Life-history of the spiny butterfly ray, Gymnura altavela (Chondrichthyes: Myliobatiformes), kept under human care in a marine aquarium Clara V. Teixeira‐Leite, Francisco Marcante Santana, Rafael Franco Valle, Veronica Takasuka, Matheus Felix de Góes, et al. Journal of Fish Biology, 2024 The Rio de Janeiro Marine Aquarium (AquaRio) is the first to successfully maintain and reproduce the spiny butterfly ray (Gymnura altavela), providing unique information about the species' biology. Seven rays were kept in captivity between 2018 and 2023, two captured on the southeastern coast of Brazil and five born in the aquarium. The applied abiotic conditions and nutrition allowed for the survival, growth, and reproduction of these individuals. Growth parameters (asymptotic disk width—DW∞ and growth coefficient—k) were estimated based on the von Bertalanffy model using the Fabens method for males and females separately. The best models estimated DW∞ = 106.47 cm and k = 0.396 for males and DW∞ = 172.2 cm and k = 0.190 for females. Sexual dimorphism was corroborated, with females reaching larger sizes and presenting slower growth rates than males. The estimated k values were higher than those estimated for rays of similar size to G. altavela in the natural environment, probably due to the constant water temperature (around 25.5°C), food abundance, low population density, reduced predation rates, and high water quality in the captive environment. A comparison of the captivity findings with other studies on G. altavela age and growth in the Atlantic and Mediterranean indicates a broad phenotypic plasticity regarding growth. Three G. altavela reproductions were recorded, with size at birth appearing to be a key factor for pup's survival. Behavioral pattern observations associated with reproduction are also described, encompassing chasing and copulation, whereas the species’ internal morphology is described through coelomic cavity ultrasound scanning.
Effects of fishing on the Serra Spanish Mackerel (Scomberomorus brasiliensis) in Northeast Brazil Amanda Graziele Araújo Resende, Fabrice Duponchelle, Francisco Marcante Santana, Rosângela Paula Lessa Fisheries Management and Ecology, 2024 The Spanish mackerel (Scomberomorus brasiliensis) is of high commercial value throughout its distribution. In Northeast Brazil, this important fishery resource has been under strong fishing pressure since the 1960s, with length composition changing between 1998–2001 and 2020–2022. Length frequency distributions, exploitation indicators, and gear selectivity indicated the effects of overfishing on stock size structure, with excessive withdrawal of spawners and reduced numbers of adults larger than 60 cm in catches. In addition, gear selectivity changed, with reduced size at first capture in the 40‐mm mesh. Our results indicated that the species is unsustainably exploited in the study area and suggested both growth and recruitment overfishing.
Age and Growth of the Threatened Smalleye Round Ray, Urotrygon microphthalmum, Delsman, 1941, from Northeastern Brazil Jones Santander-Neto, Francisco Marcante Santana, Jonas Eloi Vasconcelos-Filho, Rosângela Lessa Fishes, 2023 The age and growth of Urotrygon microphthalmum were studied using specimens captured between March 2010 and March 2012 as by-catch in the shrimp trawl fishery off the coast of the state of Pernambuco, Brazil. A total of 347 vertebrae were read, 161 from males (81.6–249.55 mm) and 186 from females (86.15–298.1 mm). The estimated average percentage index (IAPE) ranged from 0.71% to 4.33% (mean = 2.5%) in vertebrae from specimens with 1 and 6 band pairs, respectively. In the present study, the different approaches to validation produced variable results (partially valid growth zones). We then decided to discuss the growth of the species considering the formation of an annual ring. There were statistically significant differences in growth between the sexes. The best model to describe male growth was the von Bertalanffy growth model for two phases (VBGM TP) with growth parameters L∞ (maximum theoretical length) = 230.35 mm, k (growth constant) = 1.00, t0 (theoretical age of size zero) = −0.76 years and for females it was the von Bertalanffy with birth size (VBGM L0) model with parameters L∞ = 282.55 mm, k = 0.37. The age of maturity for males and females was 1.52 and 2.02 years, respectively, and the maximum age observed was 5.5 and 8.5 years, respectively. Despite being a fast-growing species, Urotrygon microphthalmum is threatened, probably due to the high mortality levels from shrimp trawling in a very narrow range of the shelf where all the life stages are captured.
Age and growth of the Brazilian sharpnose shark, Rhizoprionodon lalandii and Caribbean sharpnose shark, R. porosus (Elasmobranchii, carcharhinidae) on the northern coast of Brazil (Maranhão) Pan American Journal of Aquatic Sciences, 2009
