Artisanally Landed Elasmobranchs Along the Coast of Rio De Janeiro, Brazil

Abstract

Considering the knowledge gap regarding elasmobranch species landings, this study aimed to report elasmobranch catches from artisanal fisheries to obtain baseline data in this regard. Samplings were carried out from 2016 to 2019 at three artisanal fishing colonies located in Rio de Janeiro, Tamoios, in Cabo Frio, Itaipu, in Niterói, and Copacabana, in the metropolitan rgeion of Rio de Janeiro, A trust relationship was built with the fishers, enabling ample data collection. A total of twenty-two species from twelve families were identified at all sample sites, comprising 10 sharks and 12 rays. Although Tamoios, in Cabo Frio, is home to an upwelling phenomenon, the highest richness concerning oceanic elasmobranchs was observed at Copacabana,, which is a part of Guanabara Bay, reinforcing the significant biodiversity of this bay and the importance of its recovery for elasmobranch management and conservation strategies. In addition, many specimens belonging to different species sampled at this site were juvenile, while three spinner shark females (Carcharinus brevipinna) with mature oocytes were also noted (indicating a possible strategic reproduction and juvenile settlement site for several of the landed species. The presence of many species presenting different vulnerability degrees regarding conservation and endemism, especially for the South Atlantic, reinforces the importance of this type of assessment. In addition, four keystone elasmobranch species previously observed throughout the Southeastern coast of Brazil are reported herein, , further indicating the importance of future assessments concerning elasmobranch fisheries monitoring in Brazil. In addition, artisanal fishing colonies may also act as research collaborators, as they display the potential to enable fishing strategies that allow the population, including researchers, to access a considerable portion of the elasmobranch diversity present throughout the coast of Rio de Janeiro. ResumoConsiderando a lacuna de conhecimento em relação aos desembarques de espécies de elasmobrânquios, este estudo teve como objetivo relatar as capturas de elasmobrânquios através da pesca artesanal para obter dados de base a esse respeito. As amostragens foram realizadas de 2016 a 2019 em três colônias depesca artesanal localizadas no Rio de Janeiro, Tamoios, em Cabo Frio, Itaipu, em Niterói e Copacabana, na região metropolitana do Rio de Janeiro. Um total de vinte e três espé cies de doze famílias foi identifi cado em todos os locais da amostra, incluindo 10 tubarões e 12 raias. Embora Tamoios, emCabo Frio, sofra os efeitos de um fenômeno de ressurgência, a maior riqueza relativa a elasmobrânquios oceânicas foi observada em Copacabana, que faz parte da Baía de Guanabara, reforçando a biodiversidade signifi cativa dessa baía e a importância de sua recuperação para estratégias de manejo e conservação de elasmobrânquios. Além disso, muitos espécimes pertencentes a diferentes espécies amostradas neste local eram juvenis, como tubarões martelo (Sphyrna lewini), tigre (Galeocerdo cuvier), mako Isurus oxyrinchus), seis fêmeas de cações frango (Rhizoprionodon lalandii) contendo embriões ou oocitos e três fêmeas de tubarão-rotador (Carcharinus brevipinna) com oócitos maduros, indicando um possível local estratégico de reprodução e assentamento juvenil para várias espécies desembarcadas. A presença de muitas espécies apresentando diferentes graus de vulnerabilidade em relação à conservação e endemismo, especialmente para o Atlântico Sul, reforça a importância desse tipo de avaliação. Além disso, quatro de seis espécies-chave de elasmobrânquios, ou seja, espécies que apresentam um impacto extremamente alto em um ecossistema específi co em relação à sua população e críticas para a estrutura e função gerais de um ecossistema, anteriormente observadas na costa sudeste do Brasil, são relatadas aqui, a saber Galeocerdo cuvier, Sphyrna lewini, S. zygaena e Zapteryx brevirostris, indicando ainda a importância de futuras avaliações sobre o monitoramento da pesca de elasmobrânquias no Brasil.Palavras-chave: Biodiversidade; Tubarões e raias; Pesca artesanal.

New Occurrences of the Tiger Shark (Galeocerdo cuvier) (Carcharhinidae) off the Coast of Rio de Janeiro, Southeastern Brazil: Seasonality Indications

“…Four additional records for the city of Rio de Janeiro were obtained from scientific articles by [ 16 , 22 ]. At least six abstracts presented between 1993 and 2018 at scientific events were identified (i.e., Oceanography Weekland Meetings of the Brazilian Society for the Study of Elasmobranchs, among others) mentioning the presence of the species on the coast of Rio de Janeiro, but we did not analyze these data in compliance with journal rules.…”

“…More recently, four new records for the northern Rio de Janeiro coast were recovered from local fisher knowledge from the last 50 years [ 35 ]. Only Araujo et al [ 16 ] presented detailed records of two individuals captured in 2018 and 2019 on Copacabana beach by the Z13 colony, in the metropolitan region of Rio de Janeiro. Although the tiger shark has been reported as among the least abundant shark species on the coast of different Brazilian states, including Rio de Janeiro, we believe that the number of tiger shark records may be higher than the records obtained herein, as we analyzed data from the last 40 years for only about 7% of the 28 colonies and fisher associations in the state.…”

“…In general, the tiger shark is among the least abundant shark species along the coast of different Brazilian states, such as Recife, Pernambuco [ 15 ], Rio de Janeiro itself [ 16 ], and near Mel Island in the state of Paraná [ 17 ]. This is possibly due to tiger sharks not being the main object of fishing unlike other shark species.…”

“…Currently, one-third of Brazilian shark species are threatened [ 14 ], although the true status of many species is unknown due to lack of information [ 13 ]. This is true for the tiger shark Galeocerdo cuvier (Péron & Lesueur, 1822) (Carcharhinidae), which, although one of the least representative species in northeast [ 15 ], southeast [ 16 ], and south [ 17 ] Brazil, has been classified as near threatened along the Brazilian coast, in line with its global categorization [ 14 , 18 ]. Australia has, in fact, recently identified declines in this species abundance [ 19 ].…”

“…Among the several shark species caught by artisanal fisher colonies in Rio de Janeiro, the tiger shark has always been one of the least recorded [ 16 , 22 , 23 ]. The tiger shark is a large iconic predator that can reach 500 cm in length and weigh around 900 kg [ 24 ].…”