Journal Article

Spatial and seasonal variation in reproductive characteristics and spawning of southern calamary (<i>Sepioteuthis australis</i>): spreading the mortality risk

Natalie A. Moltschaniwskyj and Michael A. Steer

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 61, issue 6, pages 921-927
Published in print January 2004 | ISSN: 1054-3139
Published online January 2004 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/j.icesjms.2004.06.007
Spatial and seasonal variation in reproductive characteristics and spawning of southern calamary (Sepioteuthis australis): spreading the mortality risk

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Southern calamary (Sepioteuthis australis) in Tasmania form spawning aggregations in Great Oyster Bay on the central east coast of Tasmania during spring/summer; these are targeted by commercial fishers. However, it is not known if there are similar aggregations farther south in Tasmania or at other times of the year, mainly because the species lives for less than a year. Therefore, this study describes and identifies differences in reproductive ecology of southern calamary on the east and southeast coasts of Tasmania, by sampling adults and surveying egg masses at inshore sites in both regions. Inshore populations on both coasts showed a similar seasonal trend of large gonosomatic index, reproductive output, and body size, and of greatest abundance during spring, and lowest in autumn. The number of egg masses was higher on the east coast, where mature calamary formed large spawning aggregations during spring and summer. However, there were no such aggregations during winter or autumn. Along the southeast coast, spawning activity was sporadic, resulting in isolated, low density, egg patches deposited over broader areas during spring, summer, and winter. There was no evidence of areas of seagrass or macroalgae associated with large depositions of egg masses at any time on the southeast coast. It appears that, by adopting different spawning behaviour in different locations and seasons, southern calamary may spread the risk of mortality in both space and time. The biological significance of this is unclear, particularly with respect to understanding the mechanisms that drive the development of spawning aggregations. Both spatial and seasonal spawning patterns appear to result from specific use of inshore sites at certain times of the year.

Keywords: egg deposition; reproductive ecology; seasonal patterns; spatial scale; spawning; squid

Journal Article.  4182 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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