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Catchability of the southern rock lobster Jasus edwardsii. I. Effects of sex, season and catch history

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Ziegler, PE and Frusher, SD and Johnson, CR and Gardner, C (2002) Catchability of the southern rock lobster Jasus edwardsii. I. Effects of sex, season and catch history. Marine and Freshwater Research, 53 (8). pp. 1143-1148. ISSN 1323-1650

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Abstract

Seasonal variation in catchability of the southern rock lobster Jasus edwardsii, was estimated in a scientific reserve in south-east Tasmania by comparing estimates of lobster density based on direct visual observations underwater with concomitant estimates from trapping surveys. Underwater density estimates of undersized and legal-sized male and female lobsters >80 mm carapace length, did not change significantly over the 14-month study period, with the exception of undersized males (<=110 mm carapace length). Sex ratios remained constant at approximately 1:1. In marked contrast, catch rates of males and females and the sex ratio of trapped lobsters varied strongly with season, implying that catchability varies seasonally and with sex. Catchability of males and females was highest in early summer and lowest in winter. Impact of capture on subsequent catchability appeared to be weak, since the ratios of tagged animals in the population observed underwater generally reflected recapture rates of tagged animals in trap catches. Recapture rates increased with size and were higher for medium-sized and large males than for similar-sized females. However, for each particular sex-size group, recapture rates remained relatively constant throughout the study period.

Item Type: Article
Keywords: lobster; Jasus edwardsii
Journal or Publication Title: Marine and Freshwater Research
Page Range: pp. 1143-1148
ISSN: 1323-1650
Identification Number - DOI: 10.1071/MF01243
Additional Information: http://www.publish.csiro.au/nid/127/issue/544.htm
Date Deposited: 21 Jun 2007
Last Modified: 18 Nov 2014 03:18
URI: http://eprints.utas.edu.au/id/eprint/1203
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