Spawning of the Australian freshwater fish Murray cod, Maccullochella peeli (Mitchell), in earthen ponds

Abstract

Murray cod, Maccullochella peeli, spawned naturally in earthen ponds in four consecutive breeding seasons. Spawning was induced by a rise in water temperature up to or above 20°C during spring, however, an associated rise in water level was not required. Response to the temperature rise was more rapid later in the season and increasing daylength may have also been involved. Eggs were deposited on firm substrates at depths between 0·5 and 2·3 m, and hollow pipes, logs or similar structures were not necessary to provide suitable sites for egg deposition. At two spawning sites, mud had been removed from the pond banks by the broodfish and the eggs attached to the exposed clay. At one spawning site, a male cod was observed protecting the eggs during incubation. It is suggested that high survival of cod larvae will only occur when a significant rise in water level coincides with the breeding season and as a consequence the control of water levels for irrigation and flood mitigation purposes during spring and summer has affected Murray cod to a greater extent than golden perch, Macauaria ambigua, which spawns only after a substantial rise in water level, when conditions are more favourable for larval survival.

Movement patterns and habitat selection of the Endangered eastern freshwater cod Maccullochella ikei in the Mann River, Australia

“…Tags weighed on average (± SE) 20.7 ± 0.19 g in air and had a predicted transmitting life of 365 to 420 d. Tag implantation procedures and post-operative care followed those suggested by Butler et al (2009). Fish were sexed during the implantation procedure using methods described by Rowland (1983). Fish were on average 560 ± 60.8 mm in total length (TL) (range = 462−790 mm) and 2613 ± 1110.3 g in weight (range = 1133−6987 g) for females (n = 5), and 535 ± 18.1 mm TL (range = 441−688 mm) and 1044 ± 233.5 g (range = 968−4156 g) for males (n = 20).…”

Using underwater cameras to describe the reproductive behaviour of the endangered eastern freshwater cod Maccullochella ikei

“…Radio-tags were implanted within the peritoneal cavity of 15 male and three female adult cod. Sex of cod was determined during the implantation of tags using techniques described by Rowland (1983Rowland ( , 1988 for Murray cod Maccullochella peelii peelii (Mitchell). Tagged cod were released in March 2005, 7 months prior to the breeding season.…”

“…Artificial habitats, similar to those used in the hatchery production of M. peelii peelii in ponds (Lake 1967;Rowland 1983;Cadwallader & Gooley 1985;Ingram et al 2004), were used to collect eggs and breeding information on wild M. ikei. Three, weighted 200 l, plastic drums (length = 900mm, diameter = 600 mm) were placed in pools within each of the three areas in 2005.…”

“…Lake (1967) suggested a rise in water level is required to induce spawning in a number of Australian fish species, including Maccullochella spp. However, while this appears not to be the case with M. ikei, floodplain inundation may still ultimately dictate successful recruitment, but through increased habitat and food availability rather than as a direct spawning stimulus (Lake 1967;Rowland 1983Rowland , 1992Rowland , 1998Harris & Gehrke 1991).…”

“…This includes all four freshwater cod species (Maccullochella), which have been successfully produced in hatcheries and earthen ponds under controlled conditions (Lake 1967;Rowland 1983Rowland , 1985Rowland , 1988Ingram & Rimmer 1992;Simpson & Jackson 1996;Ingram et al 2004). However, little is known of the breeding behaviour of Australia's freshwater cod in the wild.…”