The Fox in the Henhouse
- 1 day ago
- 4 min read
Is Aquaculture damaging the integrity of the Jervis Bay Marine Park ecosystem?
By Rod Sleath
For over forty years, members of the Jervis Bay Divers Club have dived and explored the waters of Jervis Bay and its surrounds. Many of the Bay's best known dive sites are on the Northeast side of the bay. Iconic sites in the docks area like Deco rock, Slot Cave, Double Decker Cave and the Inner Tubes come to mind. Sites that are prime examples of Jervis Bay's clear waters, beautiful sponge gardens and prolific marine biodiversity. These are areas they thought were safe - protected by the legislative shield of the Jervis Bay Marine Park, and sitting within a sanctuary zone, the area of a marine park offered the highest level of protection.
But beneath the surface, a silent, invasive takeover is underway, and it has been invited in by the very people charged with protecting these waters.
Meet the Invader
Meet Mytilus galloprovincialis, commonly known as the Mediterranean mussel. Included on the International Union for the Conservation of Nature's (IUCN's) list of 100 of the world's worst invasive species, this mollusc is a biological powerhouse. It grows rapidly, releases more spawn than any other blue mussel species, and possesses a hardy resistance to temperature and salinity changes. Most dangerously, it hybridises with the Australian indigenous species, Mytilus planulatus, threatening the native blue mussel with genetic extinction.
Historically, Jervis Bay was not home to visually obvious populations of blue mussels. Decades of diving experience from Jervis Bay Divers Club members confirm this. Yet, since commercial mussel farming operations began in 2020, we have witnessed a dramatic shift. Shallow reefs in the north-east of Jervis Bay are being smothered with Mediterranean mussels.
Today, extensive mussel coverage is appearing on reefs down-current from the mussel farm. From Pyramid Rock under Point Perpendicular to the sanctuary zones of the Northeast Bay, the "blue mussel tide" is rising. In recent months divers are noticing mature populations forming on the southern side of the bay on mooring lines at The Nursery dive site, and on the underside of marker buoys at the regularly dived Dent Rock. It appears the mussels are slowly continuing their spread around the Bay.
Protection or Promotion?
The NSW Marine Estate Management Act 2014 states that the primary purpose of a marine park is to maintain "ecosystem integrity". Furthermore, regulations strictly forbid bringing "exotic" (explicitly defined in the regulations as non-indigenous) species into these zones.
Despite this, the Department of Primary Industries (DPI) oversaw the establishment of a commercial farm for the invasive Mediterranean mussel right in the heart of the Jervis Bay Marine Park.
Even more concerning is the lack of foresight. The DPI's investigative studies into the farm's viability allegedly failed to mention the risk of mussel spread. The only study to predict this outcome was an honours thesis from the University of Wollongong = a study supervised by the DPI's own scientists. It seems the risk was known, yet the precautionary principle, the better-safe-than-sorry approach essential to conservation, was abandoned.
Above The "harmless" Mussel Farm
The Reality on the Reef
As divers, we are the eyes underwater, seeing the reality that the policy-makers do not. Under the farm itself, mussel reefs are forming on the sand at depths of 14 metres. Outside the farm perimeter, the mussels are currently colonising rocky reefs at depths of 1 to 5 metres - but in some places they are down to 8m depth. As the mussels continue to spread over time they risk impacting on both sponge and kelp garden habitats within the bay. The damage isn't just environmental, local Jervis Bay boat owners are reporting mussel fouling on moorings and engine intakes in Callala Bay and Currumbene Creek, something they claim they never saw before the presence of the mussel farm.
A High Price for Pet Food
Perhaps the most bitter pill to swallow is the economic reality of this venture. Reports suggest the Jervis Bay Mussel farm has struggled to harvest mussels for human consumption due to effluent closures and barnacle infestations. The mussels are even said to have a bitter flavour due to local algae. Our understanding from management comments is that in the last year almost all mussels that have been marketed as Jervis Bay Mussels for human consumption, have actually been imported from Victorian mussel farms.
So, what is our Marine Park being put at risk for? Not a thriving premium seafood industry, but - according to recent reports - pet food. The integrity of a pristine Marine Sanctuary Zone is being put at risk to produce additives for pet food.
The Conflict of Interest
This situation highlights a fundamental flaw in how our marine estates are managed. Currently, the DPIRD (the department of primary industries and regional development) acts as both the protector of the Marine Park and the proponent of the aquaculture within it. It is the definition of the fox guarding the henhouse.
In land-based National Parks, we do not allow commercial agriculture to displace native biodiversity. Why is the standard different for our oceans? For our Marine Parks to be more than just "paper parks", management should sit within the department for the environment, not the department for primary industries. And our marine parks should be managed for protection of the existing biodiversity, not as a resource to be exploited at the expense of marine park ecosystem integrity.
A Call to Action
Jervis Bay is a crown jewel of the NSW coast. Its value lies in its healthy natural habitats, which drive tourism and support genuine biodiversity. The divers of Jervis Bay will continue to watch, photograph, and document changes in the Bay's ecosystem. We hope that before it is too late to reverse the damage being done, the government will remember that a Marine Park first and foremost is supposed to be a sanctuary for native regional marine biodiversity, not a farm for a non-native invasive species.
About the Author: Rod Sleath is a long-time SCUBA diver, a member of the Jervis Bay Divers Club, and a vocal advocate for marine conservation in the NSW South Coast region.
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