Stock assessment of eastern king prawn (Melicertus plebejus) along Australia’s east coast, with data to October 2024

Abstract

Eastern king prawn, Melicertus plebejus (Hess, 1865), is a key species targeted by the Ocean Trawl Fishery in New South Wales and the East Coast Otter Trawl Fishery in Queensland. The fishery is generally considered to have commenced in 1958 and extends from the Swain Reefs in Queensland to Eden in New South Wales, and, to a lesser extent, Victoria. Eastern king prawn have a lifespan of up to three years and can grow to a maximum carapace length of 73 millimetres for females and 52 millimetres for males. Females reach maturity from 38-42 millimetres carapace length at around four months of age.
The last assessment estimated the stock at 38–81% of unfished levels in the 2019 fishing year. Several key aspects of this assessment differ from the previous assessment. Firstly, membership of the project team that guides the assessment was expanded to include a commercial fishery stakeholder and an independent scientist. Secondly, this assessment benefited from updated data through to October 2024. Thirdly, line-trawl patterns of fishing were incorporated into the calculation of fishing power. Finally, a second fishing power scenario for New South Wales was calculated using regional gear data and modelling, combined with Queensland gear data.
The assessment used a spatial, length structured two sex model with a monthly time step, fitted to standardised catch rates, length composition data and commercial size grading data. The model incorporated New South Wales and Queensland data spanning the period 1958–2024, collected from the commercial sectors, port monitoring, fishery independent beam trawl survey, commercial grading data from industry and research data.
The results of this assessment indicated that in the 2024 fishing year, the biomass ratio in 2024 was between 54% and 88% of 1958 unfished levels. The most likely estimate was 72% in 2024.