Larger and more abundant legal-sized targeted fish inside ‘no take’ areas of a subtropical marine park over a 12-year period

Abstract

Context Multiple-use marine parks vary spatially in how they are managed, which may influence ecological response over time. Aims We surveyed four key targeted species (snapper, Chrysophrys auratus; pearl perch, Glaucosoma scapulare; venus tuskfish, Choerodon venustus; grey morwong, Nemadactylus douglasi) during winter of 6 years between 2010 and 2023 to examine management influence on abundance and length. Methods Using stereo-baited remote underwater video (BRUVs), we compared relative abundance, occurrence at legal and sublegal sizes, and length in three types of management areas within and adjacent a subtropical marine park (‘no take’; ‘partially protected’; and ‘outside’) over time by using generalised linear mixed models. ‘Partially protected’ and ‘outside’ are fished areas, managed under spatial or fishery management rules (i.e. legal-size limits). Key results Snapper, pearl perch, and venus tuskfish were consistently more abundant and larger in ‘no take’ areas than in fished areas, especially legal-sized or larger individuals (>30 cm). Grey morwong showed a weak response in its abundance among management areas but was larger within the marine park. The abundance of targeted fish also fluctuated among years, indicating complex ecological dynamics. Conclusions Overall, ‘no take’ effects were strong and consistent across the study period. Implications The study has demonstrated the value of long-term monitoring to inform fishing activities and management strategies.