Publication Date

9-2024

Series Number

Fisheries Management Paper No. 310

ISSN

0819-4327

Publisher

Department of Primary Industries and Regional Development Western Australia

City

Perth

Abstract

The Pilbara Demersal Scalefish Resource (PDSR) includes over 60 demersal scalefish species. The resource is accessed by the Pilbara Trap Managed Fishery, Pilbara Fish Trawl (Interim) Managed Fishery, and the Pilbara Line Fishery (PTMF, PFTIMF & PLF respectively) as well as the recreational and charter fisheries.

The PDSR is managed in accordance with the North Coast Demersal Scalefish Resource Harvest Strategy (Harvest Strategy). The sustainability objectives of the PDSR are set out in the Harvest Strategy and monitored via the use of an indicator species approach, whereby the status of key species is considered representative of the status of the resource. Under this approach the spawning biomass level of red emperor (Lutjanus sebae), bluespotted emperor (Lethrinus punctulatus) and rankin cod (Epinephelus rankini) are monitored against target, threshold, and limit reference levels.

Assessments of the status of other key non-indicator species, such as goldband snapper (Pristipomoides multidens), are also undertaken periodically. In November 2023, the Department of Primary Industries and Regional Development (DPIRD) finalised the Assessment of the Status of the Pilbara Demersal Scalefish Resource (Fisheries Research Report (FRR) No. 338).

The 2023 PDSR stock assessment indicated that the relative female spawning biomass of:

  • red emperor (indicator species) had breached the limit reference level and is classified a depleted stock;
  • bluespotted emperor (indicator species) was above the threshold reference level and is classified a sustainable stock;
  • goldband snapper (retained non-indicator species) was between the limit and the threshold reference level and is classified a depleting stock; and
  • rankin cod (indicator species) was not assessed but will be included in the next periodic stock assessment for the PDSR scheduled for completion in 2026.

In accordance with the Harvest Strategy, where the status of an indicator species (or non-indicator species) breaches the threshold or limit reference level, a review is undertaken, and a management response is implemented to recover the resource within two generations (or a maximum of 20 years). A resource is considered to have recovered when the spawning biomass level of all indicator species is above the threshold reference level and being managed to the target reference level.

Model projections outlined the 2023 stock assessment estimated that the catch of red emperor needs to be reduced by at least 38% (from 2022 levels) to recover the stock to above the threshold reference level within 20 years. Given the outcomes of the 2023 stock assessment, the indicator species approach has been applied such that red emperor (high sustainability risk) is considered an indicator for the suite of species with similar biological characteristics (e.g. late maturation relative to selection by fishing gear, relatively long lived). These species include goldband snapper (also high sustainability risk), saddletail snapper (Lutjanus malabaricus), crimson snapper (Lutjanus erythropterus), and other species that share similar life history characteristics.

Similarly, bluespotted emperor (medium/acceptable sustainability risk) is considered an indicator for the suite of species with similar biological characteristics (e.g., early maturation relative to selection by fishing gear, shorter lived), including brown-striped snapper (Lutjanus vitta).

Number of Pages

9

Keywords

west coast demersal, fish, pilbara, recovery plan, stocks, species, western australia

Disciplines

Aquaculture and Fisheries | Biology | Environmental Policy | Genetics | Marine Biology | Population Biology

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