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

ABSTRACT

Egg masses of ommastrephid squids are rarely found and not well studied. For the Humboldt squid, Dosidicus gigas, 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 D. gigas 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.

KEYWORDS:

• Reproduction
• embryo
• ommastrephid
• scaling
• fecundity

Acknowledgments

We would like to thank Tracy Shaw, Erin L. McLean, Ann Kelly, Jillon McGreal, Leanne Elder and Pandey Puneeta for their assistance in the field, laboratory and in preparation of this manuscript. We thank two anonymous reviewers for helpful comments on the manuscript. We thank the captain and crew of the R/V Oceanus for their assistance at sea.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the Division of Biological Infrastructure [0215393]; Division of Emerging Frontiers [1316113] to BAS; Division of Graduate Education [1244657] to MAB; Office of Experimental Program to Stimulate Competitive Research [0554548,1004057]; U.S. Department of Agriculture [2002-34438-12688,2003-34438-13111].