RESUMO
This study was conducted to observe the stock assessments of Tengara (Mystus tengara) in three different management systems of Baors (Oxbow lake) such as System-1, System-2, and System-3. In this study, 1806 specimens were sampled using traditional fishing nets to observe growth pattern, population structure, growth parameters, natural mortality (M), fishing mortality (F), total mortality (Z), recruitment pattern, exploitation rate (E), relative yield per-recruit (Y'/R), optimum catchable length, length at first capture, steady state biomass (SSB), and maximum sustainable yield (MSY) from January to December 2021. Digital slide calipers and a digital balance were used to measure each individual's total length (TL) and body weight (BW), respectively. An empirical maximum length-based model was used to calculate size at first sexual maturity (Lm), and optimum catchable length (Lopt) was calculated based on asymptotic length (L∞). The least square linear regression equation was used to determine the regression parameters. The value of regression parameter, 'b' was 3.01 for system-1, 2.78 for system-2, and 2.70 for system-3, indicating that growth pattern of Tengara is isometric in system-1, but negative allometric growth in system-2 and system-3. The highest asymptotic length (L∞) and weight (W∞) of Tengara were found in system-1 (11.19 cm and 13.67 g) in comparison with system-2, (10.98 cm and 12.49 g) and system-3 (9.09 cm and 6.96 g) respectively. The growth coefficient (K) of the von Bertalanffy growth function (VBGF) was 0.72 year-1, 0.72 year-1, and 0.73 year-1 for system-1, system-2 and system-3, respectively. The calculated M, F, Z were 1.72, 1.28, and 3.00 year-1 for system-1, 1.11, 0.67 and 1.78 year-1 for system-2 and 1.12, 0.84 and 1.96 year-1 for system-3 respectively. The calculated life span (tmax) was found 4.19 years for system-1, 4.15 years for system-2 and 4.12 years for system-3. The recruitment patterns showed that the highest relative percentage of recruits were found in July, June and September for system-1, system-2 and system-3 respectively, with the major recruitment peak occurring from April to June for system-1, May to June for system-2 and June to July for system-3. One minor recruitment peak also occurred from August to September in system-1. The exploitation rate was more or less same in all three systems indicating that Tengara is under exploited from all the Baors. The significantly highest SSB and MSY were found in system-1 (22.65 and 12.11 metric tons), compared to system-2 (16.16 and 10.28 metric tons) and system-3 (5.55 and 5.49 metric tons), respectively. Considering the values of regression parameters, recruitment pattern, SSB and MSY, system-1 was found more suitable for Tengara compared to system-2 and system-3 management practices of Baors. Finally, these findings will turn out to be paradigm for the impregnable management of Tengara in Baors of southwest Bangladesh.
RESUMO
The purpose of studying the consequence of COVID-19 on oxbow lake (Baor) fisher's community is to counteract the negative impacts on livelihoods with food security and figure out diversified resilience options for sustaining basic needs of life. Individual questionnaire interviews, oral history, focus group discussion, and telephonic interviews were among the methodological techniques used to gather primary data. The Baor fisher's community was impaired with income, food and feeding habit, health and marketing. The Baor fishers had to stop harvesting or reducing the amount of fish harvest because of gradual decreasing of consumer demand and prices of fish during the course of COVID-19 pandemic period. The transportation costs were raised up to 50%-80%, while the prices of fish decreased by 15%-30% prior to the onset of COVID-19 pandemic. The frequency of fish consumption was significantly come down to 37.5%. Many households substituted fish to farm reared hens, eggs, domestic hens and ducks, lentils, and vegetables during the period of lockdown across the country. Supply chains of fish and fish culture inputswere disrupted due to inadequacy of transportation facilities. Many school- and college-going students were dropped outduring the ongoing pandemic situation due to their financial problems (10%) and early marriage (7.5%). The secondary sources of income (labor of netting in other aquaculture farms) of Baor fisher's community were also impaired. The resilience options of this study will be helpful to minimize the sudden economic crises, ensure dynamic fish value chains and food security, protect individuals from ongoing health hazards, and promote sustainable food production systems followed by social cohesion and stabilityagainst the prevailing challenges owing to the pandemic and other natural calamities.