Biological characteristics of the non-indigenous Acentrogobius pflaumii (Bleeker 1853) in a warm-temperate estuary, and thus very different from its typical environment

Abstract

The gobiid Acentrogobius plflaumii, native to estuaries and coastal embayments in East Asia, has recently established a population in the warm-temperate Swan-Canning Estuary (SCE) in southwestern Australia. Data from 432 individuals demonstrated that although A. pflaumii was shown to live for ∼4 years, the age composition was dominated by 0+ and 1+ individuals. The maximum size of female (94 mm) and male (96 mm) A. pflaumii in the SCE is 33% larger than in its native habitat. Acentrogobius plflaumii grew rapidly, attaining a length of ∼65 mm, i.e. 84 and 87% of their TL∞’s of 77.3 and 72.9 mm for females and males, respectively, within the first year of life. Gonadosomatic indices, trends in monthly gonadal development and histological examination of gonads indicate that, although peak spawning in the SCE occurs over a similar period and season as in South Korean waters, spawning is more protracted in the SCE. Two discrete modes in oocyte diameter frequencies indicate this species exhibits determinate fecundity. The protracted spawning period enables batches of eggs to be released periodically during favourable conditions. These biological traits are likely to have aided in the successful colonisation of this species in the SCE. Quantifying the phenotypic plasticity of this non-indigenous species may inform risk assessments and subsequent management plans to mitigate the effect of A. pflaumii in the SCE and predict the likelihood of it colonising other southwestern Australian estuaries.