CAREER: Using Otolith Chemistry to Reveal the Life History of Antarctic Toothfish in the Ross Sea, Antarctica: Testing Fisheries and Climate Change Impacts on a Top Fish Predator

南极洲罗斯海是世界上仅存的大型完整海洋生态系统之一，但正面临着商业渔业和环境变化带来的越来越大的压力。它是南大洋最具生产力的一段，支持一系列海洋生物，包括南极洋枪鱼-该地区的顶级鱼类捕食者。虽然罗斯海的洋枪鱼商业渔业继续增长，但关于洋枪鱼生态和洋枪鱼捕捞对更广泛的罗斯海生态系统的影响的基本知识仍然存在差距。认识到罗斯海的全球价值，多国南极海洋生物资源保护委员会于2016年通过了一个大型（200万平方公里）海洋保护区。这项研究将填补南极洋枪鱼知识方面的一个关键空白，加深对鱼类生态的生物-物理相互作用的理解，同时有助于了解捕鱼和环境变化对罗斯海系统的影响。这项工作将进一步提供创新工具，用于研究地理上不同的鱼类种群之间的联系，以及综合和评估大规模海洋保护区的功效。在制定参与式奖学金的综合研究和教育计划时，该项目旨在培养下一代学者参与科学-政策-公众界面，在整个研究过程中与南大洋利益相关者接触，并加深公众对南极洲的赞赏。罗斯海科学家的一个主要研究重点是更好地了解南极洋枪鱼的生活史，并测试罗斯海海洋保护区（MPA）在保护免受过度捕捞和气候变化影响方面的功效。就像树木的年轮一样，鱼的耳骨，也就是耳石，每年都会形成一层碳酸钙，吸收环境中的元素。耳石提供有关鱼类生长和周围海洋条件的信息。假设大部分的南极洋枪鱼的生命周期是由海洋环流结构，本研究采用了多学科的方法相结合的年龄和生长的工作与耳石化学测试，同时还利用GIS绘图。该项目将测量生命史参数以及过去四十年在罗斯海收集的三组不同耳石中的微量元素和稳定同位素。这些信息将用于量化南极洋枪鱼在罗斯海的生活史和时间上使用的运输途径。该项目将评估罗斯海的洋枪鱼种群是否在整个南极洲有更广泛的联系。通过比较不同时间的生活史和耳石化学数据，研究人员将评估生活史参数和空间动态的变化，并试图推断这些变化是由捕鱼还是气候变化驱动的。这些数据的空间映射将允许罗斯海MPA在保护洋枪鱼的有效性进行评估，以及可能需要进一步保护的地方。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估。

The Ross Sea, Antarctica, is one of the last large intact marine ecosystems left in the world, yet is facing increasing pressure from commercial fisheries and environmental change. It is the most productive stretch of the Southern Ocean, supporting an array of marine life, including Antarctic toothfish – the region’s top fish predator. While a commercial fishery for toothfish continues to grow in the Ross Sea, fundamental knowledge gaps remain regarding toothfish ecology and the impacts of toothfish fishing on the broader Ross Sea ecosystem. Recognizing the global value of the Ross Sea, a large (2 million km2) marine protected area was adopted by the multi-national Commission for the Conservation of Antarctic Marine Living Resources in 2016. This research will fill a critical gap in the knowledge of Antarctic toothfish and deepen understanding of biological-physical interactions for fish ecology, while contributing to knowledge of impacts of fishing and environmental change on the Ross Sea system. This work will further provide innovative tools for studying connectivity among geographically distinct fish populations and for synthesizing and assessing the efficacy of a large-scale marine protected area. In developing an integrated research and education program in engaged scholarship, this project seeks to train the next generation of scholars to engage across the science-policy-public interface, engage with Southern Ocean stakeholders throughout the research process, and to deepen the public’s appreciation of the Antarctic. A major research priority among Ross Sea scientists is to better understand the life history of the Antarctic toothfish and test the efficacy of the Ross Sea Marine Protected Area (MPA) in protecting against the impacts of overfishing and climate change. Like growth rings of a tree, fish ear bones, called otoliths, develop annual layers of calcium carbonate that incorporates elements from their environment. Otoliths offer information on the fish’s growth and the surrounding ocean conditions. Hypothesizing that much of the Antarctic toothfish life cycle is structured by ocean circulation, this research employs a multi-disciplinary approach combining age and growth work with otolith chemistry testing, while also utilizing GIS mapping. The project will measure life history parameters as well as trace elements and stable isotopes in otoliths in three distinct sets collected over the last four decades in the Ross Sea. The information will be used to quantify the transport pathways Antarctic toothfish use across their life history, and across time, in the Ross Sea. The project will assess if toothfish populations from the Ross Sea are connected more widely across the Antarctic. By comparing life history and otolith chemistry data across time, the researchers will assess change in life history parameters and spatial dynamics and seek to infer if these changes are driven by fishing or climate change. Spatially mapping of these data will allow an assessment of the efficacy of the Ross Sea MPA in protecting toothfish and where further protections might be needed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.