Abstract
Abstract The present work aimed at studying the sicklefin devil ray (Mobula tarapacana) that aggregates seasonally in the Saint Peter and Saint Paul Archipelago (SPSPA). From December 2008 to June 2016, 827 rays were sighted through free diving visual census survey. From the total of the records, it was possible to identify the sex of 361 specimens, in which 215 were females and 146 were males. The disk width ranged from 2.40 m to 3.20 m with mean size of 2.60 m, for both males and females, indicating that the population is composed by sub-adults and adults. Using photo-identification of the pectoral-fins in the ventral side, 11 males and 44 females were identified and compared with each other, but no re-sight was detected. Recent mating scars were observed in males (n= 7) and females (n= 6), as well as courtship and pursuit behaviors, confirming that the SPSPA is an important area of aggregation and mating for M. tarapacana in the Atlantic Ocean.
Highlights
A significant increase in catches of Mobulids worldwide due to the growing consumption of gill plates in the Asian market prompted population declines in recent years (Heinrichs et al, 2011; Couturier et al, 2012; Croll et al, 2016; O’Malley et al, 2017)
The present study suggests that M. tarapacana is using the archipelago as a mating ground, due to the evidences of courtship behavior and of potentially recent mating marks and scars showed
Other species of elasmobranches use the area during part of their reproductive cycle, such as M. thurstoni (Mendonça et al, 2012; McCallister et al, 2020), the silky shark (Hazin et al, 2007), and the whale shark (Macena, Hazin, 2016)
Summary
A significant increase in catches of Mobulids worldwide due to the growing consumption of gill plates in the Asian market prompted population declines in recent years (Heinrichs et al, 2011; Couturier et al, 2012; Croll et al, 2016; O’Malley et al, 2017). The sicklefin devil ray is morphologically characterized by having the pelvic region longer and the spiracle longitudinally elongated (Notarbartolo-di-Sciara, 1988) They have a long head and reduced cephalic fins; a short tail, dorsal coloration ranging from dark brown to olive green and the ventral side white, with a grey posterior border and an irregular but well-marked demarcation line (Notarbartolodi-Sciara, 1987). Due to its mainly oceanic habit and migratory behavior, travelling great distances in few months (Thorrold et al, 2014), studies about its population dynamics and ecology are difficult and, still scarce. Such a migratory behavior adds complexity to the planning of spatial management of the species, given the capacity to cross geopolitical borders
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