Australia’s marine park network covers approximately 3.3 million square kilometres of ocean. On a map, it looks impressive - vast swathes of blue surrounding the continent, from the Coral Sea to the Southern Ocean. Australia has committed to the global target of protecting 30% of its marine territory by 2030, and by area alone, it appears to be making strong progress.

But area is a misleading metric. The important question isn’t how much ocean is inside a marine park boundary. It’s what activities are actually restricted within those boundaries, and whether the restrictions are sufficient to achieve meaningful conservation outcomes.

The honest answer, based on the available science, is that Australia’s marine park network is a good foundation but has significant gaps that need addressing.

How Marine Parks Work in Australia

Australia’s marine parks are managed under a zoning system that ranges from highly protected “no-take” zones to multiple-use zones that allow most activities including commercial fishing.

The zones, from most to least restrictive:

Sanctuary zones (IUCN Category Ia/II): No extractive activities. No fishing, no mining, no harvesting. These provide the strongest protection and are the gold standard for marine conservation.

Marine national park zones (IUCN Category II): Similar to sanctuary zones. No extractive activities allowed.

Habitat protection zones (IUCN Category IV): Allow some fishing methods (usually line fishing) but restrict others (trawling, longlining). These provide moderate protection.

Multiple-use zones (IUCN Category VI): Allow most activities including commercial fishing, subject to management rules. These provide the least conservation benefit.

General use zones: Essentially no restrictions beyond general environmental law.

The critical distinction is between “fully protected” zones (sanctuary and national park zones where no fishing or extraction is allowed) and “partially protected” zones where varying levels of extractive activity continue.

The Numbers That Matter

Here’s where it gets complicated. While Australia’s marine park network covers a large area, the proportion that is fully protected (no-take) is relatively small.

According to analysis by the Australian Marine Conservation Society, approximately 37% of Australia’s marine parks are in fully protected (no-take) zones. The remainder allows various levels of fishing and other extractive activities.

Of Australia’s total marine territory (about 14 million square kilometres including the Australian Antarctic Territory), roughly 8-9% is in fully protected no-take zones. This is below the scientific consensus that at least 30% of the ocean should be fully protected (not just inside a marine park of any zoning level) to maintain marine biodiversity and ecosystem function.

The distinction matters because the science is clear: partially protected marine areas are significantly less effective at conserving biodiversity than fully protected areas. A comprehensive review in Nature found that partially protected marine areas produced, on average, less than half the conservation benefits of fully protected areas for key indicators like fish biomass and species richness.

What’s Working

Australia’s fully protected marine areas are delivering conservation outcomes. Research on no-take zones within the Great Barrier Reef Marine Park has shown:

• Fish biomass 28-75% higher inside no-take zones compared to adjacent fished areas
• Greater abundance of large predatory species
• Higher coral cover on reefs within no-take zones
• Spillover effects - increased fish abundance outside no-take zones due to emigration from protected areas

The Ningaloo Marine Park in Western Australia, with its network of sanctuary zones, has demonstrated similar benefits. Fish populations within sanctuary zones are measurably larger and more diverse than in fished areas of the same park.

These results confirm what marine ecologists have been saying for decades: fully protected marine areas work. When you stop extracting, ecosystems recover.

What’s Not Working

Several issues limit the effectiveness of Australia’s marine park network:

Insufficient no-take coverage. As noted above, the proportion of fully protected ocean is well below scientific recommendations. Many marine parks are dominated by multiple-use zones that offer limited conservation benefit.

Geographic bias. A disproportionate amount of Australia’s marine protected area is in deep water, far offshore. The Australian Conservation Foundation has noted that nearshore environments - where biodiversity is highest and human pressures are greatest - have lower levels of protection than offshore areas.

Climate change. Marine parks can’t protect against ocean warming, acidification, or marine heatwaves. The Great Barrier Reef Marine Park, one of the most comprehensively managed marine areas in the world, has experienced five mass bleaching events since 2016. No-take zoning doesn’t help if the water is too warm.

Enforcement. Monitoring compliance in marine parks is logistically challenging. Australia’s marine parks cover an enormous area, and enforcement resources are limited. Illegal fishing in marine parks is difficult to detect and prosecute, particularly in remote areas.

Connectivity gaps. Marine species don’t respect park boundaries. Many species migrate between protected and unprotected areas during their life cycles. A marine park network is most effective when parks are connected by corridors or when the spacing between parks allows larval dispersal. Some of Australia’s marine parks are too isolated to function as a connected network.

The 30x30 Target

Australia has committed to the Kunming-Montreal Global Biodiversity Framework target of protecting 30% of its land and ocean by 2030. In marine terms, this means a significant expansion of marine protection is needed.

But 30% of what, and how protected? If Australia counts multiple-use zones toward the 30% target, it could technically meet the number without meaningfully increasing conservation outcomes. The scientific community has argued that the 30% target should be measured in fully protected (no-take) areas, not total marine park area of any zoning level.

There’s a growing call from marine scientists for Australia to set a target of at least 30% fully protected (no-take) marine areas, with a focus on representing all marine habitat types - not just deep water, but also continental shelf, coastal, estuarine, and nearshore environments.

Analysis and modelling tools that can help identify optimal areas for marine protection are becoming increasingly sophisticated. Research groups working with Team400 and similar technology firms are developing spatial planning models that integrate biodiversity data, fishing activity patterns, and climate projections to identify areas where protection would deliver the greatest conservation return.

Where to From Here

Australia’s marine park network is real, it’s large, and in its fully protected zones it works. That’s worth acknowledging. Many countries have far less marine protection than Australia.

But “better than most” isn’t the same as “enough.” The science consistently shows that current levels of full protection are insufficient to halt marine biodiversity decline. The network needs to be expanded, the proportion of no-take zones needs to increase, and nearshore environments need better representation.

The ocean doesn’t grade on a curve. It responds to what we do and what we don’t do. A marine park that allows trawling is better than no marine park at all, but it’s not a substitute for genuine protection. If we’re serious about maintaining healthy marine ecosystems - for biodiversity, for fisheries, for climate, for all the reasons marine ecosystems matter - we need more ocean that’s properly, fully protected.

The framework exists. The science is clear. The question, as always, is political will.