The Department of Primary Industries and Regional Development (DPIRD) conducts surveys to observe the abundance, movement, growth and spawning conditions of prawns to support the management of the fishery.
This includes assessing the impact environmental factors, such as the recent marine heatwave, may have on fish habitats and prawn populations.
DPIRD principal research scientist Jason How said six fishery-independent surveys were conducted annually throughout Exmouth Gulf to gather information to assess the health of prawn stocks.
“These surveys are lunar associated, occurring around the first and third-quarter moon phase, and are conducted with the assistance of industry,” Dr How said.
“Through March and April three surveys are undertaken to provide an indication of the number of prawns which are likely to grow into a size to be caught commercially.
“A further three surveys occur from August to October to monitoring spawning as this information is then used to assess stock levels as well as inform the required management arrangements.”
Dr How said the first survey for 2025 began on Saturday 22 March, with fisheries researchers spending four nights at sea.
“The survey is undertaken using commercial trawl gear, covering 24 trawls of varying length across the Exmouth Gulf,” he said.
“Between 200 to 400 prawns are caught each run and data recorded on the size, sex and spawning conditions. The retained catch of each species is also graded and weighed.
“All information collected will be assessed and used to set the start date and area for commercial operations for the year. This helps to ensure the long-term sustainability of prawn stocks as well as maintain Marine Stewardship Council (MSC) certification for the fishery.”
Alongside the prawn stock assessment, DPIRD scientists are also looking at the habitats and environmental conditions within the fishery.
DPIRD senior research scientist Scott Evans said as part of an ongoing habitat assessment project, key sites in the Exmouth Gulf were being re-surveyed to examine the impact of recent marine heatwave conditions on critical fish habitats.
“Seagrass is a critical habitat for prawns, particularly juvenile brown tiger prawns, so understanding the extent of seagrass loss is important to inform future stock levels,” Mr Evans said.
“Climate change and climate variability continues to impact stocks, and we are aiming to get a better understanding to identify, assess and monitor critical fish habitat and the environmental conditions which may affect recruitment patterns of prawns in the fishery.
“These habitat surveys will provide information on the current extent of seagrass loss, offering an early indication on what recruitment may look like in 2026 and beyond.”
The report and findings from both surveys will be analysed with outcomes expected later this year, however the impact of the recent marine heatwave may not be evident until surveys are undertaken in 2026.
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