نوع مقاله : مقاله کامل علمی - پژوهشی
نویسندگان
1 دانشگاه علوم کشاورزی و منابع طبیعی گرگان
2 معاون تحقیقاتی/ مرکز تحقیقات ذخایر آبزیان آب های داخلی شیلات
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The present study has done to evaluating the exploitation status and estimating the reference points of the Caspian roach in the southeast coast of the Caspian Sea in four time periods 2009-2011, 2012-2014, 2015-2017 and 2018-2020 using the LBB model.The relative biomass (B/B0) values for the species in four time periods were calculated as 0.32, 0.14, 0.04 and 0.13, respectively, which indicated that the lowest and highest depletion rate are 68 and 96%, which are related to the first and third time periods, respectively. The ratio of fishing mortality to natural mortality (F/M) varied from 1.16 in the period of 2009-2011 to 8.79 in the period of 2015-2017. The ratios of M/K, F/K and Z/K obtained from the data of the entire sampling period were estimated as 1.44, 3.94 and 5.38, respectively. In different periods of time, the values of these indices fluctuated so that the highest value of M/K and the other two indices corresponded to the first and third periods, respectively. According to indicator B/Bmsy, the Caspian roach stock in the period of 2015-2017 was in a collapsed status and in other years it was grossly exploited. Therefore, the results of the model show that the amount of harvesting is now more than the maximum sustainable yield (MSY) and the stock is severely decreasing and in a critical state. The values of F/M and B/B0 also confirmed the greatl overfished status. In general, the results of the LBB model confirm that the fishing resources of the Caspian roach in the coastal waters of the South Caspian Sea have greatly decreased and are in danger of extinction, and it is necessary to provide more effective and strict management measures to recovery/rebulding the abundance of the Caspian roach stock and save/conserve its stock.
کلیدواژهها [English]
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