2024 marks the 10th anniversary of marine parks becoming operational in South Australia. Voluntary compliance is critical for the network to achieve its primary aim of protecting and conserving marine biodiversity. Currently most of the ecological monitoring and compliance effort has been focused on the Encounter Marine park as it is the closest park for over 90% of South Australia’s population. Analysis of compliance data has revealed that illegal recreational fishing is the single biggest threat to achieving the goals of the marine park. Since 2019, the incident rate of illegal recreational fishing has increased by a factor of 4 and the trend is increasing. The majority of these incidents are by first time offenders who live locally and are < 40 years of age. An analysis of ecological indicators for the same period from the Encounter marine park sanctuary zones has demonstrated little change compared to fished ‘comparison’ sites. While a return to a more natural state will take decades, it would be expected that the more sensitive biodiversity indicators might have detected a response with the removal of fishing. Understanding the sociological drivers of illegal fishing is currently the highest priority for marine park managers in South Australia.