Minnigiak: Forage fish ecology and population dynamics in northern Labrador under a changing climate

饲料鱼是浮游动物和顶级捕食者之间的能量漏斗，是海洋生态系统的关键营养环节。Capelin(Mallotus Villosus)、沙枪(Ammodytes spp.)和北极鳕鱼(Boreogadus Saida)是拉布拉多海的主要饲料鱼。这三个物种丰度的变化对整个生态系统产生了级联影响，包括对鱼类、海鸟和具有很高社会经济价值的海洋哺乳动物。然而，饲料鱼的分布和种群动态仍然是我们无法了解该区域海洋生态系统正在发生的变化的主要知识差距。拉布拉多北部大陆架是北极门户的一个独特区域，其特点是温度和环境条件的年际和年代际变化非常强烈。这些变化改变了初级(藻类)和次级(浮游动物)产量，以及饲料鱼的种群动态和分布。比平均水平低和暖的年份之间的交替也导致了北方物种(例如，角鱼和沙枪)和北极物种(例如，北冰洋鳕鱼)之间的重叠。这项研究计划解决的首要和新颖的问题是：环境条件的短期和长期变化如何推动大西洋-北极门户的饲料鱼种群动态？回答这个问题对于预测海洋生态系统对环境条件变化的适应能力以及预测加拿大北极北部鱼类的范围扩大至关重要。具体目标包括：(1)记录和预测与环境条件有关的海豚、沙枪鱼和北极鳕鱼的分布和丰度的变化；(2)测量北方和北极饲料鱼之间的食物生态位重叠和种间竞争；(3)确定北部生态系统中海豚招募的主要驱动因素。该计划非常新颖的部分有两个：首先，它将确定推动西北大西洋-北极门户远洋生态系统变化的机制，该门户在一个处于全球变化前沿的地区仍然是一个黑匣子。其次，船基和系泊宽带声学测深仪、环境DNA和拖网的独特组合将把饲草鱼调查的分类、空间和时间分辨率提高到大西洋-北极门户以前从未达到的水平。除了培训5名HQP外，这项研究计划还将有助于推进基于生态系统的可持续商业和文化渔业管理。最终，它将改善我们对北极海洋生态系统对气候变化的适应能力的预测。

Forage fish funnel energy between zooplankton and top predators and represent a key trophic link of marine ecosystems. Capelin (Mallotus villosus), sand lance (Ammodytes spp.) and Arctic cod (Boreogadus saida) are the main forage fish in the Labrador Sea. Variations in the abundance of these three species have cascading impacts on the whole ecosystem, including on fish, seabirds, and marine mammals with high socioeconomic value. Yet, the distribution and population dynamics of forage fish remain major knowledge gaps precluding our understanding of ongoing changes in the marine ecosystems of the region. The northern Labrador shelf is a unique area of the Arctic gateway characterized by very strong interannual and decadal variations in temperature and environmental conditions. These variations modify primary (algae) and secondary (zooplankton) productions, as well as the population dynamics and distribution of forage fish. The alternation between years colder and warmer than average also results in an overlap between boreal (e.g. capelin and sand lance) and Arctic (e.g. Arctic cod) species. The overarching and novel question this research program addresses is: How do short- and long-term variations in environmental conditions drive forage fish population dynamics at the Atlantic-Arctic gateway? Answering this question is critical to predict the resilience of marine ecosystems to changes in environmental conditions as well as to forecast the northern range expansion of boreal fish in the Canadian Arctic. Specific objectives include: (I) Documenting and forecasting changes in the distribution and abundance of capelin, sand lance and Arctic cod in relation to environmental conditions; (II) Measuring the dietary niche overlaps and interspecific competition between boreal and Arctic forage fish; and (III) Identifying the main drivers of capelin recruitment in northern ecosystems. The highly novel components of this program are twofold: First, it will identify the mechanisms driving changes in pelagic ecosystems at the northwest Atlantic-Arctic gateway, which remains a black box in a region at the forefront of global changes. Second, the unique combination of ship-based and moored broadband acoustic echosounders, environmental DNA, and trawls will increase the taxonomic, spatial, and temporal resolution of the forage fish surveys to a level never reached before at the Atlantic-Arctic gateway. In addition to training 5 HQP, this research program will contribute to advancing ecosystem-based management for sustainable commercial and cultural fisheries. Ultimately, it will improve our predictions of the resilience of Arcto-boreal marine ecosystems to climate change.