Background/Aims:
Tasmanian temperate reef environments are under mounting pressures from anthropogenic climate change, invasive species, and coastal development, all of which threaten to alter the structure of reef fish communities. Moreover, the effects of recreational fishing pressure in the area are poorly understood, with current stock assessment methods likely failing to capture the true levels of exploitation. The Tasman Peninsula in south-east Tasmania is a hotspot for recreational and commercial fishing and provides significant cultural, ecological, and commercial value to the region. The state’s recreational sector is estimated to be worth $270 million annually, with up to 50% of catch coming from this heavily fished region. Given the current environmental challenges, there is an ever-growing need to better characterise and monitor these reef systems. This study investigated the spatial and temporal trends in commercially targeted reef fish across the Tasman peninsula.
Methods:
Over the summer and winter months of 2024 and 2025, 150 stereo-BRUVS were deployed across three depths (5-10m, 30-40m and 50-60m), and five sites. Length and abundance data was modelled using GAM’s to assess for spatial and temporal patterns.
Results:
We found a significant difference in the fish assemblage structure between winter and summer months, characterised by greater abundances of range extending species such as Nemadactylus douglasii (Grey Morwong). Fish community composition also varied across depth gradients, with greater abundances and species richness observed in mid and deep sites compared to shallow sites. Shallow sites were dominated by species in the family Labridae (Wrasses), while mid and deep sites were characterised by species such as Nemadactylus macropterus (Jackass Morwong) and Heliocolenus percoides (Ocean Perch).
Conclusion:
These results provide valuable information to enhance our understanding of rocky reef fish communities, offering critical insights to the population dynamics of key data-poor fishery species. Overall, this will contribute to improving management approaches and assist to developing novel fisheries-independent monitoring methods in the region. These may be able to supplement and improve current annual stock assessments that are currently based only on commercial fisheries-dependent data.