From sonar to drones: Fishing around for best research results

Researchers are using everything from sonar and baited cameras to traps and drones as part of a project looking at the distribution and abundance of key fishes and invertebrates in Cockburn Sound.

The Department of Primary Industries and Regional Development’s Dr Danielle Johnston, who is research lead on the project, said a wide range of methods were being used to monitor larvae, juveniles and adults of commercially, recreationally and ecologically important species. They were being sampled in various habitats and depths.

“February this year marked the end of 18 months of field work which included 220 days sampling with more than 300,000 individual fish and invertebrates identified, representing 244 taxa from 88 families,” Dr Johnston said.

She said using many methods for monitoring and assessing distribution of various species meant researchers needed to spend a lot of time in the field.

”Spring 2022 was the busiest field season to date, with 56 days of sampling, including intensive spawning biomass and larval surveys for snapper and blue swimmer crab.”

DPIRD Scientist Dr Daniel Yeoh, who is part of the WAMSI Westport Marine Science Program team and coordinating field surveys for the project, said drones were being tested to determine if they could be used for surveying changes in abundance of snapper in spawning aggregations.

“Snapper are a bigger fish and can form very dense schools near the surface, so we’re trialing drone surveys to see if we can survey them from the air.”

Sonar was proving useful for detecting schools of snapper further below the surface and the technology was also being used to study schools of smaller forage or bait fish such as sardines and anchovy.

“The acoustics work is being done in collaboration with a CSIRO team in Hobart who are leaders in these acoustic surveys.”

“There are five main species of bait fishes we are looking at including pilchards or sardines and scaly mackerel.”

He said while recreational fishers were sometimes less interested in bait fishes, they were a crucial part of Cockburn Sound’s ecology.

“Some of these species are caught for human consumption or bait, but they are particularly important as prey for penguins and dolphins and we have been providing other researchers with samples and data to use in their projects,” Dr Yeoh said.

“We are looking at what species of fish are found in Cockburn Sound and how their abundance and distribution changes throughout the year.”

“We’re also checking key water quality parameters such as temperature, salinity, dissolved oxygen and turbidity during most of our sampling.”

He said baited remote underwater video stations, which provided researchers with a close-up look at fish, will be put out at more than 150 locations this winter.

“The BRUVs are designed to spot juvenile snapper which were spawned during the last spring,” Dr Yeoh said.

“They grow throughout the year and by winter we can see them on the cameras.”

The project is a collaboration between the Department of Primary Industries and Regional Development, Murdoch University, Curtin University, Edith Cowan University and CSIRO.

Studying the sizes, seasons and whereabouts of Cockburn Sound’s squid

Innovative research in Cockburn Sound is looking at the distribution, abundance and seasonal habits of squid – a popular catch for recreational fishers.

The project is part of the WAMSI Westport Marine Science Program and designed to better understand the population of squid in the area. It is one of the first projects in Australia to try to determine localised habits of southern calamari – the main squid species in Cockburn Sound.

Dr Daniel Yeoh from the Department of Primary Industries and Regional Development, who is part of the research team, said scientists had been doing monthly sampling at up to 30 sites from Fremantle to Rockingham.

“We are looking at which areas of the Sound are most important to squid, including specific habitats and depth,” Dr Yeoh said.

“Certain habitats like seagrass generally have higher catch rates than bare sand.”

He said the exact location and depth of every squid caught was recorded using a GPS. Squid were then quickly measured and their sex noted before being released. A range of environmental parameters were recorded on each sampling occasion, including temperature, water clarity, weather and sea conditions.

“Scientists are finding out what factors influence the distribution and abundance of squid and how this is affected by environmental conditions such as temperature and water clarity. A range of biological information has also been gathered to improve the understanding of squid life cycles in Cockburn Sound,” Dr Yeoh said.

The sites selected for sampling ranged in depth from two to 15 metres and contained areas with dense seagrass meadows, areas with sparse seagrass coverage, and sandy areas with little or no vegetative cover.

“Studies in the eastern states have shown certain species of seagrass are more important for breeding and squid to lay their eggs on, so not all seagrass is the same.”

He said the research was ongoing but there were seasonal trends emerging.

“We started this research in August 2021 and the catches were moderate and then they declined in spring and summer. By the next autumn, catch rates increased.”

“Squid have a very short life cycle and only live for about one year. Their peak spawning is during spring when the large adult squid lay eggs and then die-off.

“Over summer the young squid grow and by the following autumn they reach a size where they can be caught, so catches increase.”

Dr Yeoh said most of the squid caught by the researchers were released but they were initially kept in holding tanks on the research vessels.

“Because we don’t want to catch the same squid twice, we put them in an aerated holding tank and we have found they release well. They don’t tend to release well if they’re kept in a bucket.”



Data team collecting, checking and delving into historical records

While dozens of scientists working at Cockburn Sound are busy with field trips and laboratory work, a team behind the scenes is occupied with managing huge amounts of research data while also uncovering and collating crucial historical data to feed back to the projects.

Dr Alicia Sutton, who is part of the Western Australian Marine Science Institution Location Data Management Services team, said its role was to help with quality control on current data collection and locate historical scientific information to support the WAMSI Westport Marine Science Program’s 30 projects.

“With historical data, we collate data from as far back as possible,” Dr Sutton said.

“One source of data has come from seagrass monitoring which has been collected by the Cockburn Sound Management Council for many years. This data has been provided to WAMSI researchers looking at seagrass in the Sound to provide context and allow for comparisons.”

Another example is collating data on beach profiles (measurements of the angles of the shoreline to look at variability in topography and slope) previously collected by local and State Government, which WAMSI researchers are using to understand shoreline movement across time.

“Water quality data has also been collated across industry and government bodies to help inform a water quality response model for Cockburn Sound as part of the WAMSI Westport Marine Science Program.”

Dr Sutton said collecting historical data had been challenging but it would have benefits beyond the current science program.

“In the case of data collected during the WAMSI Westport Marine Science Program, data will become publicly available and be accessible for the long term.”

“That is going to be really helpful for future projects and will allow researchers and other stakeholders to access relevant data easily, without having to contact multiple organisations and trawl through large volumes of reports,” Dr Sutton said.

The range of the data coming in from the projects of the WAMSI Westport Marine Science Program is broad. It includes spatially mapped data, photos and video footage, models, acoustic spectrograms, social surveys, laboratory and field experimental studies, biological surveys and more.

The data from the current science program, when combined with other available government and industry data has the potential to support the development of regionally specific products and science outcomes, including hydrodynamic and sediment transport models and integrated marine ecosystem biogeochemistry and ecological models.

Managing the data and keeping it safe is a big task.

Data is stored on a collaborative but secure WAMSI storage space as well as at the Pawsey Super Computing Research Centre.