Collaborative Research: Radiometric Age Validation of the Patagonian and Antarctic Toothfishes (Dissostichus Eleginoides and D. Mawsoni)

近年来，人类在南极重新大规模利用海洋资源。与早期的海豹和捕鲸活动相反，现代的影响是针对磷虾和鳍鱼种群的，最明显的是巴塔哥尼亚洋枪鱼（Dissostichus eleginoides），但也有它的同类南极洋枪鱼（Dissostichus mawsoni）在罗斯海。牙鱼是一种宝贵的资源，在世界市场上可能会继续保持高价。然而，广泛的非法捕捞导致相当大的关注，巴塔哥尼亚洋枪鱼种群被过度捕捞。在世界其他地区，过度捕捞较大的、具有商业价值的物种导致海洋食物网的捕捞，使生态系统变得贫困，价值降低。作为南极条约体系的一部分，《南极海洋生物资源保护公约》的目标是允许捕捞，同时避免破坏南极生态系统。为了实现这一目标，渔业的可持续管理取决于可靠的年龄数据。年龄数据可以模拟人口年龄结构，从而可以估计增长率、死亡率和招募率，并用于了解人口动态。年龄数据为确定一个物种的生活史模式、建立种群动态模型以及确定在特定环境条件下哪些年龄类别容易受到过度开发的影响提供了依据。目前关于洋枪鱼的年龄和生长信息是基于年龄确定方法，这些方法未经验证，取决于具体的实验室和主要研究人员。最近，南极海洋生物资源保护委员会核可了三种使用耳石的制备方法和一套从耳石微结构估计年龄的共同标准。南极海洋生物资源保护委员会耳石网络也已启动，作为交换样本的媒介，以确保读者和实验室之间的年龄估计值具有可比性。然而，还需要做大量工作，以确保这三种方法得出的年龄估计数是准确的。其中一项成功的技术是放射性年龄测定，它利用耳石中铅-210和镭-226的不平衡作为天然计时器。这项建议汇集了一个国际合作，以审查人口年龄结构的两个洋枪鱼物种，在实验设计建立在辐射验证测试的年龄数据产生的所有三个准备方法。为了将验证部分纳入整个舌鱼种群年龄结构的研究工作中，验证工作的子样本将来自澳大利亚、新西兰、英国和法国以及美国的研究小组为种群年龄研究所采集的样本集。Moss Landing海洋实验室的科学家将使用放射性年龄测定法对巴塔哥尼亚和南极齿鱼的耳石进行独立的年龄测定。Old自治领大学的科学家们将使用一个已经建立的衰老系统来生成经过验证的年龄数据，从而可以按地理区域估计生长、死亡率和寿命。该项目将提供经验证的耳石样本集，可用作统一和验证的齿鱼年龄估计系统的基础。 这项研究将提供信息，并将向公众、决策者和国际社会传播。该项目将为这两所大学中代表性不足的学生提供机会。

Recent years have seen the re-establishment of large-scale marine resource utilization by humans in the Antarctic. In contrast to early sealing and whaling activity, the modern impact is directed on krill and finfish populations, most notably of the Patagonian toothfish (Dissostichus eleginoides), but also its congenor the Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea. Toothfish are a valuable resource and are likely to continue to command a high price in world markets. However, extensive illegal fishing has lead to considerable concern that Patagonian toothfish populations are being over-harvested. In other parts of the world, over-harvesting of larger, commercially valuable species has led to fishing down of marine food webs, leaving impoverished, less valuable ecosystems. The goal of the Convention for the Conservation of Antarctic Marine Living Resources, part of the Antarctic Treaty System, is to allow harvest while avoiding disruptions to the Antarctic ecosystem. To achieve this, the sustainable management of the fishery depends on reliable age data. Age data allow population age structure to be modeled, so that growth, mortality and recruitment rates can be estimated and used to understand population dynamics. Age data provides the basis to determine the life history pattern of a species, to model population dynamics, and to determine which age classes are vulnerable to over-exploitation under a particular set of environmental conditions. Current age and growth information for toothfish is based on age determination methodologies which are not validated and depend on the specific laboratory and principal investigator. Recently, the Commission of the Conservation of Antarctic Marine Living Resources has endorsed three preparation methodologies using otoliths and a common set of criteria for estimating age from otolith micro-structure. The CCAMLR Otolith Network has also been initiated as a medium for exchanging samples to ensure that age estimates are comparable between readers and laboratories. However, considerable work is needed to ensure that age estimates generated by the three methodologies are accurate. One technique that has been successful is radiometric age determination, which uses the disequilibria of lead-210 and radium-226 in otoliths as a natural chronometer. This proposal brings together an international collaboration to examine population age structure for both toothfish species, in an experimental design built around radiometric validation tests of age data generated by all three preparation methodologies. To integrate the validation component within an Antarctic-wide effort to examine toothfish population age structure, sub-samples for validation work will be drawn from sample sets taken for population age studies by research teams working in Australia, New Zealand, the United Kingdom and France, as well as the United States. Scientists at Moss Landing Marine Laboratories will use radiometric age determination to independently age otoliths from Patagonian and Antarctic toothfishes. Scientists at Old Dominion University will use a system already established for aging to generate validated age data, allowing growth, mortality, and longevity to be estimated by geographic areas. The project will provide validated otolith sample sets that can be used as a foundation for a unified and validated age estimation system for the toothfishes. This study will provide information which will be disseminated to the public, policy-makers and the international community. The project will provide opportunities for under-represented students at both universities.