Project number: 2017-147
Project Status:
Completed
Budget expenditure: $182,000.00
Principal Investigator: Chari Pattiaratchi
Organisation: University of Western Australia (UWA)
Project start/end date: 31 Dec 2017 - 29 Dec 2021
Contact:
FRDC
TAGS
Wild Catch
Stock Assessment
Oceanography
Modelling
Fishing Gear
SPECIES
Western Rock Lobster

Need

By combining this greater coverage with information derived from commercial fishers (e.g. days when gear is drowned or lost to determine key current velocities) a purpose built webapp can be developed, hosted on an existing service, which allows fishers to asses the risks posed by ocean currents to their fishing operation before they set their gear. This would also allow for fishers to predict days when drowned gear may resurface and therefore the fishing operation may continue.

In addition to this helping the fishing operation, greater current modelling coverage over this part of the fishery will allow for the fine-scale assessment of the links between water movement and puerulus settlement. As part of FRDC project “2016-260 WRL IPA: assess causes and implications of anomalous low lobster catch rates in the shallow water areas near the centre of the Western Rock Lobster fishery” 40 additional puerulus collectors will be added to the current DOF monitoring program which will provide extensive coverage of settlement rates between Seven Mile, Dongara and Jurien Bay.

Objectives

1. Establish additional coastal radar station
2. Establish a predictive warning system for ocean conditions that can be used by the WRL fishery to improve efficiency
3. Assess the relationship between water circulation and puerulus settlement rates

Final report

Author: Charitha Pattiaratchi
Final Report • 4.83 MB
2017-147-DLD.pdf

Summary

In recent fishing seasons management changes have allowed fishers to fish pots in deep water regions at the time of the year when catch rates and beach prices are both relatively high. Some of these areas are susceptible to strong ocean currents flowing down the coast in a southward direction. When currents reach high velocities they can drag the gear floats below the surface, making the retrieval of the pots impossible. Furthermore, even faster velocities can drag fishing gear into greater water depths, resulting in their loss.
The University of Western Australia has developed a fine‐scale oceanographic velocity model, which is driven by a number of data sources, of which the primary driving input are two terrestrially‐based radar arrays placed at Greenhead and Lancelin. Expansion of this array to include a site at Dongara would provide the model with coverage over the majority of the Western Rock Lobster fishery. This increase in coverage would also provide the information needed to accurately model the currents towards the northern end of the fishery where fishers have recently had issues with pots being drowned or lost.
Critical to improving management of the Western Rock Lobster (Panulirus cygnus) fishery, as Australia’s most valuable single‐species caught fishery is an understanding of oceanographic processes that control coastal recruitment. The settlement of P. cygnus post‐larvae (puerulus), defined as the puerulus index (PI), is the annual sum of the monthly mean of puerulus abundance derived from monitoring sites over the settlement season (May – April). The PI has informed catchable lobster stock 3 to 4 years into the future. Therefore, when the PI reached a minimum in 2008 and 2009, there was no relationship to the established environmental parameters that previously correlated to the puerulus index. We examined the links between oceanographic conditions and PI through the use of hydrodynamic and particle tracking models.
Final Report • 2023-05-01
2017-147-DLD

Summary

This report emphasizes the significant influence of ocean currents and their variability on the settlement of Western Rock Lobster larvae. It introduces a web-based forecasting tool, accessible via smartphones, which offers high-resolution atmospheric and ocean data for the Western Australian coast, particularly offshore Dongara. The tool aims to enhance maritime safety and assist fishers in planning by providing improved weather and current forecasts.

Related research

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Communities
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PROJECT NUMBER • 2022-063
PROJECT STATUS:
COMPLETED

WRL Communication, Education and Engagement Program

1. Strengthen industry members' engagement: Increase the full participation by internal stakeholders in Council activities, to best enable the Council to represent the industry to government and other stakeholders. This includes industry engagement and communication of WRL IPA activities and R&D...
ORGANISATION:
Western Rock Lobster Council Inc (WRLC)