Estuary perch

The estuary perch, Macquaria colonorum, is an Australian species of the Percichthyidae family.

Appearance

It is very similar to and very closely related to its sister species the Australian bass, Macquaria novemaculeata. Key differences in estuary perch are that:

• it has a slightly larger mouth and slightly more "scooped" forehead;
• it tends to remain in the estuarine reaches or (more rarely) the extreme lower freshwater reaches;
• it has a diet with more emphasis on small fish and prawns;
• it has a slightly larger growth potential than Australian Bass.

Reproduction

Estuary perch breed in winter at the same time as Australian bass, and the sexual dimorphism possessed by Australian bass and other Macquaria species — of much larger females than males — seems to be present in estuary perch as well. Out of interest, occasionally estuary perch/Australian bass hybrids are recovered; they are presumed to be non-viable.

Female estuary perch reach sexual maturity at older, larger sizes than males.

Spawning usually happens in the lower sections of estuaries and occurs from July to August in New South Wales. In the western regions of Victorian waters this happens from November to December.^[1]

Age

Estuary perch, as also many onther native fish of southeast Australia, are very long-lived. Longevity is a survival strategy to ensure that most adults participate in at least one exceptional spawning and recruitment event, which are often linked to unusually wet La Niña years and may only occur every one or two decades. Maximum recorded age is 36 years.

References

• "Macquaria colonorum". Integrated Taxonomic Information System. Retrieved 11 March 2006. 
• Froese, Rainer and Pauly, Daniel, eds. (2005). "Macquaria colonorum" in FishBase. 10 2005 version.