from residents, visitors, tourists, or anyone in coastal areas who voluntarily report strandings, primarily through institutional phone numbers.

On 2 April 2021, residents of Praia da Vila, Saquarema municipality (22°54’4”W; 42°29’54”S) (Figure 1) reported a stranded dolphin carcass identified by the field team as P. spinipinnis. The total body length (TBL), sex, body condition, decomposition code, and photographs were taken in the field to document the in situ conditions of the specimen as found by the research team. The decomposition code was recorded following Geraci and Lounsbury (Reference Geraci, Lounsbury and Yates2005). The carcass was subsequently taken to the MAQUA/UERJ laboratory, where a necropsy was performed on 14 April 2021.

On 25 June 2014, a stranded carcass of P. spinipinnis was found in Praia de Parati, Anchieta municipality, Espírito Santo (see Mayorga et al., Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020 for detailed methods). Necropsy was performed on 1 July 2014.

Necropsies were performed by trained personnel, including marine mammal veterinarians. Teeth were collected in order to estimate age by the dentine growth layer groups (GLGs) (Perrin and Myrick, Reference Perrin and Myrick1980; Hohn et al., Reference Hohn, Scott, Wells, Sweeny and Irvine1989).

To evaluate vertebral count and cranial measurements, the carcass remains were macerated for approximately 120 days until the skeleton was completely free of tissue residue. The skeleton was then cleaned with mild soap and a brush, followed by air-drying under ambient conditions.

Thirty cranial measurements were taken using a 300 mm Vernier caliper, following Perrin (Reference Perrin1975) and Goldin and Vishnyakova (Reference Goldin and Vishnyakova2015). Some measurements described by Perrin (Reference Perrin1975) were not feasible due to the loss of specific parts of the skull.

Similar stranding monitoring is also conducted by Instituto ORCA, which collects stranded carcasses along approximately 260 km of the state of Espírito Santo coast in southeastern Brazil (methods described in Mayorga et al., Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020) (Figure 1). The characteristics of the specimen stranded in Anchieta, Espírito Santo and first reported by Mayorga et al. (Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020), were also described based on necropsy findings. However, age, vertebral count, and cranial measurements were not determined for this specimen.

Results

In situ observations in Praia da Vila revealed an almost entirely skinless carcass of Phocoena spinipinnis, measuring 154 cm of TBL, and in late decomposition (code 4 according to Geraci and Lounsbury, Reference Geraci, Lounsbury and Yates2005), with missing eyes and partially macerated jaws (Figure 2). Four suggestive post-mortem shark bites were also observed: A – genital slit (27 cm × 11.5 cm); B – umbilicus/thoracic cavity (21 cm × 11.5 cm); C – right ventral lateral thorax (29 cm × 11.5 cm); and D – ventral portion of the head (cervical to zygomatic arch) (20 cm × 11.5 cm) (Figure 2).

Figure 2. Stranded Burmeister's porpoise, Phocoena spinipinnis, in the states of Rio de Janeiro (A–C) and Espírito Santo (D), southeastern Brazil. (A) Head with partially macerated left jaw, ventral laceration by suggestive post-mortem shark bites, presence of teeth and absence of the left eye; (B) Suggestive post-mortem shark bites on umbilicus/thoracic cavity and genital slit; (C) Low, triangular-shaped canted backward dorsal fin; (D) Specimen found stranded in Praia de Parati, Anchieta, Espírito Santo.

Despite its advanced decomposition, necropsy revealed a male specimen confirmed by the preservation of the penis (Figure 3). The stomach was absent, preventing any analysis of its contents. Autolysis had compromised all organs, including those of the respiratory, cardiovascular, reproductive (testicles), endocrine, lymphatic, haematopoietic, and nervous systems, making further investigation impossible. Teeth were preserved, totaling to 15 and 17 pairs in both lower and upper jaws, respectively (Figure 3).

Figure 3. Specimen of Burmeister's porpoise, Phocoena spinipinnis, stranded in the state of Rio de Janeiro, southeastern Brazil in April 2021, during necropsy (A) and evidence of penis (B) and teeth (C).

The vertebral count was 7 cervical (Cv) (Cv1–3 fused), 13 thoracic (Th), 15 lumbar (L), and 27 caudal vertebrae (Cd) (Figure 4). Except for a few caudal vertebrae, epiphyses were not fused. There were also 13 pairs of ribs, with articulations present on the first eight pairs. The age was estimated to be 3 years based on the count of growth layer groups (GLGs). Table 1 shows the 30 cranial measurements obtained from the specimen sampled in Rio de Janeiro.

Figure 4. Vertebral structure of a Burmeister's porpoise, Phocoena spinipinnis, stranded in the state of Rio de Janeiro, southeastern Brazil in April 2021. Cv – cervical; Th – thoracic; Lb – lumbar and Cd – caudal. Scale bars: 5 cm.

Table 1. Skull measurements (mm) of a Burmeister's porpoise (Phocoena spinipinnis) specimen stranded in Praia da Vila, Saquarema, Rio de Janeiro, southeastern Brazil in April, 2021

Necropsy observations of the P. spinipinnis specimen found on Praia de Parati, Anchieta municipality, Espírito Santo reported a 162 cm male individual in a late decomposition state (Figure 2), with small patches of preserved skin tissue on the caudal peduncle and the tip of the dorsal fin; eyes were absent and internal organs exhibited gas formation. Two unidentified teleost fishes were found in the stomach content. The testicles measured between 12 and 15 cm each. Teeth were preserved, adding up to 13 and 17 pairs in both lower and upper jaws, respectively (Figure 5).

Figure 5. Dorsal, ventral, and lateral view of the skull, and inner and outer side of the left mandible of a Burmeister's porpoise, Phocoena spinipinnis, stranded in the state of Rio de Janeiro, southeastern Brazil, in April 2021. Scale bars: 5 cm.

Discussion

We report here the two northernmost occurrences of P. spinipinnis in the Southwestern Atlantic Ocean to date and the first record of the species in Rio de Janeiro State, to our knowledge. This phocoenid species is described as not exceeding a total body length of more than 200 cm (Goodall et al., Reference Goodall, Würsig, Würsig, Harris and Norris1995a). One of the main characteristics of P. spinipinnis described by Goodall et al. (Reference Goodall, Würsig, Würsig, Harris and Norris1995a) is the blunt head without a distinct beak, with the forehead dropping rather abruptly to the rostrum tip. Additionally, the species is noted for a short gape and eyes positioned forward of the blowhole. In addition to the spatulate teeth typical to phocoenids, one of the species’ diagnostic features is the low, triangular canted backward dorsal fin located posterior to the midpoint of the body and covered with tiny tubercles similar to spines on its leading edge.

Due to the advanced stage of carcass decomposition, we were unable to determine the coloration of either specimen. However, in both cases, the presence of spatulate teeth, the blunt head, and the distinctive dorsal fin shape matched the previously described characteristics of P. spinipinnis, making misidentification highly unlikely. The vertebral count for the Rio de Janeiro specimen was similar to that previously reported in the literature (Brownell and Praderi, Reference Brownell and Praderi1984; Reyes, Reference Reyes, Würsig, Thewissen and Kovacs2018), although a lower number of caudal vertebrae was observed in this study. Additionally, we could not rule out some skeletal loss due to shark bites, despite the specimen appearing to be well preserved.

The total body length and epiphyseal fusion, observed in less than 10% of the vertebral column, suggest a physically immature individual in Rio de Janeiro (Corcuera et al., Reference Corcuera, Monzon, Aguilar, Borrell and Raga1995; Reyes and Van Waerebeek, Reference Reyes and Van Waerebeek1995). Male P. spinipinnis were previously reported to not attain sexual maturity between 158 and 175 cm (Goodall et al., Reference Goodall, Würsig, Würsig, Harris and Norris1995a; Reyes and Van Waerebeek, Reference Reyes and Van Waerebeek1995). However, Corcuera et al. (Reference Corcuera, Monzon, Aguilar, Borrell and Raga1995) observed physically mature male specimens at 169 cm and 3 + GLGs. At this stage, the authors also reported a vertebrae fusion of more than 40%, contrasting with our findings for the studied specimen. An important observation regarding the skull of the Rio de Janeiro specimen is that it was clearly not fully fused, suggesting an immature individual with a condylobasal length attaining 272 mm. In contrast, Molina-Schiller (Reference Molina-Schiller2006) reported that males attain physical maturity when the condylobasal length is ⩾266 mm. Although this difference may be due to geographic variations among populations, the authors did not have a sufficient sample size from Brazilian waters (n = 2) to confirm significant differences. Recent data on maturity for P. spinipinnis reported pubescent individuals ranging from 142 to 154 cm (Vega et al., Reference Vega, Van Waerebeek, Alfaro-Shigueto, Reyes and Van Bressem2022), providing further evidence to classify the maturity status of the Rio de Janeiro specimen. Accounting for total body length, the specimen found in Espírito Santo could be classified as mature according to previous studies (Goodall et al., Reference Goodall, Würsig, Würsig, Harris and Norris1995a; Reyes and Van Waerebeek, Reference Reyes and Van Waerebeek1995). Furthermore, Vega et al. (Reference Vega, Van Waerebeek, Alfaro-Shigueto, Reyes and Van Bressem2022) reported mean testicle and total body lengths of 119.4 mm and 166.39 cm, respectively, which corroborate findings for the Espírito Santo specimen.

Although the carcasses were highly decomposed, it seems unlikely that they drifted from its known previous northernmost range in southern Brazil (Simões-Lopes and Ximenez, Reference Simões-Lopes and Ximenez1989) to the states of Rio de Janeiro and Espírito Santo, which are 930 and 1280 km further north, respectively. The strandings were reported right after the end of the austral summer in Rio de Janeiro and the beginning of the austral autumn in Espírito Santo. These timings are not consistent with a strong northward movement of Subtropical Convergence (the encounter of a cold northward flow of Falkland/Malvinas current with a warmer southward flow of Brazil current), occurring primarily during the austral winter, and previously recognized as one of the main oceanographic features influencing the occurrence of P. spinipinnis in Brazilian waters (Molina-Schiller et al., Reference Molina-Schiller, Rosales and de Freitas2005). Given the rarity of these stranding events, this suggests a potential occurrence of P. spinipinnis further north in Brazilian waters.

While the influence of the Subtropical Convergence seems unlikely in our case, at least three other factors should be considered: (1) the species’ unobtrusive swimming behaviour and small group formation (Goodall et al., Reference Goodall, Norris, Harris, Oporto and Castello1995b; Santillán, Reference Santillán2022); (2) the South and Southeastern Brazilian continental shelf, which varies in width from 70 to 230 km offshore with depths of ⩽200 m (Mahiques et al., Reference Mahiques, Sousa, Furtado, Tessler, Toledo, Burone, Figueira, Klein, Martins and Alves2010); and (3) the presence of the nutrient-rich South Atlantic Central Waters (SACW) in mid- and outer continental shelf, along with its upwelling near the study area (Castelão and Barth, Reference Castelão and Barth2006). The former may suggest more challenging conditions for sightings by scientific expeditions, while the second supports the possibility of groups travelling further north within deeper waters of the continental shelf. Phocoena spinipinnis was already reported in waters up to 100 m in depth (Clay et al., Reference Clay, Mangel, Alfaro-Shigueto, Hodgson and Godley2018), resulting in decreased sighting probability due to limited scientific effort in offshore waters and rough sea conditions. The presence of nutrient-rich waters supports the occurrence of the species in a highly productive area. The water temperatures and salinities are below the representative values known to limit species’ geographical distribution in both the Pacific and Atlantic coasts (>24 °C and >36 psu, respectively) (Molina-Schiller et al., Reference Molina-Schiller, Rosales and de Freitas2005). In some areas of the South Brazilian Bight, including the Rio de Janeiro coast, SACW are characterized by cold waters (<20 °C) and salinities ranging from 35 to 36 psu (Stramma and England, Reference Stramma and England1999; Brandini et al., Reference Brandini, Nogueira, Simião, Codina and Noernberg2014; Castro, Reference Castro2014), comprising oceanographic features previously associated with P. spinipinnis occurrences (Goodall et al., Reference Goodall, Würsig, Würsig, Harris and Norris1995a; Molina-Schiller et al., Reference Molina-Schiller, Rosales and de Freitas2005; Reyes, Reference Reyes, Würsig, Thewissen and Kovacs2018).

Despite no evidence of bycatch being found, a fourth, albeit remote, possibility is that both specimens were taken as bycatch further south and subsequently dumped at sea. Despite these hypotheses, P. spinipinnis is extremely rare in Brazilian waters. Analyses of stranding data spanning over 30 years of effort in Southern Brazil reported only one specimen in the state of Santa Catarina and six in the state of Rio Grande do Sul (Prado et al., Reference Prado, Mattos, Silva and Secchi2016; Vianna et al., Reference Vianna, Loch, Castilho, Gaidzinski, Cremer and Simões-Lopes2016). The report from Vianna et al. (Reference Vianna, Loch, Castilho, Gaidzinski, Cremer and Simões-Lopes2016) is the same specimen reported by Simões-Lopes and Ximenez (Reference Simões-Lopes and Ximenez1989), making it the only record for Santa Catarina state to date. It is noteworthy that both studies describe systematic efforts within their local stranding monitoring programmes, thereby enhancing their chances of encountering dead mammals washed ashore and underscoring the rarity of the species and the robustness of the analysed data.

The information presented here results from systematic cetacean stranding monitoring, which involves continuing engagement with the public. Through this engagement, local residents and visitors actively contribute by reporting stranding occurrences to the scientific community enhancing the effectiveness of the monitoring programme. While these occurrences of P. spinipinnis may be considered extralimital, we report the first record in the state of Rio de Janeiro, Southeast Brazil, and provide new biological information on the species along its northernmost distributional range on the South American Atlantic border. Although no evidence of allopatric dispersion was investigated, the occurrence of pubescent and mature male individuals in such a distant location from southern Brazil is noteworthy. Finally, the continuation of these stranding monitoring efforts should enable further investigation into the species’ biological aspects in case of future occurrences.

Data

The data supporting the conclusions of this article are partially available at Sistema de Informação de Monitoramento da Biota Aquática under ID 508609, and Mayorga et al. (Reference Mayorga, Vanstreels, Bhering, Mamede, Costa, Pinheiro, Reis, Trazzi, Meirelles, Ribeiro and Siciliano2020) as listed in the References.

Acknowledgements

We gratefully acknowledge the logistical support provided by Universidade do Estado do Rio de Janeiro and the Faculdade de Oceanografia. We extend our thanks to the teams at MAQUA/UERJ and Instituto ORCA for their field and necropsy assistance during this study. Additionally, we express our appreciation to the residents of Saquarema and Parati beaches for their contributions in reporting the stranding of specimens in the states of Rio de Janeiro and Espírito Santo. The authors would also like to thank the two anonymous reviewers, as well as colleagues Lis Bittencourt, Nara Oliveira-Ferreria and Róisín Jordan, for their contributions to the final version of the manuscript. We also extend our gratitude to Associate Editor Dr Jenna Riekkola for her thoughtful comments and contributions to improving this manuscript. Carcasses were collected under licenses ABIO 755-2016 and SISBio 64724-11.

Author contributions

Rafael Ramos Carvalho: Conceptualization, data curation, formal analysis, investigation, methodology, resources, supervision, validation, visualization, writing – original draft, writing – review and edit. Joana Ikeda: Data curation, investigation, formal analysis, methodology, validation, writing – review and edit. Yasmin Daoualibi: Data curation, investigation, formal analysis, methodology, validation, writing – review and edit. Emi B. Guari: Data curation, investigation, formal analysis, methodology, validation, writing – review and edit. Pedro Teixeira: Data curation, investigation, formal analysis, methodology, validation, writing – review and edit. Elitieri B. Santos-Neto: Data curation, investigation, methodology, formal analysis, resources, validation, writing – review and edit. José Lailson-Brito: Funding acquisition, conceptualization, data curation, methodology, resources, supervision, validation, visualization, writing – review and edit. Lupercio Barbosa: Data curation, investigation, resources, supervision, validation, visualization, writing – review and editing. Marcelo Ramos-Nogueira: Data curation, investigation, resources, supervision, validation, visualization, writing – review and editing. Alexandre F. Azevedo: Funding acquisition, conceptualization, data curation, methodology, resources, supervision, validation, visualization, writing – review and edit.

Financial support

This work was supported by the Projeto de Monitoramento de Praias da Bacia de Santos e Espírito Santo (PMP-BS/PMP-ES). PMP is a monitoring program required by Instituto Brasileiro do Meio Ambiente dos Recursos Renováveis (IBAMA) and conducted by Petrobras. The work was also financed by Associação Cultural e de Pesquisa Noel Rosa. The Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) have supported research developed by MAQUA/UERJ. AA has research grants from CNPq (PQ-1B 307458/ 2022-9), FAPERJ (CNE E-26/200.397/2023) and UERJ (Prociencia), and JL-B has research grants from CNPq (PQ-1D 315.276/2021-5), and UERJ (Prociencia).

Competing interests

The authors declare no conflicts of interests.

References

Brandini, FP, Nogueira, M, Simião, M, Codina, JCU and Noernberg, MA (2014) Deep chlorophyll maximum and plankton community response to oceanic bottom intrusions on the continental shelf in the South Brazilian Bight. Continental Shelf Research 89, 6175. ISSN .CrossRefGoogle Scholar
Brownell, RL and Praderi, R (1984) Phocoena spinipinnis. Mammalian Species 217, 14.CrossRefGoogle Scholar
Burmeister, H (1865) Description of a new species of porpoise in the Museum of Buenos Aires. Proceedings of the Zoological Society of London 1865, 228231.CrossRefGoogle Scholar
Castelão, R and Barth, J (2006) Upwelling around Cabo Frio, Brazil: the importance of wind stress curl. Geophysical Research Letters 33, 25.CrossRefGoogle Scholar
Castro, BM (2014) Summer/winter stratification variability in the central part of the South Brazil Bight. Continental Shelf Research 89, 1523. https://doi.org/10.1016/j.csr.2013.12.002CrossRefGoogle Scholar
Clay, TA, Mangel, JC, Alfaro-Shigueto, J, Hodgson, DJ and Godley, BJ (2018) Distribution and habitat use of a cryptic small cetacean, the Burmeister's porpoise, monitored from a small-scale fishery platform. Frontiers in Marine Science 5, 220.CrossRefGoogle Scholar
Corcuera, J, Monzón, F, Crespo, EA, Aguilar, A and Raga, JA (1994) Interactions between marine mammals and coastal fisheries of Necochea and Claromeco (Buenos Aires province, Argentina). Report of The International Whaling Commission (Special Issue 15), 283290.Google Scholar
Corcuera, J, Monzon, F, Aguilar, A, Borrell, A and Raga, JA (1995) Life history data, organochlorine pollutants and parasites from eight Burmeister's porpoises, Phocoena spinipinnis, caught in northern Argentine waters. Report of The International Whaling Commission (Special Issue 16), 365372.Google Scholar
Galatius, A, Berta, A, Frandsen, MS and Goodall, N (2011) Interspecific variation of ontogeny and skull shape among porpoises (Phocoenidae). Journal of Morphology 272, 136148.CrossRefGoogle ScholarPubMed
Garcia-Godos, I, Van Waerebeek, K, Reyes, JC, Alfaro-Schigueto, J and Arias-Schreiber, M (2007) Prey occurrence in the stomach contents of four small cetacean species in Peru. Latin American Journal of Aquatic Mammals 6, 171183.CrossRefGoogle Scholar
Geraci, JR and Lounsbury, VJ (2005) Specimen and data collection. In Yates, NS (ed.), Marine Mammals Ashore: A Field Guide for Strandings, 2nd Edn. Baltimore, MD: National Aquarium in Baltimore, pp. 176194.Google Scholar
Goldin, PE and Vishnyakova, KA (2015) Differences in skull size of harbour porpoises, Phocoena phocoena (Cetacea), in the Sea of Azov and the Black Sea: evidence for different morphotypes and populations. Vestnik zoologii 49, 171180.CrossRefGoogle Scholar
Goodall, RNP, Würsig, B, Würsig, M, Harris, G and Norris, KS (1995a). Sightings of Burmeister's porpoise, Phocoena spinipinnis, off southern South America. Report of The International Whaling Commission (Special Issue 16), 297316.Google Scholar
Goodall, RNP, Norris, KS, Harris, G, Oporto, JA and Castello, HP (1995b). Notes on the biology of Burmeister's porpoise Phocoena spinipinnis off southern South America. Report of The International Whaling Commission (Special Issue 16), 347.Google Scholar
Guerra-Correa, C, Van Waerebeek, K, Kandora, GP and Jorquera, GL (1987) The presence of cetaceans off northern Chilean coast. Estudios Oceanológicos 6, 8796.Google Scholar
Hohn, A, Scott, M, Wells, R, Sweeny, JS and Irvine, AB (1989) Growth layers in teeth from known-age, free-ranging bottlenose dolphins. Marine Mammal Science 5, 315342.CrossRefGoogle Scholar
Mahiques, MM, Sousa, SHM, Furtado, VV, Tessler, MG, Toledo, FAL, Burone, L, Figueira, RCL, Klein, DA, Martins, CC and Alves, DPV (2010) The Southern Brazilian shelf: general characteristics, quaternary evolution and sediment distribution. Brazilian Journal of Oceanography 58, 2534.CrossRefGoogle Scholar
Marchesi, MC, Galatius, A, Zaffino, M, Coscarella, MA and González-José, R (2022) Vertebral morphology in extant porpoises: radiation and functional implications. Journal of Morphology 283, 273286.CrossRefGoogle ScholarPubMed
Mayorga, LFSP, Vanstreels, RET, Bhering, RCC, Mamede, N, Costa, LMB, Pinheiro, FCF, Reis, LWD, Trazzi, A, Meirelles, WLCM, Ribeiro, AM and Siciliano, S (2020) Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975–2015. ZooKeys 948, 129152.CrossRefGoogle Scholar
Molina-Schiller, DMM (2006) Variação geográfica do Boto-de-Burmeister (Burmeister, 1865) (Cetacea: Phocoenidae) nas costas Atlântica e Pacífica da América do Sul (PhD. thesis). Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil.Google Scholar
Molina-Schiller, DM, Rosales, SA and de Freitas, TRO (2005) Oceanographic conditions off coastal South America in relation to the distribution of Burmeister's porpoise, Phocoena spinipinnis. Latin American Journal of Aquatic Mammals 4, 141156.CrossRefGoogle Scholar
Padula, AD, Machado, R, Milmann, L, de León, MC, Gana, JCM, Wickert, JC, Argañaraz, ME, Bastida, RB, Rodríguez, DH and Denuncio, PE (2023) Marine debris ingestion by odontocete species from the Southwest Atlantic Ocean: absence also matter. Marine Pollution Bulletin 186, 114486.CrossRefGoogle Scholar
Perrin, WF (1975) Variation of spotted and spinner porpoise (genus Stenella) in the Eastern Pacific and Hawaii. Bulletin of the Scripps Institution of Oceanography 21, 1206.Google Scholar
Perrin, WF and Myrick, AC (1980) Age determination of toothed whales and sirenians. Reports of the International Whaling Commission (Special Issue 3), 229 pp.Google Scholar
Petrobras. (2023) Projeto de Monitoramento de Praias da Bacia de Santos (PMP-BS). Available at https://comunicabaciadesantos.petrobras.com.br/projeto-de-monitoramento-de-praias-pmp-. Accessed 05 December 2023.Google Scholar
Pinedo, MC (1989) Primeiro registro de Phocoena spinipinnis (Cetacea, Phocoenidae) para o litoral do Rio Grande do Sul, Brasil, com medidas osteologicas e análise do conteúdo estomacal. Atlantica 11, 8599.Google Scholar
Prado, JHF, Mattos, PH, Silva, KG and Secchi, ER (2016) Long-Term seasonal and interannual patterns of marine mammal strandings in subtropical Western South Atlantic. PLoS ONE 11, e0146339.CrossRefGoogle ScholarPubMed
Reyes, JC (2018) Burmeister's porpoise: Phocoena spinipinnis Burmeister, 1865. In Würsig, B, Thewissen, JGM and Kovacs, KM (eds), Encyclopedia of Marine Mammals, 3rd Edn. Academic Press, 4 pp. ISBN 9780128043271. https://doi.org/10.1016/B978-0-12-804327-1.00022-4Google Scholar
Reyes, JC and Van Waerebeek, K (1995) Aspects of the biology of Burmeister's porpoise from Peru. Reports of the International Whaling Commission (Special Issue 16), 349364.Google Scholar
Rosa, S, Milinkovitch, MC, Van Waerebeek, K, Berck, J, Oporto, JA, Alfaro-Shigueto, J, Van Bressem, MF, Goodall, R and Cassens, I (2005) Population structure of nuclear and mitochondrial DNA variation among south American Burmeister's porpoises (Phocoena spinipinnis). Conservation Genetics 6, 431443.CrossRefGoogle Scholar
Santillán, L (2022) Observations of Burmeister's porpoise (Phocoena spinipinnis) in the Northern Coast of Peru. Aquatic Mammals 48, 266272.CrossRefGoogle Scholar
Simões-Lopes, PC and Ximenez, A (1989) Phocoena spinipinnis Burmeister 1865, na costa sul do Brasil (Cetacea-Phocoenidae). Biotemas 2, 8389.Google Scholar
Stramma, L and England, M (1999) On the water masses and mean circulation of the South Atlantic Ocean. Journal of Geophysical Research 104, 20,86320,883.CrossRefGoogle Scholar
Van Waerebeek, K, Santillan, L and Reyes, JC (2002) An unusually large aggregation of Burmeister's porpoise Phocoena spinipinnis off Peru, with a review of sightings from the Eastern South Pacific. Noticiario Mensual 350, 1217.Google Scholar
Vega, D, Van Waerebeek, K, Alfaro-Shigueto, J, Reyes, JC and Van Bressem, M (2022) Macroscopic and histological descriptive gonadal study in different stages of sexual maturity of the Burmeister's porpoise Phocoena spinipinnis from Peru. Preprints, 2022090020. https://doi.org/10.20944/preprints202209.0020.v1Google Scholar
Vianna, TS, Loch, C, Castilho, PV, Gaidzinski, MC, Cremer, MJ and Simões-Lopes, PC (2016) Review of thirty-two years of toothed whale strandings in Santa Catarina, southern Brazil (Cetacea: Odontoceti). Zoologia (Curitiba) 33, e20160089. https://doi.org/10.1590/s1984-4689zool-20160089CrossRefGoogle Scholar
Weir, CR and Rutherford, S (2019) First record of Burmeister's porpoise (Phocoena spinipinnis) in the Falkland Islands (Malvinas). Marine Biodiversity Records 12, 19.CrossRefGoogle Scholar
Figure 0

Figure 1. Previously known northernmost range of Phocoena spinipinnis in the Southwestern Atlantic Ocean (SWAO) in Santa Catarina state (SC) (black dot), new occurrence reported in this paper (red star) in Rio de Janeiro state (RJ) 930 km northward, and the occurrence reported in Mayorga et al. (2020) in Espírito Santo State (ES) (black star). The monitoring areas for PMP-BS and Instituto Orca are represented by coastal orange and red polygons, respectively.

Figure 1

Figure 2. Stranded Burmeister's porpoise, Phocoena spinipinnis, in the states of Rio de Janeiro (A–C) and Espírito Santo (D), southeastern Brazil. (A) Head with partially macerated left jaw, ventral laceration by suggestive post-mortem shark bites, presence of teeth and absence of the left eye; (B) Suggestive post-mortem shark bites on umbilicus/thoracic cavity and genital slit; (C) Low, triangular-shaped canted backward dorsal fin; (D) Specimen found stranded in Praia de Parati, Anchieta, Espírito Santo.

Figure 2

Figure 3. Specimen of Burmeister's porpoise, Phocoena spinipinnis, stranded in the state of Rio de Janeiro, southeastern Brazil in April 2021, during necropsy (A) and evidence of penis (B) and teeth (C).

Figure 3

Figure 4. Vertebral structure of a Burmeister's porpoise, Phocoena spinipinnis, stranded in the state of Rio de Janeiro, southeastern Brazil in April 2021. Cv – cervical; Th – thoracic; Lb – lumbar and Cd – caudal. Scale bars: 5 cm.

Figure 4

Table 1. Skull measurements (mm) of a Burmeister's porpoise (Phocoena spinipinnis) specimen stranded in Praia da Vila, Saquarema, Rio de Janeiro, southeastern Brazil in April, 2021

Figure 5

Figure 5. Dorsal, ventral, and lateral view of the skull, and inner and outer side of the left mandible of a Burmeister's porpoise, Phocoena spinipinnis, stranded in the state of Rio de Janeiro, southeastern Brazil, in April 2021. Scale bars: 5 cm.