Baseline information of reproduction parameters of an amphidromous croaker Johnius coitor (Hamilton, 1822) from Ganga river basin, India with special reference to potential influence of climatic variability

Abstract

Reproductive biology of female amphidromous croaker Johnius coitor (Hamilton, 1822) was studied for the first time from various freshwater stretches of Ganga river basin, India in relation to climatic variability. The species showed high spatial variation in reproductive phenology and capable of breeding during pre-monsoon, monsoon, post-monsoon and winter. Water temperature is the most crucial environmental parameter influencing gonadal maturation and breeding. Generalized additive model (GAM) models revealed water temperature near 23–25 °C as optimum and threshold GSI above 3 units necessary for breeding. Pre-spawning fitness (Kspawn50) and size at 50% maturity (LM50) benchmarked through Kaplan-Meier survival fit estimates were in the range 1.27–1.37 units and 19–24.5 cm respectively. First maturity of females was encountered at 11.4 cm within the size range 7.2–28.5 cm. Egg parameters in mature-ripe females ranged between 0.29–0.80 mm (diameter), 0.05–0.19 mg (weight) and 5687–121 849 eggs (absolute fecundity). Mapping of climate preferendum through LOESS smoothing technique hinted water temperatures <20 °C and >32 °C to be detrimental for attainment of pre-spawning fitness while no dependence on rainfall was observed. Based on the climato-hydrological influence on breeding and regional trends of changing climate along river Ganga, we infer minimal climate driven changes in breeding phenology of this amphidromous fish species. Results of this study may serve as baseline information for future studies assessing climate driven changes and evolutionary adaptations in croakers from river Ganga.

Exploring climate change trends in major river basins and its impact on the riverine ecology, fish catch and fisheries of the Peninsular region of India: Issues and a brief overview

“…In the Ganga River system, the temperatures have enhanced by 0.20-0.47 °C and the precipitation has been decreased by 257-580 mm over the last few decades (Das et al 2016;Sarkar et al 2019aSarkar et al , 2019b. This high variability of regional weather pattern and their impacts on aquatic ecology and fisheries have been investigated indicating vulnerabilities at various scales (Sarkar et al 2017(Sarkar et al , 2018a(Sarkar et al , 2018b(Sarkar et al , 2019a(Sarkar et al , 2019b(Sarkar et al , 2020(Sarkar et al , 2021a(Sarkar et al , 2021b(Sarkar et al , 2021cKarnatak et al 2020). Climatic variability is an important aspect of riverine ecosystem processes as thermal and hydrological regimes are linked to climate variations.…”

“…There are numerous reports on the impacts of climate change on freshwater ecosystems and fishes (Ficke et al 2007;Comte et al 2013) in different geographical locations (Schindler 2001;Mooij et al 2005;Graham & Harrod 2009;Bell et al 2011). Most of these studies are from temperate countries, there are only a few studies from the tropics (Hlohowskyj et al 1996;Sarkar et al 2017Sarkar et al , 2018aSarkar et al , 2018bSarkar et al , 2019aSarkar et al , 2019bSarkar et al , 2020Sarkar et al , 2021aSarkar et al , 2021bSarkar et al , 2021c. Revadekar et al (2012) reported profound warming in the southern peninsular region during 1970-2003.…”

Pattern of reproductive biology of the endangered golden mahseer Tor putitora (Hamilton 1822) with special reference to regional climate change implications on breeding phenology from lesser Himalayan region, India

“…The parameter following water temperature that has influence on breeding is rainfall (Sharma et al 2014), through manifestation into other water quality parameters probably by bringing sudden change. Further research is required to estimate environmental and biological breeding thresholds of T. putitora for a better understanding of climatohydrological control on natural breeding (Sarkar et al 2017(Sarkar et al , 2018Karnatak et al 2018).…”

“…Whether the stabilized breeding season of golden mahseers in Uttarakhand region is presumably 'safe' for the species under continuously changing climate needs further validation to comment upon. For this purpose, attempts need to be directed towards quantifying the breeding thresholds (environmental and biology) of Golden mahseer (Sarkar et al 2017;Karnatak et al 2018;Sarkar et al 2018). Quantification of such environmental and biological thresholds for breeding in fishes is crucial for a better understanding of population-environment interactions and assessing vulnerability of a species to climate change (Peer and Miller 2014;Whitney et al 2016).…”

Effect of extreme climatic events on fish seed production in Lower Brahmaputra Valley, Assam, India: Constraint analysis and adaptive strategies

“…On the other hand, droughtlike situations experienced in some years (2001-02, 2005-06 and 2008-09) have also affected fishery productivity considerably in the Brahmaputra valley (Das, 2009;Pathak et al, 2010;Deka et al, 2011). Previous studies discussed climate change impacts on inland fisheries in Indian rivers and their plains (Vass et al, 2009;Das et al, 2013;Sarkar et al, 2018), including those of NE region of India (Debnath et al, 2015;Bhattacharjya et al, 2017); (Saud et al, 2012). There are a few studies that assessed the impact of climate change on breeding and fish seed production as well as vulnerability in India (Dey et al, 2007;Das et al, 2011;Sharma et al, 2014;Sarkar et al, 2019).…”