Samarendra Behera’s research while affiliated with West Bengal University of Animal and Fishery Sciences and other places

Wetlands are the hub for aquatic macrophytes. The aquatic macrophytes are the important component of floodplain wetlands as they are used as food, fodder, herbal medicine and domestic household materials. The present study was carried out to evaluate macrophyte diversity of Potiasola beel and its impact on the beel during June 2015 to January 2017. During the study period, a total of 25 species of macrophytes were recorded. Emergent species contribute (40%) to the total macrophyes followed by submerged (28%), floating type (20%) and marginal (12%).The average standing crop of macrophyte weight was 506.39 g dry wt/m 2 in Potiasola beel. Euryale ferox was found in access quantity which may leads to less productivity of the beel also it acts as hurdle in smooth fishing practices. Therefore, immediate removal of this species is required increase the productivity as well as smooth management of the ecosystem. In addition, policy makers can give emphasis on establishing macrophyte based industries for the benefit of the surrounding fishermen community as well as for the conservation of the wetland ecosystem.

The growth, mortality, and stock assessment of Arius arius were estimated based on monthly length-frequency analysis data collected from the Hooghly-Matlah estuary of West Bengal, India from April 2017 to March 2018. The estimated growth parameters were as L ∞ = 278 mm, K = 0.97 yr-1 , and t 0 =-0.0889 years. The different mortality coefficients Z, M, and F were obtained as 5.25 yr-1 , 1.79 yr-1 , and 3.46 yr-1 , respectively. The calculated exploitation ratio (E) was found as 0.66, and the M/K value as 1.845 indicating overexploitation of the fish. The recruitment was found throughout the year with two peaks and the value of L c was found at 56.00 mm. The estimated virtual population analysis (VPA) indicated that the highest fishing mortality (F) of 3.4499 was observed at the 190-200 mm length class, followed by 3.2393 from the 180-190 mm length class. The fishery was found at the overexploitation level and measures are needed to regulate it for promoting its sustainability.

Macrophytes are important primary producers of an aquatic ecosystem and also provide food and shelter to fish and other aquatic organisms. The present study was conducted to evaluate macrophyte diversity of Borsola oxbow lake situated in Jorhat district of Assam to know the productivity of the ecosystem during June 2015 to January 2017. During the study period, a total of 28 species of macrophytes were recorded. Emergent species contribute (36%) to the total macrophyes followed by marginal (25%), submerged (21%) and floating type (18%). The average standing crop of macrophyte weight was 456.49 g dry wt/m 2 in Borsola oxbow lake. Eichhornia crasipes was the dominant species which contributed around 80% of the total macrophyte standing crop and could be the main reason for decreasing productivity of the ecosystem. It is suggested to remove the excessive macrophytes immediately from the oxbow lake by the local fishermen for improving the productivity of the ecosystem.

The correlation between sagitta otolith morphometry (length, weight, and breadth) and weight of Otolithoides pama (Hamilton, 1822) occurring in the Hooghly-Matlah estuary of West Bengal was examined for one year (February 2017 to January 2018). The sagitta otoliths were extracted, cleaned, photographed, and measured. Otolith length, weight, and breadth were recorded for each pair of sagittae. The length and weight of the fish sample, as well as those of otoliths, ranged from 51 to 327 mm, 1.1 to 270 g, 2.0 to 13.9 mm, and 0.0085 to 0.756 g, respectively. A linear relationship existed between the length and weight of otolith with the length of fish. The relationship between total fish length (TL) and otolith length (OL) was recorded as TL = 0.038 (OL) + 0.123 (R 2 = 0.799), that of total fish length (TL) and otolith weight (OW) being TL = 0.025 (OW)-0.221 (R 2 = 0.887), that of total fish length (TL) and otolith breadth being TL = 0.031 (OB) + 0.089 (R 2 = 0.781). The morphometric relationships indicated that length, weight, and breadth of otolith exhibited a high correlation with the total length of fish.

The socio-economics of six fisherwomen co-operative societies in coastal Vizianagaram district of Andhra Pradesh were studied through field surveys by interviewing a total of 185 respondents. Respondents were mostly middle aged (31 – 56 years; 61.6%) living in nuclear families (64.9%). Majority of the fisherwomen were found illiterate (88.1%). A greater proportion (84.9%) of fisherwomen involved in fish marketing as a primary occupation followed by salting and curing (9.73%) and pickling of fishes (5.4%). More than half (56.2%) of the respondents earned > Rs. 25,000 (USD$ 1 = Rs. 75) every month. The study revealed that the socio-economic condition of the fisherwomen in the study area is poor, with a high percentage of the illiteracy. Necessary steps should be taken by the Governments organizations, NGOs and respective stakeholders to improve the literacy level as well as livelihood status.

The socio-economics of six fisherwomen co-operative societies in coastal Vizianagaram district of Andhra Pradesh were studied through field surveys by interviewing a total of 185 respondents. Respondents were mostly middle aged (31 – 56 years; 61.6%) living in nuclear families (64.9%). Majority of the fisherwomen were found illiterate (88.1%). A greater proportion (84.9%) of fisherwomen involved in fish marketing as a primary occupation followed by salting and curing (9.73%) and pickling of fishes (5.4%). More than half (56.2%) of the respondents earned > Rs. 25,000 (USD$ 1 = Rs. 75) every month. The study revealed that the socio-economic condition of the fisherwomen in the study area is poor, with a high percentage of the illiteracy. Necessary steps should be taken by the Governments organizations, NGOs and respective stakeholders to improve the literacy level as well as livelihood status.

The bark extracts of the plant Zanthoxylum rhetsa have been widely used by people of Arunachal Pradesh as a mean of catching fish. Therefore, the median lethal concentration (LC 50) value of Zan-thoxylum rhetsa bark extracts on grass carp (Ctenopharyngodon idella) (Valenciennes, 1844) has been determined in the present study. The seeds of Z. rhetsa were collected from the forest of Tarak village, located in the Siang district of Arunachal Pradesh and the toxicity test was conducted in the control condition. Five different concentrations of the extract viz., 25 mg l-1 , 35 mg l-1 , 45 mg l-1 , 55 mg l-1 and 65 mg l-1 were prepared by adding the extracts proportionately to the water. The LC 50 value of Z. rhetsa against C. idella was hosted as 45 mg l-1 for 96 h exposure period. Toxicity of aqueous solution of Z. rhetsa against fingerlings of grass carp was found to be time and dose-dependent. It was found that there was a significant (p<0.05) relationship between the mortality of the treated fish with the concentration of seed extract of Z. rhetsa. A very strong correlation coefficient was found between the mortality of test fish and exposure of seed extract of Z. rhetsa (r=0.998) at different concentrations. The finding established that Z. rhesta has a potential piscicidal effect on fish and could be used widely to control unwanted fishes in aquaculture systems.