Relationship between empirical water temperature and spring characteristics of swordtip squid (<i>Uroteuthis eduli</i>s) caught in the eastern Tsushima Strait

We analysed the data of swordtip squid <i>Uroteuthis edulis</i> caught in the eastern Tsushima Strait, from April to September between 2012 and 2018, to consider the relationships among mantle length and body and gonad weights, associated with the estimated seasonal migratory routes and itineraries improved by the quantitative results of the tracer experiments. Our analyses have enabled us to reveal the characteristics of kensaki-type squid and the reasons for their appearance. We identified the kensaki-type <i>U. edulis</i> as male individuals, caught mainly in April–June, with long slender bodies, probably adapted to empirical duration of the cold sea water temperature in the Sea of Amakusa. Researchers and fishermen have referred to the seasonal migrating group including such males as a spring-migrating group. However, the females belonging to the spring-migrating group had no kensaki-type characteristics. Moreover, contrary to that achieved by the males, the female squid had acquired greater maturation in the spring than in any other seasons. These data demonstrated that the females continued to grow to maturation even in the cold sea waters, implying a different female strategy for reproduction from that of male squid. We are concerned that the commercially valuable kensaki-type squid may decrease in the future because the water temperature in the northern East China Sea is gradually rising, probably due to global climate change.本研究分析了2012年至2018年4月至9月间在对马海峡东部捕获的剑尖枪乌贼（Uroteuthis edulis）的相关数据，旨在探讨胴长、体重与性腺重量之间的关联，并结合示踪实验的定量结果对前期估算的季节性洄游路径与行程进行优化。通过本次分析，我们得以揭示剑尖型（kensaki-type）乌贼的特征及其出现的成因。我们将主要于4-6月捕获、体型修长纤细的剑尖型剑尖枪乌贼鉴定为雄性个体，这类个体大概率适配天草海域冷水域的常规水温持续周期。此前研究者与渔民将包含此类雄性个体的季节性洄游类群称为春季洄游群，但该春季洄游群中的雌性个体并不具备剑尖型特征。此外，与雄性个体的情况相反，雌性乌贼在春季的性腺成熟度高于其他所有季节。本研究数据表明，雌性乌贼即使处于冷水域环境中，仍能持续生长直至性成熟，这意味着雌性的繁殖策略与雄性乌贼存在显著差异。我们担忧，受全球气候变化影响，东中国海北部水温正逐渐上升，具有商业价值的剑尖型乌贼种群未来或出现数量下降的情况。

搜集汇总

背景与挑战

背景概述

该数据集分析了2012年至2018年东对马海峡捕获的剑尖鱿鱼（Uroteuthis edulis）数据，重点研究水温与鱿鱼春季特征（如体长、体重和性腺重量）的关系。研究发现，kensaki-type鱿鱼主要为雄性，适应冷水环境，而雌性在春季表现出更高的成熟度，暗示了性别差异的繁殖策略；同时，数据指出全球变暖可能导致这种商业价值鱿鱼数量减少。