Fishing for demersal fish species, which live close to the sea floor, has been temporarily stopped along about 900 kilometres of coastline in south-west Western Australia. Authorities introduced the closure after concerns that some fish populations were declining. The ban covers a long stretch of coast and is expected to remain in place until spring 2027. When the fishery reopens, it will only allow recreational fishing rather than commercial fishing.
Another important proposal is also being considered. When fishing starts again, several large demersal recovery areas may be created where all bottom fishing will be banned. These areas are called “no-take zones” because fish cannot be taken from them. No-take zones already play an important role in Australia’s strategy to protect marine environments. However, they are usually created for conservation inside marine parks rather than to directly support fishing activities.
In the past, many fishers have not supported these zones because they reduce the areas where people can fish. Yet an important question remains: can closing certain parts of the ocean actually increase fish numbers both inside the protected areas and in nearby fishing grounds? The recent research suggests that this approach can work. Setting aside some areas as no-take zones, while maintaining normal fisheries rules elsewhere, can lead to an increase in the total number of breeding fish. This could eventually result in improved fishing conditions in the surrounding waters.
Creating a Virtual Reef
Recreational anglers highly value the golden-coloured spangled emperor fish, the focus of the research. The study was carried out in the famous Ningaloo World Heritage Area on the Western Australian coast.
Currently, about 34 per cent of Ningaloo’s waters are protected as no-take zones. This is the highest proportion of protected waters in any region of Australia. These zones were originally created to protect marine life and provide support for tourism, education, and scientific research.
However, measuring whether these protected areas also benefit fishing is difficult. To study this question, researchers created a computer model of the spangled emperor on Ningaloo Reef, dividing it into 1,800 sections and including habitat, movement, reproduction, and fishing data. This “digital twin” allowed us to test management strategies and see how fish populations could change over time.
Uncovering what’s possible
Researchers used the model to test several possible management strategies. One scenario examined what would happen if only standard fisheries management rules were applied. Another scenario tested the addition of no-take zones. We also examined what might happen if fishing were closed for five months of the year. Finally, we looked at the effects of combining all these approaches together.
The results showed that no-take zones created clear benefits. They increased the number of large mature fish and boosted the number of young fish produced. Seasonal closures also helped increase overall fish numbers. However, they were not as effective at protecting the biggest and oldest fish in the population.
The strongest results appeared when both strategies were used together. Combining no-take zones with temporary fishing closures produced the greatest increase in mature breeding fish and the highest replenishment of younger fish. The model also suggested another interesting outcome. Catch rates for recreational fishermen could double in open fishing areas close to popular access points, such as waters within about 10 kilometres of boat ramps. This happens because fish that grow inside protected zones can move into nearby waters where fishing is allowed.
Big Fish, Big Impact
Large female fish play an enormous role in maintaining healthy fish populations. As fish grow older and bigger, they produce far more eggs than younger fish. In fact, one large female fish can produce as many eggs as ten or even twelve smaller adults. No-take zones protect these large fish because they are not exposed to fishing pressure. As a result, more older fish survive and build up inside the protected areas.
Their eggs and larvae can drift into surrounding waters. This helps rebuild fish stocks and can eventually improve catches for fishers. These benefits are strongest for species that stay within a relatively small home range. Species that travel long distances may require larger or connected no-take zones to achieve similar results.
In the past, some fishers opposed protected areas because they believed the restrictions would reduce their opportunities. However, discussions with fishermen on boat ramps across Australia show that many people now recognise their long-term value.
The research suggests that carefully designed no-take zones, combined with good fisheries management in surrounding areas, can help rebuild fish populations and support better fishing in the future. Scientists have also found that studying fish in protected areas provides useful information about habitats, movement patterns, and spawning behaviours.
This knowledge can help researchers design better conservation strategies that protect important breeding areas, restore fish populations and ensure fishing remains sustainable for future generations.
