Tuna Tracking with Chemistry: A Test of the Two-Stock Hypothesis for Atlantic Bluefin Tuna

研究人员希望表明，蓝鳍金枪鱼的耳石化学成分，特别是Sr/Ca和Ba/Ca在微尺度分辨率和高分析精度下的测量，将成为识别跨大西洋迁徙、种群混合和产卵栖息地的决定性信号。大西洋蓝鳍金枪鱼（Thunnus thynnus）种群结构是目前渔业管理中最具争议的问题之一。争议集中在大西洋蓝鳍金枪鱼的管理上，根据两种种群模型，假设在地中海和墨西哥湾有独立的产卵地。到目前为止，还没有生物学证据支持这一假设。研究人员提出，可以对蓝鳍金枪鱼耳石的元素化学进行分析，以检验双种群假说，并获得有关个体鱼类产卵习性和栖息地的信息。耳石的微成分分析可以用来将单个鱼类与特定的水文环境联系起来，假设示踪剂按照其在周围海水中的浓度的比例被纳入耳石中，或者通过与温度相关的分馏。在任何时间内聚集的鱼都会共享一个独立于遗传身份的多元素指纹，这可以用来描绘种群和确定种群结构。

The investigators hope to show that the otolith chemistry of bluefin tuna, specifically Sr/Ca and Ba/Ca measured at microscale resolution and with high analytical precision, will be a definitive signal in the recognition of trans-Atlantic migrations, stock mixing, and spawning habitats. The stock structure of Atlantic bluefin tuna (Thunnus thynnus) is currently one of the most controversial issues in fisheries management. The controversy centers on the management of Atlantic bluefin according to a two-stock model that assumes independent spawning grounds in the Mediterranean Sea and Gulf of Mexico. To date, there is no biological evidence to support this assumption. The investigators propose that the elemental chemistry of bluefin tuna otoliths can be analyzed to test the two-stock hypothesis and yield information about the spawning habits and habitats of individual fish. Microconstituent analysis of otoliths can be used to link individual fish to a particular hydrographic environment assuming that tracers are either incorporated into the otolith in proportion to their concentration in the surrounding seawater or by a temperature-dependent fractionation. Fish that aggregate for any length of time will share a multi-elemental fingerprint independent of genetic identity, which can be used to delineate stocks and determine population structure.