Globally, ecosystems have suffered from anthropogenic stressors as we enter the sixth mass extinction within the Anthropocene. In response, the UN has declared 2020-2030 the Decade for Ecosystem Restoration, aiming to mitigate ecosystem degradation and biodiversity loss. Freshwater ecosystems are disproportionately impacted relative to marine or terrestrial systems and ecological restoration is needed to preserve biodiversity and ecosystem services. Paradoxically, freshwater is among Earth's most vital ecosystem services. Here we identify meaningful considerations from a freshwater perspective that will lead to progression toward the restoration of freshwater ecosystems: work across terrestrial and freshwater boundaries during restoration, emulate nature, think and act on a watershed scale, design for environmental heterogeneity, mitigate threats alongside restoration, identify bright spots, think long term (a decade is not long enough), and embrace social-ecological systems thinking. Further, we reflect upon the three implementation pathways identified by the UN to translate these considerations into practice in hopes of "bending the curve" for freshwater biodiversity and ecosystems. Pathway 1, building a global movement, could create a network to share experiences and knowledge promoting vicarious learning, ultimately leading to more effective restoration. Pathway 2, generating political support, will be necessary to institutionalize ecosystem protection and restoration by demonstrating the value of freshwater ecosystems and biodiversity. Pathway 3, building technical capacity, aims to improve
The growth and mortality parameters of Chrysichthys nigrodigitatus were estimated to assess the sustainability of its exploitation in Ikere-gorge, Oyo State, Nigeria. A total of 1210 of Chrysichthys nigrodigitatus were sampled from fishermen catches between January, 2017 and December, 2018. C. nigrodigitatus were exploited with gillnet, cast net and traps (Malian trap net and bamboo). Total lengths were measured with fish measuring board. The FAO-ICLARM Stock Assessment Tool (FiSAT II) software was used to analyze length-frequency data of the fish. The estimated growth parameters are: asymptotic length is 60.9 cm, growth coefficient is 0.96, optimum length is 38.51 cm; length at maturity is 33.44 cm while length-at-first-capture is 12.62 cm. The estimated mortality parameters are: total mortality is 3.29 per year, natural mortality is 1.43 per year and fishing mortality is 1.86. It was observed that C. nigrodigitatus of Ikere-gorge were more vulnerable to exploitation at sizes less than their length at maturity. Likewise, the exploitation rate (E = 0.57 yr-1) is greater than sustainable exploitation rate (Emax = 0.46 yr-1). This shows that exploitation of C. nigrodigitatus in Ikere-gorge is not sustainable. Therefore, there is need to reduce fishing pressure on C. nigrodigitatus to ensure its sustainability in Ikere-gorge.
The structure of a fish population is determined by the equilibrium between growth, recruitment and total mortality. But, there is paucity of information on the growth and mortality of Mormyrus rume in Nigeria. Therefore this study is needful to determine its population parameters, with a view of evolving management strategies for its sustainable exploitation. Estimates of population parameters of Mormyrus rume were obtained from length-frequency data of 836 individuals collected monthly for a period of 24 months from January 2017 to December 2018. The estimated growth parameters were: asymptotic length (L∞) was 100.8cm; growth coefficient (K) was 0.62/year; growth performance (Ɵ) was 3.8; length at maturity (Lm) was 52.57cm; reproductive load (Lm/L∞) was 0.52 and optimum length (Lopt) was 65.10cm. Likewise, natural, fishing and total mortalities were 0.93, 1.46 and 2.39 respectively. The values of exploitation rate (0.61) and ratio of total mortality and growth coefficient (3.85) showed that Mormyrus rume is most exploited in Ikere-gorge. Therefore, appropriate fishing regulations should be enforced to regulate fishing gears and mesh size that will fish Mormyrus rume at sustainable level. Keywords: Recruitment, mortality, growth, exploitation, length
Gillnet selectivity of Coptodon zillii was estimated in this study to determine the appropriate mesh size for the exploitation of the fish in Asejire dam. Holt’s indirect method of estimation was used to estimate gillnet selectivity of C. zillii in Asejire dam. Three mesh sizes 50.8mm, 63.5mm and 76.2mm were used for the estimation. The result shows that these mesh sizes caught C. zillii that were significantly different in sizes and abundant (P < 0.05). The 63.5 mm mesh size of gillnet was the most efficient; it caught 150 C. zillii with length range of 13 – 22 cm. Also, 50.8 mm mesh size caught137 C. zillii with length range of 11 – 18 cm. Likewise, 76.2 mm mesh size caught 57 C. zillii with length range 16 – 24 cm. The optimum length of 50.8 mm mesh size was 14.78 cm, 63.5 mm was 18.48 cm and 76.2 mm was 22.17 cm. Mesh size of 63.5mm is recommended as the appropriate mesh size for the exploitation of C. zillii in Asejire dam for the sustainability of the fish. This is done to prevent both recruitment and growth overfishing of C. zillii in Asejire dam. Key words: optimum length; exploitation; selection; sexual maturity; recruitment overfishing, growth overfishing
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.
customersupport@researchsolutions.com
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.