Abstract
Marine Protected Areas (MPAs) are known to contribute towards the conservation of marine biodiversity, particularly targeted fishery species. Snapper Chrysophrys auratus are an important recreational and commercial fish species in New South Wales (NSW), Australia, and despite fishery management for this species, they are considered ‘growth overfished’ in this region. To assess how C. auratus respond to the implementation of an MPA with several no-take and partially protected areas in temperate NSW, we monitored their populations over a decade (2006-2017) using baited remote underwater video systems (BRUVs). Surveys were conducted in the Port Stephens-Great Lakes Marine Park with BRUVs deployed on rocky reefs in depths of 20 – 50 m. Long term seasonal sampling (winter vs summer) was undertaken at two locations (Broughton and Fingal Island), and changes in C. auratus abundance prior to, and eight years after zoning implementation, were assessed between these two locations. In total, we sampled five no-take areas within the marine park and five comparative nearby partially protected fished areas and three sites located outside the marine park boundaries. The most pronounced changes in abundance and size structure for C. auratus were observed in the Broughton Island no-take area where numbers increased almost 3-fold (2.91 times) over 8 years of protection. Relative abundance showed seasonal variation at two locations, and we consistently recorded increasing abundance within no-take areas at Broughton and Fingal Island compared to nearby sites open to fishing. Surveys across the five no-take areas found a significant increase in the abundance of C. auratus, whilst the five partially-protected locations in the marine park still recorded higher abundances than sites outside the marine park. In addition, length measurements from stereo-BRUVS indicated that C. auratus were significantly larger in no-take areas compared to partially-protected areas in the marine park and sites outside the marine park. This study demonstrates how the implementation of the marine park and the protection afforded by no-take and partially-protected areas provides refuge for this important fishery targeted species.
Highlights
The establishment of Marine Protected Areas (MPAs) to protect and conserve marine biodiversity is a well-established practice worldwide (Halpern, 2003; Sciberras et al, 2015)
There was a significant difference in the relative abundance of C. auratus across zoning (β = 0.57, p < 0.01) with a predicted 1.78 (1.40–2.25 95% CI) times more C. auratus within notake areas when compared with Partially Protected Areas (PPAs)
The model suggests that there is no significant difference in relative abundance of C. auratus between the two locations (β = −0.01, p = 0.23) with 0.90 (0.76–95% CI) times the number of C. auratus estimated for Fingal Island when compared with Broughton Island
Summary
The establishment of Marine Protected Areas (MPAs) to protect and conserve marine biodiversity is a well-established practice worldwide (Halpern, 2003; Sciberras et al, 2015). No-take areas within MPAs often show an increase in abundance and size of harvested species and measurable changes in the trophic structure (Halpern et al, 2010; Sciberras et al, 2013; Edgar et al, 2017), the size of the effect is strongly influenced by factors such as reserve size, location and age, levels of compliance, life-history characteristics, and population status of harvest species (Claudet et al, 2008; Edgar et al, 2014; Malcolm et al, 2016) Due to these responses, MPAs are increasingly recognized as one tool that can contribute to managing some pressures associated with fishing at spatial scales related to the size of the MPA and associated zones (Gaines et al, 2010; Sciberras et al, 2015; Campbell et al, 2017). The extent of spill-over from no-take areas is highly variable and untested for most species (Buxton et al, 2014), several studies have demonstrated that MPAs can result in higher fish abundance in surrounding areas (Kerwath et al, 2013; Sackett et al, 2017) and contribute to larval replenishment to surrounding populations (Harrison et al, 2012; Peters et al, 2017)
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