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Round rays (family: Urotrygonidae) are commonly caught as by-catch by shrimp trawl fisheries in the tropical eastern Pacific (TEP). However, little information on their life history and catch species composition exists for most round ray species, preventing the evaluation of the impact of fishing on their populations. The mean size at sexual maturity (DW 50 ), seasonal variation by maturity stages, and fecundity for two round ray species caught during shrimp trawl research cruises in the south-eastern Gulf of California (northern TEP) were estimated using a multi-model approach and inference for the first time, to determine the part of the population of each species that is being affected by shrimp trawling. Disc width (DW) ranged from 7.0 to 30.9 cm for the spotted round ray (Urobatis maculatus), and 7.2-33.5 cm for the thorny stingray (Urotrygon rogersi), with females reaching larger sizes than males in both species. The DW 50 was estimated at 12.8 and 11.8 cm DW for the males and females of U. maculatus, respectively, whereas for U.rogersi, it was 15.0 and 18.4 cm DW for males and females, respectively. Embryos were found in females ≥14.5 cm DW in both species. The maximum fecundity was five embryos for U. maculatus (mean = 3.1 ± 0.2 S.E., mode = 4), and six embryos for U. rogersi (mean = 3.0 ± 0.3 S.E., mode = 2). Fecundity and embryo size did not vary with maternal size. Male and female immature and mature individuals for both species, including pregnant females, were found in the catches in all seasons of the year. Our results can help determine the vulnerability of the studied species populations to fishing pressure from shrimp trawling in the northern TEP and guide the development of future monitoring strategies and conservation actions for these species, if necessary., (© 2024 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.)

The Peruvian sea represents one of the most productive ocean ecosystems and possesses one of the largest elasmobranch fisheries in the Pacific Ocean. Ecosystem-based management of these fisheries will require information on the trophic ecology of elasmobranchs. This study aimed to understand the diet, trophic interactions and the role of nine commercial elasmobranch species in northern Peru through the analysis of stomach contents. A total of 865 non-empty stomachs were analysed. Off northern Peru, elasmobranchs function as upper-trophic-level species consuming 78 prey items, predominantly teleosts and cephalopods. Two distinctive trophic assemblages were identified: (a) sharks (smooth hammerhead shark Sphyrna zygaena, thresher shark Alopias spp. and blue shark Prionace glauca) that feed mainly on cephalopods in the pelagic ecosystem; and (b) sharks and batoids (Chilean eagle ray Myliobatis chilensis, humpback smooth-hound Mustelus whitneyi, spotted houndshark Triakis maculata, Pacific guitarfish Pseudobatos planiceps, copper shark Carcharhinus brachyurus and school shark Galeorhinus galeus) that feed mainly on teleosts and invertebrates in the benthonic and pelagic coastal ecosystem. This study reveals for the first time the diet of T. maculata and the importance of elasmobranchs as predators of abundant and commercial species (i.e., jumbo squid Dosidicus gigas and Peruvian anchovy Engraulis ringens). The results of this study can assist in the design of an ecosystem-based management for the northern Peruvian sea and the conservation of these highly exploited, threatened or poorly understood group of predators in one of the most productive marine ecosystems., (© 2020 Fisheries Society of the British Isles.)