【作者】 曹少鹏；

【导师】 刘群；

【作者基本信息】 中国海洋大学 ， 渔业资源， 2007， 硕士

【摘要】 东海带鱼（Trichiurus haumela）是东海区重要经济鱼类之一,目前还没有研究在资源评估过程中引入不确定性对东海区带鱼渔业资源进行量化评估。本文应用蒙特卡罗模拟方法第一次将不确定性引入了东海带鱼的资源评估中,研究了渔业数据中不同水平的噪声和不同初次捕捞年龄对生物学参考点F_0.1和F_max估计的影响,应用其估计结果与现在的捕捞死亡系数Fcur做比较初步评估了东海带鱼渔业资源。计算结果表明:高水平的不确定性将会增加在F_0.1和F_max估计中的差异从而使其被定义为过度捕捞的可能性减小,从而导致对渔业资源状况的错误评估结论。经过比较表明:F_0.1比F_max是一更好的参考点,且东海区带鱼渔业明显处于过度捕捞状态。不同初次捕捞年龄下单位补充量渔获量的变化情况的研究表明:增大初次捕捞年龄可以减小现在的捕捞死亡率大于参考点死亡率的概率,从而增大初次捕捞年龄可以改善现在捕捞过度的资源状况。在接下来的部分本研究把东海带鱼各参数的估计值带入单位补充量渔获量模型（YPR）、单位补充量亲体量模型（SPR）和单位补充量繁殖力模型（FPR）中来评估伏季休渔制度实施后对改善东海带鱼资源状况的效果。应用Beverton-Holt动态综合模型估算伏季休渔制度实施前后带鱼单位补充量渔获量和单位补充量亲体生物量的变化,估算在不同初次捕捞年龄（tc）和年捕捞死亡系数（F）情况下带鱼的单位补充量渔获量和单位补充量亲体生物量。为了保证在保护单位补充量亲体资源量和尽量使单位补充量渔获量最大化之间取得最好的结合点,我们设置了六个不同的情况以比较优劣。应用YPR模型、SPR模型和FPR模型估算东海带鱼的生物学参考点F_0.1、F_max、F30%、F40%和Fcun20%在休渔制度实施前后的变化,结合单位补充量渔获量和单位补充量亲体量的变化来评估伏季休渔制度的效果。从研究结果来看,当开放捕鱼条件下的捕捞强度越高和开捕规格越小时,实施伏季休渔制度后体现在资源量和渔获量的增长上以及渔获质量的提高上,效果越明显。但随着开捕年龄的提高,其效果越显削弱,而且随捕捞强度的变化影响不大。从当前实施伏季休渔制度条件下的YPR、SPR和FPR分析结果来看,即使实施3个月的伏季休渔制度,由于开捕规格偏小,引起YPR、SPR和FPR均偏低。本文第一部分的研究结果表明不确定性会影响F_0.1和F_max的估计,从而影响种群资源状况的评估。为了准确地评价一种渔业的资源状况,将不确定性引入生物学参考点的估计是很有必要的。有关伏季休渔效果制度效果的评价结果表明,伏季休渔制度在开捕年龄偏低、网目尺寸偏小和强大的捕捞压力下能体现出其效果,但开捕年龄越高,伏季休渔的效果将会越弱。针对目前东海区总体渔业资源呈衰退之势且中国尚未实施TAC渔业管理的现实,综合本研究两个方面的结论,本文最后建议在严格执行伏季休渔管理的同时,配合执行开捕规格的管理。这是目前合理利用东海区渔业资源较为科学和操作性强的管理方法。更多还原

【Abstract】 The status of the hairtail （Trichiurus haumela） fishery in the East China Sea has not been quantitatively determined using biological reference points, despite its commercial importance and declining stock abundances since the mid 1990s. This is an attempt to incorporate uncertainty into the estimation of F_0.1 and F_max and make utilization of them in the fishery management. We incorporated random variation to simulate uncertainties in the fishery data. The results showed that high levels of uncertainty increased variations in F_0.1 and F_max estimation, which led to a decrease in the probability that the fishery was defined as overfished. We then compared current fishing mortality Fcur with F_0.1 and F_max and found that the hairtail fishery is being overexploited. The changes of catches at various tc revealed that increasing tc reduced the probability that Fcur is greater than FBRP, for which we concluded that increasing tc can improve the stock status of the hairtail fishery.China officially announced Summer Fishing Moratorium in the waters of the East China Sea in 1995. Although Summer Fishing Moratorium was implemented twelve years ago, its effective evaluation has not been quantitatively conducted through the utilization of biological reference points. The estimation results of the population parameters of the hairtail are used in the yield per recruit model, spawning biomass per recruit model, and spawning fecundity per recruit model to evaluate the impact of Summer Fishing Moratorium. The effect of Summer Fishing Moratorium was evaluated through calculating the changes of F_0.1, F_max, F30%, F40%, and Fcun20% and variations of yield, spawning biomass, spawning fecundity per recruit with the Beverton-Holt model. The results show that the moratorium has achieved relatively good ecological and biological benefits. The system has led to the increased yields, number of juvenile fish, and spawning fecundity of hairtail fishery in the East China Sea. However, this positive effect decreased with the increase of the age at first capture （tc） and the yields, spawning biomass, and spawning fecundity per recruit are relatively low.The first part of the thesis reveals that uncertainties will influence the estimation of biological reference points F_0.1 and F_max , which can lead to negative effect to the stock assessment of the fishery. So it is necessary and essential to incorporate uncertainties into the assessment process to quantitatively and precisely evaluate fishery stock. Results of the evaluation of Summer Fishing Moratorium suggest that the management measure has a number of limitations under current fisheries situation. Thus, we proposed that the fisheries management in the East China Sea in the future ought to implement the Summer Fishing Moratorium as a leading fisheries management measure combining with management of increasing age at first capture so that the sustainable development of the hairtail fisheries can be achieved.更多还原