Stock assessment of Queensland east coast saddletail snapper (Lutjanus malabaricus), Australia

Abstract

In Queensland, east coast saddletail snapper (Lutjanus malabaricus) are mostly line-caught by commercial and recreational fishers, with some recreational spearfishing take. Saddletail snapper are believed to be a single stock (population) off Queensland’s east coast.

This is the first stock assessment of the Queensland 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 from financial years 1988 to 2020 including commercial logbook harvest (1988–2020), recreational, charter and Indigenous survey harvest estimates (2000–2019), length distribution data from boat-ramp surveys (2017–2020) and age-length (2018–2020).

Twenty-one model scenarios were run, covering a wide range of modelling assumptions. Base case (preferred) scenario results suggested that biomass declined between 1961 and 2017 to 19% unfished biomass. In 2020, the stock level was estimated to be 23% (13–73% range across scenarios) unfished biomass.

The harvest consistent with a biomass ratio of 60%, the Sustainable Fisheries Strategy longer-term target, was estimated at 159 t (146–348 t range across scenarios and all sectors). The recommended harvest in the 2021 financial year is 12 t (0–494 t range across scenarios) to achieve this target by 2040.