Sexing accuracy and indicators of maturation status in captive Murray cod Maccullochella peelii peelii using non-invasive ultrasonic imagery

Newman, Dane M., Jones, Paul L. and Ingram, Brett A. 2008, Sexing accuracy and indicators of maturation status in captive Murray cod Maccullochella peelii peelii using non-invasive ultrasonic imagery, Aquaculture, vol. 279, no. 1-4, pp. 113-119.

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Title Sexing accuracy and indicators of maturation status in captive Murray cod Maccullochella peelii peelii using non-invasive ultrasonic imagery
Formatted title Sexing accuracy and indicators of maturation status in captive Murray cod Maccullochella peelii peelii using non-invasive ultrasonic imagery
Author(s) Newman, Dane M.
Jones, Paul L.
Ingram, Brett A.
Journal name Aquaculture
Volume number 279
Issue number 1-4
Start page 113
End page 119
Total pages 7
Publisher Elsevier B. V.
Place of publication Amsterdam, The Netherlands
Publication date 2008-07-02
ISSN 0044-8486
1873-5622
Keyword(s) captivity
Maccullochella peelii peelii
maturation
sex identification
ultrasound
Summary Macroscopic- and histological-based assessments of gonad condition were compared with ultrasound images to determine the feasibility of this technology as a non-invasive diagnostic tool for identifying sex and assessing maturation status of Murray cod. Four age-classes (1+, 2+, 3+ and 6+ years), were sub-sampled at monthly intervals throughout their annual reproductive cycle and scanned with a 5 MHz linear transducer. An interpretation of sex was made from the resulting images and maximum cross-sectional gonad diameter and area were recorded. Fish were subsequently dissected to confirm gender, and the weights and maturation status of gonads determined and then compared with their respective image profile. Ovaries of females were usually a distinctive feature in ultrasound images, being particularly obvious in older and/or more developed fish. In contrast, the identification of male testis was more problematic. Nonetheless, identifying sex from ultrasound images was consistently achieved by recording the presence/absence of a female ovary (96% total sexing accuracy). Maximum cross-sectional ovary diameter and area were highly correlated with gonad weight (r2 = 0.90 and 0.89, respectively) suggesting that indices of maturation status, comparable to the gonadosomatic index (GSI), can be obtained non-destructively from ultrasound scans of females. A less distinct relationship occurred between these dimensions and weight of testes (r2 = 0.41). Significant increases (P < 0.05) in mean gonad index (GI, calculated from gonad diameter) occurred for most gonad development stages. However, differences in mean GI between maturation stages were confounded by phenotypic variability, indicating that GI may be limited to population level studies. Nevertheless, ultrasound images of ovaries at each development stage were visually distinctive and enabled qualitative evaluations of maturity, thereby complementing quantitative GI assessments. Repeated serial-monitoring of the same population using ultrasound appears to have great potential for tracking maturation-induced changes in broodfish.
Language eng
Field of Research 070206 Animal Reproduction
Socio Economic Objective 830399 Livestock Raising not elsewhere classified
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2008, Elsevier B.V.
Persistent URL http://hdl.handle.net/10536/DRO/DU:30017853

Document type: Journal Article
Collection: School of Life and Environmental Sciences
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