Identification of larval flathead fishes (family Platycephalidae) and their distribution in eastern Australian waters

Context Flathead fishes (family Platycephalidae) have economic and cultural significance, but species-specific pigmentation and morphological characteristics used for identification of larvae, and information on their distribution and seasonality, are largely unknown. Aims To infer timing and location of spawning from the spatial, seasonal and interannual distributions of the larval assemblages in eastern Australian waters. Methods DNA barcoding of flathead larvae, by using a particular gene, facilitated species-specific identification of larvae obtained from monthly samples collected between 2014 and 2021 at three oceanographic National Reference Stations (NRS) off eastern Australia. Key results Distinct larval flathead assemblages characterised each NRS, and larval diversity decreased with an increasing latitude, from seven species and six genera off North Stradbroke Island (27°S), five species and two genera at Port Hacking (34°S), to two species within the genus Platycephalus at Maria Island (42.6°S). Conclusions Larval flathead assemblages vary spatially and seasonally relating to oceanographic influences. Diversity of taxa increases towards the equator. Some species show potential of reproductive plasticity. Implications Species-specific identification of larvae enables an understanding of the larval phase of key species that are commercially and recreationally important and provides insights into spatial, seasonal and oceanographic influences on their distribution.