Studies were carried out from April 2016 to March 2017 for effective understanding of diversity combined with environment-influenced spatiotemporal dynamics of microfloral structure inKailash Khalwetland of Indian Sundarbans. A total of 36 phytoplankton genera were recorded from the study area. Eight major algal groups were in order of: Bacillariophyceae > Cyanophyceae > Chlorophyceae > Coscinodiscophyceae > Xanthophyceae > Euglenophyceae > Conjugatophyceae > Mediophyceae with respect to their quantitative abundance. Mean seasonal abundance was found highest in pre-monsoon (4.32 × 10³ cells l⁻¹) followed by post-monsoon (3.88 × 10³ cells l⁻¹) and monsoon (1.96 × 10³ cells l⁻¹). One-way ANOVA showed that seasonal difference in physicochemical parameters was statistically significant for temperature, DO, specific conductivity, TA, TS, Ca⁺⁺, nitrate, transparency, salinity, TH, turbidity, Mg⁺⁺and phosphate (p < 0.05). pH, temperature, total hardness, TDS nitrate, phosphate and silicate showed a close affinity with the distribution of phytoplankton community as evident from canonical correspondence analysis. Margalef richness index (3.121–3.774) and Shannon–Wiener diversity index (2.730–2.939) indicated moderately rich phytoplankton diversity in the wetland ecosystem.

An experiment was conducted to breed a near threatened Cyprinid Osteobrama belangeri in captivity through hormonal inducement. Carp pituitary extract (CPE) and three different GnRH based synthetic hormones viz., Ovaprim, Ovatide and Wova-FH were used as inducing agents. Experiment was conducted following a Completely Randomized Design (CRD). The brooders were injected with different doses of hormones and kept in the breeding hapas at 2:1 male to female ratio. All the inducing agents induced the fishes to breed, whereas no breeding was observed in the control set. Spawning success rate varied depending on the rate of inducement and the type of inducing agent used. CPE at a dose of 9mgkg−1 of female and 3mgkg−1 of male as well as the synthetic hormones at 0.5mlkg−1 of female and 0.2mlkg−1 of male brooders were found to be effective in inducing the fishes to breed in captivity. Efficacy of the synthetic hormones was significantly higher than that of CPE (P<0.05). Dose of hormone apparently affected the percentage of fertilization, egg output, hatching rate and spawn production. Administering an over-dose of the inducing agents caused early milting resulting in poor fertilization and under-dosing might cause late inducement in males. The present breeding protocol is simple and can be taken up by small breeders. It will be helpful in aquaculture and conservation of O. belangeri

Fish is an essential component of the diet of the most populace in Assam and fish farming has been one of the sources of livelihood in rural areas. Assam ranks first in fish production among North-eastern states of India. However, fish production is not sufficient to meet the demand despite having vast aquatic resources in the state. The present study was undertaken to determine the decadal growth of fish production in the state using the compound growth rate. The study also attempted modeling and forecasting of fish production in Assam using Auto-Regressive Integrated Moving Average (ARIMA) methodology. For the present study, time-series data on fish production in Assam from 1980-81 to 2018-19 was obtained from the Directorate of Fisheries, Government of Assam. Data for the period 1980-81 to 2014-15 was utilized to build an ARIMA model and validated through the remaining data from 2015-16 to 2018-19. The best suitable model for the state’s fish production was ARIMA (1,1,0) based on the values of the model selection criterion. The actual fish production and forecast values using a fitted model were in close agreement. The out-of-sample forecast values of fish production in the state for the subsequent years 2019-20 to 2022-23 showed an increasing trend from 336.97 to 358.21 thousand metric tonnes. Considering the vast aquatic resources in the state, the study calls for serious attention by policymakers, researchers, and developmental agencies for harnessing the potential of fisheries resources for making the North-east region self-sufficient in fish production as a whole and Assam in particular.