太平洋大青鲨种群结构及其管理策略评价研究

发布时间：2018-08-05 11:45

【摘要】：大青鲨是金枪鱼延绳钓渔业的主要兼捕对象,处于海洋食物链的顶端,是海洋生态系统的高级营养生物,对维持海洋生态系统的平衡具有重要的作用。随着人类捕捞压力的增大,以及气候变化对大青鲨的生长、分布等产生的影响,太平洋大青鲨的资源可持续利用面临巨大的挑战。鉴于太平洋大青鲨种群结构研究存在较大争议,种群资源评估结果存在较大的不确定性,迫切的需要研究各种不确定条件下大青鲨种群资源的变化情况。本研究以金枪鱼延绳钓科学观察员采集的样本为基础,研究了太平洋大青鲨的种群结构现状。根据单种群、双种群和复合种群3种不同的“真实”种群结构,利用蒙特卡洛方法,模拟了太平洋大青鲨的渔业状况,以剩余产量模型和年龄结构模型为评估模型,Fmsy(最大可持续产量对应的捕捞死亡率),40/10(种群产卵群体的生物量为初始生物量的0.25),恒定的捕捞产量和恒定的捕捞死亡率为捕捞控制规则,评价了评估模型采用单种群结构和双种群结构对太平洋大青鲨的资源变化的影响。主要研究内容和结果如下:(1)根据2011年-2014年,我国金枪鱼延绳钓捕捞渔船在太平洋3个采样位点收集到的大青鲨样本,利用Cytb和COⅠ基因研究了太平洋大青鲨的种群遗传结构。Cytb和COⅠ基因序列的多样性分析表明,两个标记基因分别检测到3个变异位点,各获得4种单倍型。Cytb和COⅠ基因序列的多样性分析结果分别为:h=0.693,π=0.00100和h=0.624,π=0.00126。单倍型多样性较高,而核苷酸多样性较低。群体中性检测结果显示:Tajima’s D为非显著的正值,而FU’S FU检验为显著的负值,群体核苷酸错配分布曲线为明显的单峰,表明了群体在近期发生了种群的扩张。推算大青鲨的种群扩张时间大约发生在21-29万年前。大青鲨种群分子方差分析显示,变异主要发生在种群内部的变异,发生在种群间的变异很少(Cytb基因为3.94%,COⅠ基因为2.16%)。3个采样群体间的FST分析中,两两群体分析结果显示为非显著的群体分化。研究结果表明,太平洋大青鲨的不同地理群体之间存在广泛的基因交流,不存在群体之间明显的遗传分化。(2)根据2011年到2014年中国金枪鱼延绳钓科学观察员计划获得的观察数据,利用了广义可加模型(generalizedadditivemodels,gams)分析了生物学性状(叉长、右鳍角长、摄食等级、性别和基因型)和环境指数(海表温度、月份、经度和纬度)之间的关系。结果表明,叉长与渔获位置(经度和纬度)和性别显著相关,与海表温度具有明确的正相关。整体上,东部太平洋大青鲨的个体大于西部太平洋大青鲨的群体个体,雄性个体大于雌性个体。海表温度低于29℃时,叉长随着海表温度的升高而增大,超过29℃时,叉长随着温度的升高反而减小。叉长与摄食等级,捕捞月份和基因型没有显著的关系。右鳍角长与海表温度和渔获位置显著相关,与捕捞月份具有一定的正相关。整体上,东太平洋海域大青鲨的右鳍角长比西部太平洋大青鲨的大,8月和9月捕捞到的大青鲨的右鳍角长明显大于研究样本中其他月份捕捞到的大青鲨的右鳍角长。海表温度从27℃到29.3℃,右鳍角长随着温度的升高而减小,当海表温度大于29.3℃,捕捞到的大青鲨的右鳍角长变大。右鳍角长与摄食等级和基因型之间不存在显著的关系。根据目前对大青鲨种群结构的认识,进一步解释了太平洋大青鲨不同种群结构假设的形成机制。(3)以剩余产量模型为评估模型,蒙特卡洛方法模拟太平洋大青鲨渔业。以3种种群结构为基础,结合太平洋大青鲨生物学参数的研究结果,fmsy,40/10,恒定的捕捞产量和恒定的死亡系数四种捕捞控制规则做为管理目标,研究了12种管理策略下太平洋大青鲨的资源变动情况。结果显示:1)当“真实”种群为复合种群时,4种捕捞控制规则下,种群的生物量相对误差和捕捞死亡系数的相对误差高于单种群和双种群研究下的相对误差;2)当生长系数k提高时,生物量和捕捞死亡系数的相对误差变大;当自然死亡率增大时,生物量和捕捞死亡系数的相对误差变大,表明了现阶段高估了太平洋大青鲨的相关生物学参数;3)4种不同的捕捞控制规则中,恒定的捕捞死亡率管理目标导致了大青鲨种群的生物量低于“真实”的bmsy,不能有效的推进太平洋大青鲨种群资源的可持续利用;fmsy和40/10的管理目标虽然能获得较高的总可捕量,但其资源在后期将低于“真实”的bmsy。在短时间内,可以实现大青鲨种群的可持续利用,但是随着时间的推移,大青鲨种群生物量下降,不利于大青鲨渔业的长远发展;恒定的捕捞产量(2.3×107尾)控制规则下能获得较高的总可捕量,其资源逐渐恢复,且保持较高的生物量,并呈逐渐增加的趋势。在研究的4种捕捞控制规则中,恒定的捕捞产量策略更有利于推进太平洋大青鲨种群的可持续利用(4)采用年龄结构模型为评估模型,恒定的捕捞产量为捕捞控制规则,研究不同种群结构条件下太平洋大青鲨的资源变动情况。结果显示:1)“真实”种群为单种群时,评估模型采用单种群结构能维持较高的群体补充量,且呈现继续上升的趋势,有利于大青鲨的可持续开发,是一种科学的管理策略。当评估模型采用双种群结构时,可能导致补充群体生物量的下降。2)“真实”种群为双种群时,评估模型采用双种群结构能维持较高的群体补充量,且呈现继续上升的趋势,有利于大青鲨的可持续利用。当评估模型采用单种群结构时,在短期内,补充群体的生物量高于采用双种群的评估结果,但是,其群体补充量缓慢下降。3)“真实”种群为复合种群时,评估模型采用双种群结构能维持较稳定的群体补充量(R=7.5×106尾)。当评估模型采用单种群结构时,在短期内,补充群体的生物量高于R0,但是,在获得较高的群体补充量后开始明显下降。
[Abstract]:The Great Green shark is the main target of tuna longline fishing. At the top of the marine food chain, it is an advanced nutrient in the marine ecosystem. It plays an important role in maintaining the balance of the marine ecosystem. With the increase of the human fishing pressure and the influence of climate change on the growth and distribution of the Great Green sharks, the Pacific Ocean has the influence on the growth and distribution of the Great Green sharks. The sustainable utilization of the resources of great green sharks is facing great challenges. In view of the great controversy in the study of the population structure of the Pacific Great Green shark, the result of the population resource assessment has great uncertainty. It is urgent to study the change of the population resources of the Great Green sharks under various uncertain conditions. Based on the sample of the set, the population structure of the Pacific Great Green shark was studied. Based on 3 different "real" population structures of single, double and compound populations, the fishery status of Pacific Great Green shark was simulated by Monte Carlo method. The residual yield model and the age structure model were used as the evaluation model, Fmsy (the maximum sustainable yield). The corresponding fishing mortality rate), 40/10 (the biomass of the oviposition group was 0.25 of the initial biomass), the constant fishing production and the constant fishing mortality were the fishing control rules. The effects of the single population structure and the double population structure on the change of the resources of the Pacific Great Green shark were evaluated. (1) (1) according to the 2011 -2014, Chinese tuna longline fishing boats were collected at 3 sampling sites in the Pacific Ocean. Using the Cytb and CO I genes, the diversity analysis of the genetic structure of the population genetic structure of the Pacific Great Green shark and the sequence of the CO I gene of the Pacific Great Green shark showed that 3 mutation sites were detected by two marker genes, respectively. The diversity analysis results of 4 haplotype.Cytb and CO I gene sequences were h=0.693, PI =0.00100 and h=0.624, and the diversity of PI =0.00126. haplotypes was higher and the nucleotide diversity was lower. The results of population neutral detection showed that Tajima 's D was a non significant positive value, while FU' S FU test was a significant negative value, population nucleotide mismatch distribution. The curve is obvious single peak, indicating the population expansion in the near future. The population expansion time of the Great Green shark has been estimated about 21-29 million years ago. The variance analysis of the population of the Great Green shark population showed that the variation mainly occurred in the population, and the variation in the population was very few (Cytb gene was 3.94%, CO I was 2.16%).3 In the FST analysis among the sample groups, the results of the 22 group analysis showed a non significant group differentiation. The results showed that there were extensive genetic exchanges between different geographical groups in the Pacific Great Green sharks, and there was no obvious genetic differentiation between groups. (2) according to the Chinese tuna longline scientific observer program from 2011 to 2014 Generalizedadditivemodels (gams) was used to analyze the relationship between biological traits (fork length, right fin angle length, feeding grade, sex and genotype) and environmental index (sea surface temperature, month, longitude and latitude). The results showed that the fork length was significantly related to the location of catch (longitude and latitude) and sex, There is a clear positive correlation with the sea surface temperature. On the whole, the eastern Pacific Great Green shark is larger than the population of the Western Pacific Great Green shark. The male is larger than the female. When the sea surface temperature is below 29 degrees, the fork length increases with the rise of the sea surface temperature. When the temperature rises above 29, the fork length decreases with the increase of temperature. The right fin length has a significant correlation with the sea surface temperature and the catch position, and has a positive correlation with the fishing month. On the whole, the right fin angle of the East Pacific sea shark is larger than the Western Pacific Great Green shark. The right fin angle of the Great Green shark caught in August and September is obviously greater than that of the research. The right fin angle of the Great Green shark caught in the other month is long. The sea surface temperature is from 27 to 29.3, and the right fin angle decreases with the increase of temperature. When the sea surface temperature is greater than 29.3, the right fin angle of the captured shark is larger. The right fin angle is not significantly related to the feeding grade and genotype. The understanding of shark population structure further explained the formation mechanism of different species structure hypothesis of Pacific Great Green shark. (3) using residual yield model as evaluation model, Monte Carlo method simulated Pacific Great Green shark fishery. Based on 3 group structure, combined with the study results of biological parameters of Pacific Great Green shark, fmsy, 40/10, constant capture Four fishing control rules for fishing output and constant death coefficient were used as management objectives, and the changes of the resources of the Pacific Great Green sharks were studied under 12 management strategies. The results showed that: 1) when the "real" population was a compound population, the relative error of the relative biomass and the fishing death coefficient of the population was higher than that of the 4 fishing control rules. Relative error of single and double population studies; 2) when the growth coefficient K increased, the relative error of biomass and fishing death coefficient increased; when the natural mortality increased, the relative error of biomass and fishing death coefficient became larger, indicating that the relative biological parameters of the Pacific Great Green shark were overestimated at the present stage; 3) 4 different kinds of fishing. In the control rules, the constant fishing mortality management goal led to the lower biomass of the Great Green shark population than the "true" bmsy, which could not effectively promote the sustainable utilization of the Pacific Great Green shark population; while the management target of fmsy and 40/10 could obtain higher total catch, but its resources would be lower than "real" bmsy. in the later period. In a short period of time, the sustainable utilization of the population of great green sharks can be achieved. However, with the passage of time, the biomass of the shark population decreases, which is not conducive to the long-term development of the Great Green shark fishery; the constant fishing output (2.3 x 107 tail) control rules can obtain a higher total catch, and its resources are gradually restored and maintain high biomass, and present a high biomass. In the 4 fishing control rules, the constant fishing production strategy is more conducive to the sustainable utilization of the Pacific Great Green shark population (4) the age structure model is used as the evaluation model, and the constant fishing yield is the fishing control rule, and the change of the resources of the Pacific Great Green shark under the different population structure conditions is studied. The results are as follows: 1) when the "real" population is a single population, the evaluation model can maintain a high population supplement with a single population structure and continue to rise. It is beneficial to the sustainable development of the Great Green shark. It is a scientific management strategy. When the model uses a double population structure, it may lead to the biomass of the supplemental population. When the "real" population is.2), when the "real" population is a double population, the evaluation model can maintain a high population supplement with a double population structure, and it will continue to rise, which is beneficial to the sustainable utilization of the Great Green shark. When the "real" population is slow down.3) when the "real" population is a compound population, the evaluation model uses a double population structure to maintain a stable population supplement (R=7.5 x 106). When the model uses a single population structure, the biomass of the supplemental group is higher than that of R0 in the short term. Drop.
【学位授予单位】：上海海洋大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S931.1

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