Ecosystem-based fishery enhancement through pen culture of Indian major carp Labeo catla in a tropical floodplain wetland of North Eastern Region, India, during COVID pandemic.

The present study was conducted with the objective of developing ecologically and economically feasible pen culture protocols for Labeo catla as an alternate income source for wetland fishers in the context of the COVID-19 pandemic. Yearlings of L. catla (12.33 ± 1.99 cm mean total length and 26.05 ± 6.57 g mean weight) were reared in HDPE pens (500 m2 area each) at three different stocking densities of 3 (SD3), 6 (SD6) and 9 (SD9) no. m-2 in triplicates. Fishes were fed with floating pelleted feed containing 28% crude protein and 5% crude lipid two times daily at 1.5-3% of body weight. During the culture period, fish grew from 26.05 ± 6.57 to 434.61 ± 30.63 g, 306.13 ± 10.68 g and 221.13 ± 14.92 g, respectively, at stocking densities of 3, 6 and 9 no. m-2 respectively. Weight gain percentage and specific growth rate declined with increase in stocking density. Gross fish yield increased with increase in stocking density and was highest at SD9 (657.92 ± 53.55 kg pen-1), while net fish yield increased initially from SD3 to SD6 (594.31 ± 29.72 kg pen-1) and then declined with further increase in stocking density. Important water quality parameters influencing fish growth were measured, and significant difference (p > 0.05) was not observed between treatments (inside pens) and reference site (outside pen at 10-m distance). Weight gain was positively correlated (p < 0.05) to water temperature (r = 0.989) and total phosphorus (r = 0.81). Benefit cost ratio and net return was highest at SD3 (1.61; US $518.88, respectively). Stocking density of 3 no. m-2 can be considered economically feasible for table fish production of L. catla in pens. Post pen culture, monthly income of fishers increased by 10.76-179.11%, with a mean increase of 90.57%, compared to the period of first COVID-19 wave in India. The present findings can provide an impetus for effective utilization of pen enclosures for income generation and livelihood enhancement of small-scale wetland fishers during pandemic.

Integration of pen aquaculture into ecosystem-based enhancement of small-scale fisheries in a macrophyte dominated floodplain wetland of India.

The rapid degradation, overexploitation, and encroachment of floodplain wetlands have led to considerable decline in fish diversity and production from these invaluable aquatic resources threatening livelihood of the dependent fishers. The climate change evident in the fast few decades has further aggravated the problem of eutrophication causing water stress and sedimentation leading to rampant macrophyte proliferation affecting ecological and economic functioning of these ecosystems. Macrophyte control and management needs serious attention for sustaining ecosystem services provided by these resources. In this direction, pen culture of grass carp Ctenopharyngodon idella as a biocontrol for macrophytes along with Indian major carps was implemented in a co-management mode in Beledanga, a typical floodplain wetland, a gradually shrinking, macrophyte dominated floodplain wetland in lower Ganga basin. Indian major carps Labeo catla (6.28±0.23g), Labeo rohita (5.1±0.12g), Cirrhinus mrigala (3.5±0.08g) were stocked in the ratio 4:3:3 at the rate of 20 Nos.m-2 in pens (0.1ha each) in triplicate. Grass carp (7.1±0.42g) was stocked in pen at the rate of 20Nos.m-2 in duplicate. The fishes were fed with pelleted feed twice a day at the rate of 2-3% of body weight. The seed was overwintered in pens for a period of 90 days from November 2019 to January 2020. Average weight recorded at the end of culture period was 25.13±1.70g, 18.11±0.63g, 14.53±0.87g, and 39.20±1.90g in L. catla, L. rohita, C. mrigala, and C. idella, respectively. The survival of fish ranged from 70 to 81%. Growth performance and feed utilization efficiency of grass carp were significantly higher (p<0.05) compared to other carp species. The pen culture was found to be economically viable with a benefit cost ratio of 1.53. The fishes produced were released back into the open wetland as an additional input for culture-based fisheries. The intervention along with niche-based enhanced stocking led to 24% increase in the fish production from the wetland with grass carp contributing 20-22% of the total catch with 32% increase in revenue generated by the sale of fish within a short span of 1 year. The study successfully demonstrated technological suitability and economic feasibility of pen culture in this wetland and role of grass carp as a potential biocontrol species for macrophyte management. Grass carp stocked in open wetland grew to 0.8 to 1kg within 6 months and 2-2.3kg within a year and could utilize 40-45% of the submerged and emergent macrophytes. Integration and optimization of grass carp will not only aid in habitat management of macrophyte-choked wetlands but will also boost their small-scale fisheries by converting standing macrophyte biomass into protein-rich fish biomass. The enhanced production will also cater to nutritional and livelihood security of the dependent fishers.

Impact of COVID-19 lockdown on small-scale fishers (SSF) engaged in floodplain wetland fisheries: evidences from three states in India.

The COVID-19 pandemic has created unprecedented human health crisis in recent global history with rippling social and economic effects. The outbreak in India has resulted in emergency lockdown in the country for more than 2 months, and that caused decline in the catch, demand, and supply of fish. It has severely altered the life and livelihoods of the floodplain wetland fishers. These floodplain wetlands play a key role in socio-economic development of stakeholders, by generating employment and livelihood in the studied regions. In the present study, a systematic assessment was conducted to identify the impact of lockdown on floodplain wetland fisheries in India with the aim to evaluate the impact of the COVID-19 lockdown on wetland fishing, fisheries production, income, and food access. We conducted a rapid telephonic survey covering176 wetland fishers in 3 states to document the early impacts of the pandemic and policy responses on floodplain wetland fisher households. The majority of fishers report negative impacts on production, sales, and incomes. Fishers of three Indian states Bihar, West Bengal, and Assam lost 20, 25, and 9 fishing days, respectively. About 70, 60, and 55 % fishers of floodplain wetlands of the three states admitted that lockdown made them partially jobless. Fish harvest during March to May was 32, 44, and 20 % lower than the previous years in Bihar, West Bengal, and Assam. The fishers of Bihar, West Bengal, and Assam lost income of INR 10000/-, 12500/-, and 4500/- due to lockdown. The analysis also showed that 25% of fishers each responded moderate to severe psychological impact and anxiety symptoms due to COVID-19. Demand supply gap during the lockdown led to the in 20-40 % increase in farm gate price of fishes at the wetland level. The present study is the first of its kind in India to systematically assess the impact and discusses several magnitudes on floodplain wetland fisher livelihood, income, and food access and suggests strategies and decision support.

Dynamics of phytoplankton community in seasonally open and closed wetlands in the Teesta-Torsa basin, India, and management implications for sustainable utilization.

The present study deals with the broader understanding of phytoplankton assemblage pattern and their ecohydrological interactions in two ecologically distinct floodplain wetlands of Teesta - Torsa basin, India. Analyses of data revealed significant seasonal variations (p ≤ 0.05) of ten water variables (temperature, transparency, pH, conductivity, total dissolved solids, dissolved oxygen, total hardness, total alkalinity, PO4 - P, and SiO4 - Si) in both the wetlands; however, no significant variation was observed among the sampling stations. In total, 128 species of phytoplankton were recorded (118 species belonging to 94 genera in seasonally open; 103 species belonging to 86 genera in closed wetland). Four algal groups, viz. Cyanophyceae, Coscinodiscophyceae, Bacillariophyceae, and Chlorophyceae, were the dominant quantitative component, remarkably influencing the total phytoplankton population in both the wetlands, contributing ~ 87% of total phytoplankton. Species Aulacoseira granulata alone contributed 12 - 41% and 8 - 34% to the total phytoplankton in the seasonally open and closed wetland, respectively, and indicated high organic load in both the wetlands. Altogether thirty-six and thirty-one phytoplankton taxa appeared as major indicators across the seasons for seasonally open and closed wetland, respectively. The indicator taxa (Aulacoseira, Oscillatoria, Dolichospermum, Spirogyra, Synedra, Nitzschia, Navicula, Euglena, Phacus) in both the wetlands hinted that the wetlands are under pollution pressure. The assemblage structure of phytoplankton was related to transparency, NO3 - N, PO4 - P, SiO4 - Si, total dissolved solids, and temperature as evident from BIO - ENV. Furthermore, the marginal test also selected similar variables (depth, transparency, conductivity, PO4 - P, SiO4 - Si) for seasonally open and the variables such as depth, conductivity, total dissolved solids, total alkalinity, and NO3 - N for the closed wetland. The study showed that the seasonal riverine connectivity greatly influences the variations in phytoplankton community in the seasonally open wetland.