Actual fecundity of the Arctic squid Gonatus fabricii (Cephalopoda) based on the examination of a rarely encountered spent female

ABSTRACT

Gonatus fabricii (Lichtenstein, 1818) is an ecologically important squid that spends its entire life cycle within the Arctic where it is the most abundant cephalopod. Due to the rarity of mature and reproducing females, it is unknown how many eggs females spawn (actual fecundity). Among 47,000 specimens studied between 2005 and 2019 one spent, degenerated and gelatinous female with a mantle length of 230 mm was caught in West Greenland in 2019. Examination allowed the first detailed description of fecundity and spawning pattern in the species. Oocyte development shows that the most considerable maturation of mid-vitellogenic oocytes to late vitellogenic and then to ripe stages occurs immediately after the first ripe oocytes appear in the ovary. There were no ripe oocytes in the ovary or oviducts. The ovary contained an estimated 6561 oocytes and 2551 post-ovulatory follicles and hence the total fecundity was 9112. This specimen of G. fabricii realised 28.0% of its potential fecundity which is comparable to Berryteuthis magister, which also belongs to Gonatidae, and lower than in the majority of studied deep-sea squids (including other gonatids). Spent females may provide clues as to where the major spawning areas of this abundant but poorly known squid are located.

KEYWORDS:

• Reproductive biology
• reproduction
• reproductive strategy
• Gonatidae
• polar Cephalopoda

Acknowledgements

We are grateful to the ‘Initiating North Atlantic Benthos Monitoring (INAMon)’ project for providing the squid and to the scientific group and crew of the F/V ‘Helga Maria’ for the wonderful atmosphere onboard and sampling of the squid. We thank two anonymous reviewers of the manuscript and the editors Dr. Kat Bolstad and Dr. Don Colgan for their valuable comments and suggestions to improve the quality of the paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

INAMon was financially supported by the Greenland Institute of Natural Resources, North Atlantic Cooperation (nora.fo; J. nr. 510-151), Sustainable Fisheries Greenland, the Ministry for Research in Greenland (IKIIN) and the Environmental Protection Agency (Dancea) of the Ministry of Environment and Food of Denmark (J. nr. mst-112-00272). This research is also part of the Danish Presidency project in Nordic Council of Ministers, mapping seabed biodiversity and vulnerability in the Arctic and North Atlantic. H.J.T.H. thanks the Deutsche Forschungsgemeinschaft for financial support to H.J.T.H. under the grant HO 5569/2–1 that supports the Emmy Noether Junior Research Group of H.J.T.H.