Western Australia’s rapidly developing octopus fishery has found new management and marketing opportunities through an unusual discovery.
By Brad Collis
The future is looking bright, starry even, for Western Australia’s octopus fishery.
Not only is it becoming an important new component of WA’s fisheries sector – expanding at the rate of 50 per cent a year between 2017 and 2022 – but the species, commonly known around Australia as the Gloomy Octopus, is not what everyone thought.
Researchers Dr Anthony Hart from the Western Australian Fisheries and Marine Research Laboratories, and Dr Michael Amor from the Western Australian Museum and Royal Botanic Gardens Victoria, have shown the erstwhile Gloomy Octopus in WA to be a different species.
After this was proven using the latest advances in evolution genetics and multivariate morphology, an Octopus Naming Working Group was set up and Octopus djinda was born. Djinda is the Noongar First Nations word for ‘star’. Its new common name is the Western Rock Octopus.
FRDC Research Portfolio manager Dr Toby Piddocke says the identification of the WA octopus as a new species has significant scientific and marketing implications.
“Firstly, to manage something properly, you've got to know what it is. To be able to distinguish between species improves catch reporting, stock assessment and our understanding generally of local marine biodiversity,” he says.
“Under our fish name standards it now also gives the WA industry a point of differentiation in the marketplace.”
Significant, sustainable growth
The identification of the Western Rock Octopus as a different species to those in eastern Australia is the latest chapter in a remarkable fisheries development. The Western Australian Octopus Interim Managed Fishery, as it is termed, is still developing but in just 13 years has grown to support 25 full time vessels, two major octopus-dedicated processing facilities, and more than 150 full-time-equivalent people servicing the sector from Geraldton to Esperance.
Between 2021 and 2022 (after the new species was identified), the fishery increased in value and harvest by 50 per cent. Major capital investment includes a new processing and export factory at Geraldton.
The harvest in 2022 was 734 tonnes and, significantly, the fishery has already earned Marine Stewardship Council (MSC) accreditation.
While some octopus species have life-history traits that demand cautious fisheries management, Octopus djinda is a robust, short-lived, fast-growing species whose natural mortality rate is currently much higher than the catch.
Anthony cites some unusual Western Australian facts that became evident during the species discovery and naming process, and which have significant implications for the commercial fishery.
“Octopus djinda arrived in WA around 800,000 years ago, then evolved into Octopus tetricus, as it moved to the east coast and New Zealand. The vast continental shelves off the south-west and southern coast of WA were ideal habitat situated within an ideal temperature profile and the species proliferated. We know the population is enormous but don’t know it's true magnitude,” he says.
The science behind the name
Toby says the WA octopus was always thought to be a different species to Octopus tetricus common to the east coast and New Zealand, but this had not been scientifically proven.
FRDC Project 2018-178 was undertaken to resolve the question and to allow a proper assessment of the species’ contribution to the Australian cephalopod fisheries harvest and for inclusion in the Status of Australian Fish Stocks Reports.
Anthony says the evolution genetics and multivariate morphology used to determine Octopus djinda as a different species employed a combination of molecular and morphological techniques.
Multivariate morphology is the simultaneous study and measurement of an organism’s physical attributes. In this case 16 morphological features were examined including the dorsal mantle length, head width, and length of the hectocotylysed arm components.
Octopus djinda was distinguished by having greater, and non-overlapping, sucker numbers on the hectocotylised arm compared to its east coast cousin. “In lay terms, the hectocotylised arm is the male reproductive arm and it is bigger and stronger than Octopus tetricus from the east coast,” Anthony says.
After the species differentiation was confirmed, a scientific manuscript proving the Octopus djinda to be a unique species was published by the journal Zootaxa.
While Octopus djinda may still wear the same downcast expression that gave its eastern cousin its gloomy nickname, its new independent identity, the Western Rock Octopus, is expected to put smiles onto the faces of its modern-day fishers.
Related FRDC Projects
2018-178: Species identification of Australia’s most significant octopus fishery – the Western Australian Common Octopus