Visible Infrared Imaging Radiometer Suite (VIIRS) Boat Detection (VBD) data have been widely used to study the patterns of fishing grounds and their linking to fishery targets, particularly species mainly caught by jiggers. In line with most species in the Ommastrephidae family, the population of Todarodes pacificus is made up of various splinter cohorts concerning the timing and location of hatching. Therefore, the satellite-recorded fishing grounds consist of groups with complex age structures and different migration directions within cohorts. This study examined the age composition of harvestable stocks (age spectrum) of T. pacificus in the Japan Sea based on an early life history individual-based model of T. pacificus and VBD data. Using the age spectrum, we analysed the relationship between fishery effort and the age of the target group. It was found that jiggers most prefer individuals around 310 ± 20 days. Furthermore, the correlation between ambient water temperature and fishing effort revealed that T. pacificus migrated to colder waters, reaching the coldest waters at 250 ± 7.5 days before moving back towards warmer waters. We discussed a possible way to use the age-temperature relationship to analyse the flow of VBD distributions to record the movements related to the migration of the fishing target. The results show migration-like trajectories, which are initially parallel to the isotherm, gradually deflect towards lower temperature sides over several months, sharply turn for about a month and then move back with a slight angle to the isotherms. The method provides a potential framework to improve our understanding of the active migration of oceanic squid.

中文翻译：

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利用卫星数据了解大洋乌贼（Ommastrephidae）迁徙路线的新方法

可见红外成像辐射计套件 (VIIRS) 船只检测 (VBD) 数据已被广泛用于研究渔场模式及其与渔业目标的联系，特别是主要由跳汰机捕获的物种。与 Ommastrephidae 科的大多数物种一样，Todarodes pacificus种群由不同的群体组成，具体取决于孵化的时间和地点。因此，卫星记录的渔场由年龄结构复杂、种群内洄游方向不同的群体组成。本研究基于太平洋砗磲早期生活史个体模型和 VBD 数据，研究了日本海太平洋砗磲可捕捞种群的年龄组成（年龄谱） 。利用年龄谱，我们分析了渔业努力量与目标群体年龄之间的关系。研究发现，跳汰机最喜欢 310 ± 20 天左右的个体。此外，环境水温与捕捞努力量之间的相关性表明，太平洋砗磲会迁移到较冷的水域，在 250 ± 7.5 天时到达最冷的水域，然后返回较温暖的水域。我们讨论了一种可能的方法，利用年龄-温度关系来分析VBD分布的流动，以记录与捕捞目标迁移相关的运动。结果显示，类似迁移的轨迹最初与等温线平行，在几个月内逐渐向温度较低的一侧偏转，在大约一个月内急剧转向，然后以与等温线呈微小角度的方式向后移动。该方法提供了一个潜在的框架，以提高我们对大洋鱿鱼主动迁徙的理解。