Reproductive strategies of two invasive tilapia species Oreochromis mossambicus and Tilapia mariae in northern Australia

Abstract

The reproductive biology of two invasive tilapia species, Oreochromis mossambicus and Tilapia mariae, resident in freshwater habitats in north-eastern Australia was investigated. Oreochromis mossambicus exhibited plasticity in some of its life-history characteristics that enhanced its ability to occupy a range of habitats. These included a shallow, weed-choked, freshwater coastal drain that was subject to temperature and dissolved oxygen extremes and water-level fluctuations to cooler, relatively high-altitude impoundments. Adaptations to harsher conditions included a decreased total length (L(T) ) and age (A) at 50% maturity (m50), short somatic growth intervals, early maturation and higher relative fecundities. Potential fecundity in both species was relatively low, but parental care ensured high survival rates of both eggs and larvae. No significant difference in the relative fecundity of T. mariae populations in a large impoundment and a coastal river was found, but there were significant differences in relative fecundities between several of the O. mossambicus populations sampled. Total length (L(T) ) and age at 50% maturity of O. mossambicus populations varied considerably depending on habitat. The L(Tm50) and A(m50) values for male and female O. mossambicus in a large impoundment were considerably greater than for those resident in a small coastal drain. Monthly gonad developmental stages and gonado-somatic indices suggested that in coastal areas, spawning of O. mossambicus and T. mariae occurred throughout most of the year while in cooler, high-altitude impoundments, spawning peaked in the warmer, summer months. The contribution these reproductive characteristics make to the success of both species as colonizers is discussed in the context of future control and management options for tilapia incursions in Australia.

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

“…mariae were recorded compared to 9 age classes (0+-8+ years) in the Mulgrave River. Also, Russell et al . (2012) noted that the average size of T .…”

“…Also, Russell et al . () noted that the average size of T . mariae from Lake Tinaroo was less than those sampled from the Mulgrave River.…”

Tilapia male urinary pheromone stimulates female reproductive axis

“…In nature, males aggregate in breeding arenas (leks) and dominant males defend small territories centred on pits (nests) that they dig in the sand, adopting a typical black colouration; visiting females spawn in the territory of a dominant male and then move away from the males to mouth brood the eggs Barata et al, 2007;Oliveira and Almada, 1998;Russell et al, 2012;Turner, 1986). Furthermore, signalling of male dominance via controlled urination has been demonstrated.…”

Egg production in the euryhaline tilapia,Sarotherodon melanotheron heudelotii, experimentally maintained in fresh, sea and hypersaline waters

“…Similar trends have been observed in fishes living in adverse environmental conditions, as regards salinity, oxygen, food availability or predation pressure, and are interpreted as trade-offs in the context of life history strategies (mosquitofish Gambusia spp., Brown-Peterson and Peterson 1990; Alcaraz and García-Berthou 2007; Caspian roach Rutilus rutilus caspicus, Naddafi et al 2005; for cichlids: Chapman 2008, 2012;Russell et al 2012). Populations of S. m. heudelotii exhibit a marked genetic structure (Ndiaye 2012) and studies of their mobility indicate that this species is rather sedentary (Diouf et al 2006).…”