Background. In fishery biology, information on life-history traits is extremely useful for species conservation and the monitoring, management and sustaining of fish stocks. Nevertheless, detailed biological information is very limited for tropical fishes, especially for those with low economic value, such as the Atlantic bumper, Chloroscombrus chrysurus (Linnaeus, 1766). This species is commonly captured by artisanal fisheries in tropical waters and the lack of information makes difficult the development of strategies for the proper management of the species. Therefore, the presently reported study intended to provide new data on the biological parameters of C. chrysurus to fill the gap in the existing knowledge. Materials and methods. Life-history traits of the Atlantic bumper, C. chrysurus, were estimated from 335 fish collected in a western Atlantic region during fishery surveys carried out between 2010 and 2012. Age and growth were determined by annuli counts of sagittal otoliths. Growth parameters were calculated by adjusting the backcalculated length-per-age to the von Bertalanffy growth model. Empirical equations and data on maturity were used to estimate the size and age at first maturity, as well as the optimum size and age. Theoretical longevity and natural mortality were also estimated for the species. Results. Six age classes were identified and asymptotic length (L ∞ ), growth rate (k), and the theoretical age when the specimen was at zero length (t 0 ) for the whole population assumed the following values: L ∞ = 25.49 cm, k = 0.32 year -1 , and t 0 = 0.058 years. No evidence of sexual size dimorphism was found, with no significant differences in growth characteristics and in the length frequency distribution between sexes. The principal vital parameters were as follows: size (L 50 = 15.5 cm) and age (T 50 = 2.9+) at sexual maturity, optimum length (L opt = 13.08 cm), and optimum age (T opt = 2.1+), as well as its theoretical longevity (A 0.95 = 9.17) and natural mortality (M = 0.92). Conclusion. The determined size and age at sexual maturity, optimum length and age, theoretical longevity, and natural mortality indicate that the studied population of C. chrysurus is overexploited. The Atlantic bumper is vulnerable to fishing pressure and should be managed with caution.
Pelagic elasmobranchs are key elements of oceanic ecosystems and must be preserved if marine trophic networks are to be kept in balance. Yet, they face intense fishing pressure that has been threatening their populations worldwide. Ensuring proper conservation management of these taxa depends on a better understanding of the strategies they use to explore the pelagic realm and their contributions to trophic web structuring across the ocean column. This study aimed at examining relationships between vertical habitat use and trophic attributes among six sympatric pelagic elasmobranchs using satellite transmitting tags in the western equatorial South Atlantic Ocean. The vertical movements of 35 elasmobranch individuals were tracked during an overall total of 1911 days. Clear relationships between species’ feeding habits, maximum diving depths, and proportion of time spent either in epipelagic or in surface waters were evidenced by Bayesian generalized linear mixed models and multivariate analysis. Filter-feeders made most use of deep waters from the mesopelagic and bathypelagic and shifted their diving depths in phase with diel vertical migrations of the deep scattering layer, i.e., shallower during the night and deeper during the day. Specialists exhibited distinct diving patterns in epipelagic and mesopelagic waters across the diel period which are potentially indicative of habitat partitioning, whereas generalists were more surface-oriented but also explored deeper waters compared to specialists. The trophic level also seemed to influence elasmobranch maximum diving depths, which tended to become shallower as species’ trophic level increased. These results corroborate previous evidence of widespread vertical habitat partitioning among sympatric pelagic predators and depict a trophic-mediated structuring of the pelagic environment where top-down control may be exerted at different depths by distinct species. Further research is yet required to understand the role of elasmobranch vertical movements in structuring pelagic habitats as well as to guide ecosystem-based fisheries management aimed at reducing species susceptibility to fishing gear and at preserving the structure and functionality of marine trophic networks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.