Observations of multiple pelagic egg masses from small-sized jumbo squid (<i>Dosidicus gigas</i>) in the Gulf of California

Egg masses of ommastrephid squids are rarely found and not well studied. For the Humboldt squid, <i>Dosidicus gigas</i>, only a single egg mass has been scientifically documented in the wild. Little is known about the size and spatial or temporal distribution of egg masses, or the number of eggs they contain. In this study, we report observations of six egg masses laid in the Gulf of California in May 2015. Egg mass diameters were two to four times smaller in this study compared with the previously observed mass reported in 2008, consistent with the small and large sizes, respectively, of mature female squid captured during each study. Each egg mass contained 17,000–90,000 embryos, one to two orders of magnitude lower than that estimated for the large egg mass previously observed. Egg masses were observed at 9–14 m depth on or near a thermocline. Developmental stages of embryos and paralarvae differed between egg masses. No egg masses were observed in the 13 dives before or the four dives after these masses were found, suggesting that female spawning activity is probably spatially, or perhaps temporally, patchy. Developmental heterochronies in chromatophore development between <i>D. </i><i>gigas</i> and other ommastrephid squids are discussed. Amphipods and ciliates infested the majority of masses, which is the first documented case of biota associated with wild ommastrephid egg masses.柔鱼科（Ommastrephidae）鱿鱼的卵块极少被发现，相关研究亦较为匮乏。针对洪堡鱿鱼（Dosidicus gigas），目前仅存在1例野外卵块的科学记录。学界对其卵块的尺寸、时空分布规律以及卵块内含有的卵粒数量均知之甚少。本研究报道了2015年5月在加利福尼亚湾（Gulf of California）观测到的6枚卵块。本研究中的卵块直径较2008年报道的此前唯一观测记录小2至4倍，这与两次研究中捕获的成熟雌性鱿鱼分别为小型和大型的体型大小相吻合。每枚卵块内含17000至90000枚胚胎，较此前记录的大型卵块的估算值低1至2个数量级。卵块均发现于温跃层之上或其附近的9至14米水深处。不同卵块间的胚胎与稚幼体发育阶段存在差异。在发现这批卵块前的13次下潜以及后续的4次下潜中，均未观测到其他卵块，这表明雌性鱿鱼的产卵活动可能存在空间上乃至时间上的斑块分布。本研究还探讨了洪堡鱿鱼与其他柔鱼科物种在色素细胞发育方面的发育异时性（developmental heterochronies）。多数卵块均被端足类（Amphipods）和纤毛虫（Ciliates）寄生，这是野生柔鱼科鱿鱼卵块关联生物的首例科学记录。