Age and growth of two newly established invasive populations of Tilapiamariae in northern Australia

Abstract

Sagittal otoliths were used to age the samples of Tilapia mariae collected from a coastal river and an impoundment. Validation of sagittae checks was achieved using both quantitative marginal increment analysis and by tetracycline marking of the otoliths of fish kept in tanks and in a farm dam. The annulus pattern on the otoliths was generally clear and their formation appeared to be temperature related and largely completed in the Austral spring around September and October. Male T. mariae grow faster and larger than females and the maximum ages of fish from the coastal river and impoundment was 9+ and 4+ years, respectively. Past fish surveys and the absence of older age classes in the impoundment population would suggest that this population was only very recently established.

Age validation, growth and mortality of introduced Tilapia zillii in Crater Lake Nkuruba, Uganda

“…; Russell et al . ). In Lake Nkuruba, the mean annual surface water temperature over the study period was 23.9 °C and the range was relatively small (21.7–25.1 °C), although it is possible that small changes in temperature could affect oxygen consumption and allocation of energy to growth.…”

“…) and Tilapia mariae (Boulenger) in northern Australia (Russell et al . ) or biannuli (2 macrozones per year) such as in the Nile tilapia in Ethiopian lakes (Yosef & Casselman ; Admassu & Casselman ) and in Lake Nabugabo in Uganda (Bwanika et al . ).…”

“…), regular seasonal variation in temperature in some tropical regions (Blake & Blake ; Panella ; Yosef & Casselman ; Russell et al . ), variation in total dissolved solids (Fagade ), photoperiod, feeding patterns, and spawning period (e.g. Morales‐Nin & Ralston ), and spawning activity and associated body condition (Nekrasov ; Booth et al .…”

“…The paucity of validated age and growth studies in tropical fish species using otoliths and other calcified structures has been attributed to a widespread assumption that growth of tropical fish is rather consistent due to the weak temperature fluctuations characteristic of many tropical environments (Brothers 1979). However, recent studies of tropical fish species have demonstrated that variation in climatic conditions in tropical regions may lead to the deposition of one annulus (one macrozone per year) such as in Tropheus moorii (Boulenger) in Lake Tanganyika (Egger et al 2004) and Tilapia mariae (Boulenger) in northern Australia (Russell et al 2013) or biannuli (2 macrozones per year) such as in the Nile tilapia in Ethiopian lakes (Yosef & Casselman 1995;Admassu & Casselman 2000) and in Lake Nabugabo in Uganda (Bwanika et al 2007). Both abiotic and biotic factors have been suggested as possible causes of formation of these growth zones (Beckman & Wilson 1995) including wet-and-dry seasonal cycles (Bwanika et al 2007), regular seasonal variation in temperature in some tropical regions (Blake & Blake 1978;Panella 1980;Yosef & Casselman 1995;Russell et al 2013), variation in total dissolved solids (Fagade 1974), photoperiod, feeding patterns, and spawning period (e.g.…”

Validation of annulus formation in sagittal otoliths of three tropical cichlids Oreochromis andersonii (Castelnau, 1861), Oreochromis macrochir (Boulenger, 1912), and Coptodon rendalli (Boulenger, 1896)

“…Furthermore, Russell et al. () found no difference in the timing of opaque zone formation between P. mariae in the wild, in a farm dam, and in tanks where fish were fed daily to satiation. A reduction in the quality and quantity of food available at low water levels is, therefore, unlikely to have contributed significantly to opaque zone formation in the otoliths of O. andersonii , O. macrochir and C. rendalli .…”