Actual status of fishing reserves of the Yesil River

ABSTRACT In this article, the study and prediction of the state of fish resources in the Yesil River was carried out to determine the boundary reference points of the reserve and management decisions in case they are exceeded, to ensure sustainable fisheries and preserve biological diversity. Ichthyological studies, retrospective analyses and rankings of the effects of the water supply of the Yesil River on fish stocks have been carried out, critical values of the biomass of fishing reserves have been determined, as criteria for biologically safe fishing values and targets for management of fish stocks at reaching the boundary values of 24.03 tonnes have been established. According to the results of studies of basic biological indicators, it was determined that roach, bream, pike and perch populations each had an LC50 above LM50, which indicates their low utilization in the fishery industry. A strategy for management of fish stocks, recommendations for the conservation of fishery resources and their rational use has been developed as a result of these findings. The list and status of the monitored indicators for the careful management of fish stocks, as well as a list and indicators of the boundary indicators for the state of fish stocks, was established. These parameters included the fish size of 50% of the sampled fish and 50% of maturity achieved, where the LC50 was observed in the fish in question from 19 to 45.4 cm and LM50 from 12.3 to 41 cm, respectively. The minimum and maximum river levels that ranged from 111 up to 159 cm, as well as the critical value of the commercial reserve, corresponded to the boundary value of 24.03 tonnes. The results of this work will serve as the basis for making future managerial decisions, necessary for sustainable fisheries and conservation of the biological diversity of the Yesil River.

摘要 本研究针对耶西尔河（Yesil River）的鱼类资源现状开展调研与预测，旨在确定渔业保护区的边界参考阈值及阈值超标后的管理决策，以保障渔业可持续发展并保护生物多样性。本研究开展了鱼类学调查、耶西尔河补水对鱼类种群影响的回顾性分析与排序评估，确定了渔业保护区生物量的临界值，将其作为生物学安全捕捞阈值标准，并确立了鱼类种群管理目标：当种群达到24.03吨的边界阈值时需启动对应管理措施。经基础生物学指标调研结果显示，斜齿鳊、欧鳊、白斑狗鱼与河鲈种群的半致死浓度（LC50）均高于半数致死质量（LM50），表明其在渔业中的开发利用率较低。基于上述研究结果，本研究制定了鱼类种群管理策略，并提出了渔业资源保护与合理利用的相关建议。本研究确立了用于精细化鱼类种群管理的监测指标清单及其现状，同时明确了鱼类资源状态的边界指标清单与具体指标，上述参数涵盖抽样种群中50%个体的体长、50%个体达到性成熟时的体长；其中受试鱼类的半致死浓度（LC50）对应体长区间为19至45.4厘米，半数致死质量（LM50）对应体长区间为12.3至41厘米。河流水位的最小值与最大值区间为111至159厘米，其临界商业保护区生物量对应24.03吨的边界阈值。本研究成果可作为未来制定管理决策的基础，为耶西尔河的渔业可持续发展与生物多样性保护提供必要支撑。