
TY  - JOUR
A1  - Schroeder, A 
A1  - Lowry, M 
A1  - Suthers, I 
T1  - Sexual dimorphism in the red morwong, <I>Cheilodactylus fuscus</I>
JF  - Marine and Freshwater Research
JO  - Mar. Freshwater Res.
Y1  - 1994
VL  - 45
IS  - 7
SP  - 1173
EP  - 1180
KW  - 
UR  - https://doi.org/10.1071/MF9941173 
N2  - The red morwong, Cheilodactylus fuscus Castelnau (Pisces : Cheilodactylidae), is a conspicuous fish on the rocky reefs of the eastern Australian coast. Visual determination of the sex of individuals in the field is necessary to remove sex bias in home-range and associated bioaccumulation studies. A sample of 61 fish (30-50 cm fork length) was collected from spear-fishing competitions in the Sydney area, and from each fish 16 morphometric measurements were taken. A multivariate analysis revealed that, in comparison with females, males are generally larger, with a significantly larger orbit-tubercle - or horn - situated in front of each eye, a smaller eye diameter and a smaller head length. A discriminant function analysis derived from these four features correctly identified 87% of an independent sample of 40 fish. Visual appraisal of fish on the basis of the proportional length of the horns misidentified <10 % of fish >30 cm and <30% of fish 20-30 cm fork length. The orbit-tubercle in males is between 2% and 4% of the fork length and is composed of bone. According to this simplified visual technique, red morwong aggregations in the Sydney region have consistently biased sex ratios. 
ER  -

