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Copyright of Revista de Biologia Marina y Oceanografía (RBMO) is the property of Universidad de Valparaiso, Facultad de Ciencias del Mar and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study found that the reef stingray Urobatis concentricus presents a matrotrophic aplacental viviparous reproduction with yolk sac and trophonemata formation. Growth of ovarian follicles occurs asynchronously and continuously with fecundity of three embryos per female. A maximum size of 58·4 cm total length and 37·6 cm disc width was recorded, corresponding to a mature female of 3 or 4 years of age. [ABSTRACT FROM AUTHOR]

Until March 2021, marine Chondrichthyans in Colombia were fishery resources, administered under the Ministry of Agriculture (MinAgricultura) with the fisheries authority had an NPOA Sharks as a guide for their management. After that, and under the Decree 281 of 18 March 2021 issued by the Ministry of Environment of Colombia, a new policy (called the Environmental Plan for the protection and conservation of sharks, marine rays, and chimaeras of Colombia)emerged, and the management duty of Chondrichthyans changed from a fishery resource to a hydrobiological resource, thereby prohibiting commercial use of those species and transferring its management to the government's environmental sector. This paper discusses the two policy instruments created for the same group of fishes, the consequences of changing the government management duty from one sector to another by the new policy created, and the implications for the environmental, fisheries, control, and surveillance sectors, civil organizations, and even for sharks. In addition, a logical framework analysis method was carried out to identify shark vulnerability and stakeholders, and to analyze both policy instruments and their positive and negative outputs. Part of the environmental sector celebrated the issued decree as an unprecedented achievement for Colombia. In contrast, other stakeholders, including the fisheries sector, declared that the ban on sharks/batoids for trade and fishing indirectly affects marine fisheries and fishers since these species are commonly bycatch in most of them. Consequently, shark/batoid bycatch management was raised as the central management issue since fishing activity is the main threat for elasmobranchs. Alternatives are proposed for conservation and fisheries to coexist, obtaining mutual benefits, avoiding confrontation, and heading towards sustainable development from different perspectives. • Sharks/batoids are vulnerable to fishing and other pressures due to life-history traits. • Shark/batoids are bycatch in most Colombian marine fishing gear/methods at all scales. • Governmental conservation decree of 2021 establishes sharks/batoids protection/conservation measures in Colombia. • A comparison of two policy instruments was carried out. • Government and civil society implications raised regarding recent sharks/batoids conservation measures. [ABSTRACT FROM AUTHOR]

This study evaluated the relationship between body size and geographic range size, measured as extent and volume of occurrence of resident and endemic elasmobranchs of the Tropical Eastern Pacific. Data of body size, minimum and maximum depths, and latitudinal distribution of the species were obtained from the literature. Extent and volume of occurrence were measured from 3080.25-km² quadrants, considering the northern and southern boundaries, the maximum depth, and the depth interval of the 82 species included. The relationships between body size and depth, extent of occurrence, and volume of occurrence, and between body size and bathymetric zones were evaluated using linear regression and a nonparametric analysis of variance, respectively. The relationship between body size and extent of occurrence was positive for all groups and significant only for the batoids. They occupy smaller depth intervals than sharks and are almost exclusively restricted to the euphotic zone; the resident sharks occur in the three bathymetric zones, but not the endemic sharks. The interspecific relationship of body size and volume of occurrence revealed a triangle with defined boundaries, with 22 species under the constraint line (13 sharks and 9 batoids), Pristis sp. and Manta birostris being the most prone to extinction. Although there were no factors or characteristics common to all 22 species, variables such as habits and reproductive traits influence their vulnerability, in addition to the human pressures to which they are subjected. In elasmobranchs, the triangular relationship between body size and range size is a good predictor of species susceptible to extinction, which is useful for assessing the threat status and taking action for management and prioritization of species at regional level. [ABSTRACT FROM AUTHOR]

Hematological and blood biochemical reference information is important to establish physiological status of freshwater stingray populations and improve care and management protocols in artificial environments. Here, we used a commercial freshwater stingray with high mortality rates in the market (Potamotrygon magdalenae), as an example to understand how artificial environments and handling protocols influence physiological status of captive freshwater stingrays. To this purpose, blood from five adult males and six adult females was collected to perform complete blood counts and blood chemistry analyses. All sampled animals showed good body condition with no differences between sexes. Differences between sexes were only found for the differential count of lymphocytes. Red blood results were consistent with previously studied potamotrygonids while white blood results showed higher values of leukocytes, thrombocytes, heterophils and lymphocytes in P. magdalenae compared to other Potamotrygonids. All types of leukocytes described for elasmobranchs were found except neutrophils and basophils. Blood metabolites showed an influence of ex situ diet in total protein, triglycerides and cholesterol. Glucose results were consistent while urea showed lower levels than those recorded for other freshwater stingrays. These results highlight the importance of physical, physiological and health analysis in freshwater stingrays as a part of welfare assessment to improve monitoring protocols and survival rates in public or private aquaria.