Physical characteristics, and proximate composition of oocytes, liver and muscle of wild caught and tank-reared Macquarie perch

Abstract

Macquarie perch (Macquaria australasica) is a freshwater percichthyid endemic to south-eastern Australia. In view of its conservation status (indeterminate), and its importance as a sport fish, natural stocks are replenished through a breeding programme using mature stock taken from the wild each year. This paper is the first of a series of investigations instigated to understand the underlying causes of the lack of response of Macquarie perch, caught from the wild and spawned and then tankreared for a year, to hypophysation techniques. In this paper, results of physical characteristics, proximate composition and ovarian histology of wild-caught and tank-reared fish (injected with salmon GnRHa and non-injected) are presented. Oocyte diameter distribution patterns indicate that Macquarie perch spawn once each year, and that in tank-reared fish oocyte maturation is incomplete with only a small proportion of oocytes reaching maturation. The mean (SD) gonadosomatic and hepatosomatic indices of wild fish were 11.25 (2.38) and 0.59 (0.10) and that of tank-reared fish were 4.84 (0.70) and 1.44 (0.09) respectively. These two parameters differed significantly (~~0.05) in the two groups of fish.Major differences also existed in the proximate composition of the liver and the way the liver components responded to GnRHa injection. The percent (SD) protein, lipid and ash by dry weight in the liver of wild injected fish were 57.02 (0.66), 30.63 (1.22) and 8.24 (0.05) respectively while in the liver of tank-reared uninjected fish these values were 30.87 (1.36) 24.59 (1.18) and 6.43 (0.13) respectively. When expressed as an absolute amount or an amount kg-' body weight, all of moisture, protein, lipid, ash and nitrogen free extract were greater in tank-reared than wild fish. No significant differences were observed between wild and tank-reared fish in the composition of the body musculature or the oocytes.

A Global Analysis of the Relationship between Concentrations of Microcystins in Water and Fish

“…P. fluviatilis(Łuczynska et al, 2016), Esox lucius, Salmo fario, Cyprinus carpio, Lota vulgaris(Atwater, 1891), and Macquaria australasica(Sheikh-Eldin et al, 1995). The resulting M AFDW for O. eperlanus and G. cernua was 0.9764 g (Equation 2).…”

Effects of river impoundment on body condition and reproductive performance of the Australian native fish, Macquarie perch (Macquaria australasica)

“…The mean egg radius was determined from minimum and maximum egg diameters for each individual fish (based on 145 egg measurements) and assuming that oocytes were spherical, and that all mature oocytes were released at once during a spawn (Sheikh‐Eldin et al 1995). The theoretical volume of an oocyte was calculated using the equation:…”

“…Induced breeding of reservoir‐caught Macquarie perch has been carried out successfully from the mid 1980s to the present, and the resulting young have been used to replenish depleted natural stocks. The broodfish used for hypophysation, after a short period of rehabilitation in ponds, are also returned to the wild as these fish do not respond to hypophysation in the following year (Sheikh‐Eldin et al 1995). However, in recent times, the success of artificial propagation techniques on Macquarie perch collected from Lake Dartmouth has declined (Ingram & Gooley 1996).…”

“…However, in recent times, the success of artificial propagation techniques on Macquarie perch collected from Lake Dartmouth has declined (Ingram & Gooley 1996). Investigations on the inability to artificially propagate Macquarie perch broodfish, caught from the wild, spawned and then reared in a pond environment in subsequent years have been the subject of previous studies (Sheikh‐Eldin et al 1995, 1996).…”