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The relationship between circulating ecdysteroids and chela allometry in male tanner crabs: Evidence for a terminal molt in the genus Chionoecetes

Journal of Crustacean Biology

By:
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DOI: 10.1651/S-2802.1

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Abstract

Whether male Tanner crabs, Chionoecetes bairdi, undergo a terminal molt associated with a change in claw allometry has long been debated. We measured molting hormone levels in captured male C. bairdi to assess the potential for molting. We plotted a frequency histogram of chela height to carapace width ratios and found a bimodal distribution of crabs with a ratio of approximately 0.18 separating the two modes. Male crabs with a ratio less than 0.18 were classified as "small-clawed" (SC) while crabs with a ratio greater than 0.18 were classified as "large-clawed" (LC). Circulating molting hormones between SC and LC crabs were compared. Significantly lower ecdysteroid levels were found in LC crabs, indicating that this morphotype had negligible potential for molting. Circulating ecdysteroids were measured in SC males of different shell conditions (soft, new, old, and very old) and no significant differences were found. This research suggests that the molt to LC morphology is a terminal molt. The results from this study have important implications for fisheries management because sub-legal LC males will not recruit into the fishery and removal of larger males may have long term effects on population size structure.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The relationship between circulating ecdysteroids and chela allometry in male tanner crabs: Evidence for a terminal molt in the genus Chionoecetes
Series title:
Journal of Crustacean Biology
DOI:
10.1651/S-2802.1
Volume
27
Issue:
4
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Crustacean Biology
First page:
635
Last page:
642