A submarine canyon off the coast of Perth that is home to some of Western Australia’s most iconic wildlife deserves stronger protection, according to new research from Minderoo Foundation and The University of Western Australia.
The research, published in Ecosphere, shows the shallow head of the canyon is both a hotspot for marine wildlife including blue whales, southern blue fin tuna and mako sharks, and also strikingly stable over a seven-year period in terms of the number of fish, number of species, and fish biomass.
Using mid-water stereo-baited remote underwater video systems (stereo-BRUVS) and spatial modelling, lead author Dr Andrew Forrest AO, Chairman and Co-Founder of Minderoo Foundation and colleagues analysed marine life at the head of Australia’s second-largest submarine canyon over a seven-year period from 2013 to 2019.
"We now have firm evidence that the Perth canyon supports stable populations of some fish species, and that numbers of some of these species do not change greatly from year to year. We have hotspots of endangered fish in the Perth canyon that deserve protection.”Dr Andrew Forrest AO
The findings suggest that the Commonwealth Marine Reserves Review, published in 2016, which saw a zone centred over the head of the Perth canyon downgraded from ‘no take’ or national park status, to a category which allows commercial and recreational fishing, could be damaging a vast array of species.
“The argument against protecting pelagic marine park areas from fishing has often been based on the assumption that offshore populations don’t remain within or return to specific areas” Dr Forrest said.
“Our research shows that this assumption is not always correct. We now have firm evidence that the Perth canyon supports stable populations of some fish species, and that numbers of some of these species do not change greatly from year to year. We have hotspots of endangered fish in the Perth canyon that deserve protection.”
Co-author Professor Jessica Meeuwig, from UWA’s School of Biological Sciences, said the Perth canyon was a jewel in the crown of WA’s marine estate.
“Unfortunately we are not doing enough to protect this marine hotspot. Globally, many species are over or illegally fished, including southern blue fin tuna and shortfin mako, and important breeding and feeding grounds like the Perth canyon should be protected,” Professor Meeuwig said.
“Around 17 per cent of the Perth canyon is managed in highly protected zoning, well below international standards of at least 30 per cent. Our results indicate that there would be significant conservation benefits by increasing protection at the Perth canyon marine park,” Dr Forrest said.
Minderoo Foundation’s Flourishing Oceans CEO Dr Tony Worby urged the Federal Government to consider the findings and implement higher levels of protection for Perth canyon when the current management plan is reviewed in 2028.
“Minderoo Foundation will continue to work with local and Federal stakeholders to build the case for a greater level of protection for the Perth canyon and the marine species that depend on it,” Dr Worby said.
“With a growing body of evidence that shows highly protected areas improve commercial and recreational fishing, and at a time when so many targeted species are in decline, expanded protection generates benefits for both wildlife and fishers.”