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The biology of the sea mullet, Mugil Cephalus L. 1758, Yellow-Eye Mullet, Aldrichetta Forsteri (Valenciennes, 1836) and the Perth Herring, Nematalosa Vlamingh (Munro, 1956), in the Swan-Avon river system, Western Australia

Chubb, Christopher (1984) The biology of the sea mullet, Mugil Cephalus L. 1758, Yellow-Eye Mullet, Aldrichetta Forsteri (Valenciennes, 1836) and the Perth Herring, Nematalosa Vlamingh (Munro, 1956), in the Swan-Avon river system, Western Australia. PhD thesis, Murdoch University.

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Abstract

An extensive sampling programme over 3.5 years, and an examination of the records of the Western Australian Museum, yielded a checklist of 122 species and 62 families of fishes for the estuary of the Swan-Avon river system. These data were then used to categorise the way in which each species utilised the estuary.

The biology of three marine species, namely the sea mullet (Mugil cephalus), yellow-eye mullet (Aldrichetta forsteri) and Perth herring (Nematalosa vlaminghi) was examined in detail. Length-frequency histograms and the seasonal nature of the commercial catch provided information on the migratory movements of M. cephalus, A. forsteri and N. vlaminghi. Spawning in the first two species occurs at sea in the winter whereas in the last species it takes place in the upper estuary in the summer. While the 0+ and 1+ year classes of each species predominated in the estuary, the 3+ and 4+ year classes of the Perth herring were also common. The mean total lengths attained at the end of the first year of life by the sea mullet, yellow-eye mullet and Perth herring were 178-222 mm (=64-119 g), 136-154 mm (=19-30 g) and 97-110 mm C= 8-11 g). Rapid growth resulted in many M. cephalus reaching the legal size for capture in just over 12 months whereas comparable values for A. forsteri and N. vlaminghi were at least 17 and 24 months respectively. The von Bertalanffy growth equation for Perth herring was Lt= 381[1 - e-0.17(t+o.65]. An analysis of commercial catch data for the Perth herring in the Swan-Avon estuary and local marine waters, showed seasonal and annual trends, and demonstrated that this important fishery is in no immediate danger of overexploitation.

Macroscopic and histological studies of the ovaries of Perth herring produced qualitative and quantitative data on aspects of gonadal development in N. vlaminghi. Attention was focussed on changes in the diameter of the oocyte, oocyte nucleus, yolk granules and the thickness of the theca, granulosa and zona radiata. At sexual maturity, the mean number of hyaline oocytes was 20,430, which represented 35% of the mean number of all yolked oocytes (57,610).

Item Type: Thesis (PhD)
Murdoch Affiliation: School of Environmental and Life Sciences
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Potter, Ian
URI: http://researchrepository.murdoch.edu.au/id/eprint/50279
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