Reproductive biology of the guitarfish Rhinobatos percellens (Chondrichthyes, Rhinobatidae) from the São Paulo Coast, Brazil, western South Atlantic Ocean

Abstract

The reproductive biology of the guitarfish Rhinobatos percellens was studied from 751 specimens caught by bottom pair trawlers off the coast of São Paulo, Brazil, between c. 24° 00' S; 45° 15' W and c. 25° 10' S; 47° 52' W, from September 2007 to August 2009. The total length (L(T)) and total mass (M(T)) relationship for males and females combined was M(T) = 1·29E-06 L(T) (3·15) (r = 0·99, n = 751). The mean L(T) of sexually mature specimens was 548 mm for males and 583 mm for females. Clasper growth was allometric and showed three distinct phases. Most claspers were calcified in specimens of c. 550 mm L(T). The mean diameter of the largest oocyte was 29·8 mm, the mean ovarian fecundity was seven oocytes and ovulation occurred between August and November. Uterine fecundity ranged from two to 13 embryos (mean of five embryos). Larger females had higher litter sizes and larger embryos; the size-at-birth was c. 200 mm L(T). The hepato-somatic index oscillated seasonally for males and females; the gonado-somatic index had little variation in males, but varied seasonally in females. The presence of many non-pregnant adult females and of encapsulated eggs during two consecutive seasons suggests a resting period between gestations and the possibility of diapause.

Notes on the reproductive biology of the Brazilian electric ray Narcine brasiliensis (Elasmobranchii: Narcinidae)

“…() for N . bancroftii , and by Rocha & Gadig () for Chola guitarfish Rhinobatos percellens (Walbaum 1792). Such results may also be a reflection of the low number of specimens available during this study or the lack of smaller size classes in the present sample.…”

Age and growth of three endemic threatened guitarfishes Pseudobatos horkelii, P. percellens and Zapteryx brevirostris in the western South Atlantic Ocean

“…Despite the occurrence and distribution of these species along the south‐east to south coast of Brazil, most of the few studies undertaken to date have focused on reproduction (Abilhoa et al ., ; Batista, ; Colonello et al ., ; Lessa et al ., ; Martins et al ., ; Rocha & Gadig, ) and feeding habits (Bornatowski et al ., ; Carmo et al ., ; Marion et al ., ). The knowledge of other aspects of their basic biology, including age and growth parameters, is fairly limited and only available for P. horkelii and Z. brevirostris in southern Brazil (Carmo et al ., ; Lessa, ; Vooren et al ., ) and for P. Percellens in north‐eastern Brazil (Nunes, ).…”

“…Despite the occurrence and distribution of these species along the south-east to south coast of Brazil, most of the few studies undertaken to date have focused on reproduction (Abilhoa et al, 2007;Batista, 1991;Colonello et al, 2011;Lessa et al, 1986;Martins et al, 2018;Rocha & Gadig, 2012) and feeding habits (Bornatowski et al, 2010;Carmo et al, 2015;Marion et al, 2011).…”

Reproductive biology of the Brazilian guitarfish, Pseudobatos horkelii (Müller & Henle, 1841) from southeastern Brazil, western South Atlantic

“…() observed a slightly smaller size in southern Brazil (129 cm for males, 135 cm for females). Differences in length among the geographic distribution were observed in other species such as P. percellens in southeastern Brazil (Rocha & Gadig, ) and Colombia (Grijalba‐Bendeck, Acero, & Gonzalez, ); and for the skate Atlantoraja castelnaui in southeastern Brazil (Oddone & Amorim, ) and Uruguay (Orlando, Pereyra, Paesch, & Norbis, ). Such differences may occur due to methodological variations, such as gear selectivity.…”

“…Brazil (129 cm for males, 135 cm for females). Differences in length among the geographic distribution were observed in other species such as P. percellens in southeastern Brazil (Rocha & Gadig, 2013) and Colombia (Grijalba-Bendeck, Acero, & Gonzalez, 2008); and for the skate Atlantoraja castelnaui in southeastern Brazil and Uruguay ( (Ebert, Compagno, & Cowley, 2008), possibly related to water temperature and latitude differences (Yamaguchi, Taniuchi, & Shimizu, 2000), could explain these intra-specific length variations.…”