Stock assessment of Australian east coast sea mullet (Mugil cephalus) with data to December 2020

Abstract

Australian east coast sea mullet (Mugil cephalus) are a predominantly commercially caught species. Sea mullet occur as one continuous stock (population) off the Australian east coast.

This is the third stock assessment of the Australian east coast stock. The assessment implemented a two-sex population model fit to age and length data, constructed within the Stock Synthesis modelling framework.

The model incorporated data spanning the period 1899 to 2020 including commercial harvests (1899–2020), and length and age data (1990–2020).

Eight model scenarios were run, covering a range of modelling assumptions. Base case (preferred) scenario results suggested that biomass has shown an overall decline since 1980 to 37% unfished biomass in 2021 (31–43% range across scenarios).

The harvest consistent with a biomass ratio of 50%, the Harvest Strategy target, was estimated at 4801 t (4357–5054 t range across scenarios). The recommended harvest in 2021 for all regions is 2541 t (1254–3632 t range across scenarios) to return to 50%.