Skip Navigation

ICES Journal of Marine Science: Journal du Conseil 2009 66(5):811-815; doi:10.1093/icesjms/fsp145
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Sato, N.
Right arrow Articles by Munehara, H.
PubMed
Right arrow Articles by Sato, N.
Right arrow Articles by Munehara, H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© 2009 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Seasonal occurrence and sexual maturation of Japanese pygmy squid (Idiosepius paradoxus) at the northern limits of their distribution

Noriyosi Sato1, Satoshi Awata2 and Hiroyuki Munehara2

1 Division of Biosphere Science, Graduate School of Environmental Science, University, Kita-ku, Sapporo 060-0810, Japan
2 Usujiri Fisheries Station, Field Science Centre for Northern Biosphere, Hokkaido University, 152 Usujiri-cho, Hakodate 041-1613, Japan

Correspondence to N. Sato: tel: +81 138 25 3237; fax: +81 138 25 3237; e-mail: norico{at}fish.hokudai.ac.jp.

Sato, N., Awata, S., and Munehara, H. 2009. Seasonal occurrence and sexual maturation of Japanese pygmy squid (Idiosepius paradoxus) at the northern limits of their distribution. – ICES Journal of Marine Science, 66: 811–815.

The distribution of aquatic animals is limited by water temperature. However, little is known about migration patterns, overwintering, and reproduction at the extremities of their distribution. To investigate the sexual maturation of Japanese pygmy squid (Idiosepius paradoxus) and their ability to survive during winter at the northern limits of their distribution, we collected samples monthly at Usujiri in northern Japan and carried out experiments on low-temperature tolerance. Squid were collected during 4 months in autumn and early winter. In autumn, all squid were large and sexually mature, and many egg masses were found on the surface of seagrass, whereas in early winter, only small immature squid were collected. A warm north-flowing current reached the Usujiri area during autumn, so the squid were likely transported by the current and some of the small squid were recruits that hatched there. Field data and the results of experiments on tolerance of the species to low temperatures showed that it cannot survive at the low temperatures around Usujiri in winter. The migration pattern of I. paradoxus may differ from the traditional pattern for marine resources, where young fish are transported passively and do not reproduce at the extremities of their distribution.

Keywords: cephalopod, distribution, Idiosepius, overwinter, sea current, thermal tolerance

Received 31 December 2008; accepted 10 April 2009.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.