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Well-managed and enforced no-take marine reserves generate important larval subsidies to neighboring habitats and thereby contribute to the long-term sustainability of fisheries. However, larval dispersal patterns are variable, which leads to temporal fluctuations in the contribution of a single reserve to the replenishment of local populations. Identifying management strategies that mitigate the uncertainty in larval supply will help ensure the stability of recruitment dynamics and minimize the volatility in fishery catches. Here, we use genetic parentage analysis to show extreme variability in both the dispersal patterns and recruitment contribution of four individual marine reserves across six discrete recruitment cohorts for coral grouper (Plectropomus maculatus) on the Great Barrier Reef. Together, however, the asynchronous contributions from multiple reserves create temporal stability in recruitment via a connectivity portfolio effect. This dampening effect reduces the variability in larval supply from individual reserves by a factor of 1.8, which effectively halves the uncertainty in the recruitment contribution of individual reserves. Thus, not only does the network of four marine reserves generate valuable larval subsidies to neighboring habitats, the aggregate effect of individual reserves mitigates temporal fluctuations in dispersal patterns and the replenishment of local populations. Our results indicate that small networks of marine reserves yield previously unrecognized stabilizing benefits that ensure a consistent larval supply to replenish exploited fish stocks. [ABSTRACT FROM AUTHOR]

Marine protected areas are increasingly being implemented to attain a variety of conservation and fisheries management objectives. Although rarely considered, protection of targeted species within these areas may also conserve behaviours (e.g. boldness) that are often the first removed by human exploitation. Here we examine fish behaviour in fished, no-take, and no-entry management zones for a highly targeted reef fish species (coral trout; Plectropomus leopardus ) on coral reefs in two regions of the Great Barrier Reef Marine Park, Australia. Using three behavioural metrics (flight-initiation distance, pre-flight behaviour, and escape trajectories), we demonstrate how protected areas, particularly no-entry zones, can effectively conserve naïve or bold behavioural traits in fish populations. Flight-initiation distance was consistently highest in fished zones, but the effects of protection afforded by no-take and no-entry zones varied by study region. Flight-initiation distance was consistently higher for fish above the minimum legal retention size limit, except in no-entry zones of the southern region. This indicates that no-entry zones may be maintaining near-natural, pre-exploitation behaviour, which could have considerable implications for the genetic and social structures of a highly valuable commercial species. Conservation and fisheries management would therefore benefit from an increased understanding of how fish behaviour can influence population structures, and how these populations may be influenced by fishing and other human interactions. [ABSTRACT FROM AUTHOR]

Marine reserves are often established in areas that support fisheries. Larval export from reserves is argued to help compensate for the loss of fishable habitat; however, previous modeling studies have focused on long-term equilibrium outcomes. We examined the transient consequences of reserve establishment for fished metapopulations, considering both a well-mixed larval pool and a spatially explicit model based on a coral trout ( Plectropomus spp.) metapopulation. When fishing pressure was reallocated relative to the area protected, yields decreased initially, then recovered, and ultimately exceeded pre-reserve levels. However, recovery time was on the order of several years to decades. If fishing pressure intensified to maintain pre-reserve yields, reserves were sometimes unable to support the increased mortality and the metapopulation collapsed. This was more likely when reserves were small, or located peripherally within the metapopulation. Overall, reserves can achieve positive conservation and fishery benefits, but fisheries management complementary to reserve implementation is essential. [ABSTRACT FROM AUTHOR]

The development of parentage analysis to track the dispersal of juvenile offspring has given us unprecedented insight into the population dynamics of coral reef fishes. These tools now have the potential to inform fisheries management and species conservation, particularly for small fragmented populations under threat from exploitation and disturbance. In this study, we resolve patterns of larval dispersal for a population of the anemonefish Amphiprion melanopus in the Keppel Islands (southern Great Barrier Reef). Habitat loss and fishing appear to have impacted this population and a network of no-take marine reserves currently protects 75% of the potential breeders. Using parentage analysis, we estimate that 21% of recruitment in the island group was generated locally and that breeding adults living in reserves were responsible for 79% (31 of 39) of these of locally produced juveniles. Overall, the network of reserves was fully connected via larval dispersal; however, one reserve was identified as a critical source of larvae for the island group. The population in the Keppel Islands also appears to be well-connected to other source populations at least 60 km away, given that 79% (145 of 184) of the juveniles sampled remained unassigned in the parentage analysis. We estimated the effective size of the A. melanopus metapopulation to be 745 (582-993 95% CI) and recommend continued monitoring of its genetic status. Maintaining connectivity with populations beyond the Keppel Islands and recovery of local recruitment habitat, potentially through active restoration of host anemone populations, will be important for its long-term persistence. [ABSTRACT FROM AUTHOR]

Marine reserve networks are increasingly implemented to conserve biodiversity and enhance the persistence and resilience of exploited species and ecosystems. However, the efficacy of marine reserve networks in frequently disturbed systems, such as coral reefs, has rarely been evaluated. Here we analyze a well‐mixed larval pool model and a spatially explicit model based on a well‐documented coral trout (Plectropomus spp.) metapopulation in the Great Barrier Reef Marine Park, Australia, to determine the effects of marine reserve coverage and placement (in relation to larval connectivity and disturbance heterogeneity) on the temporal stability of fisheries yields and population biomass in environmentally disturbed systems. We show that marine reserves can contribute to stabilizing fishery yield while increasing metapopulation persistence, irrespective of whether reserves enhance or diminish average fishery yields. However, reserve placement and the level of larval connectivity among subpopulations were important factors affecting the stability and sustainability of fisheries and fish metapopulations. Protecting a mix of disturbed and non‐disturbed reefs, rather than focusing on the least‐disturbed habitats, was the most consistently beneficial approach across a range of dispersal and reserve coverage scenarios. Placing reserves only in non‐disturbed areas was the most beneficial for biomass enhancement, but had variable results for fisheries and could potentially destabilize yields in systems with well‐mixed larval or those that are moderately fished. We also found that focusing protection on highly disturbed areas could actually increase variability in yields and biomass, especially when degraded reef reserves were distant and poorly connected to the meta‐population. Our findings have implications for the design and implementation of reserve networks in the presence of stochastic, patchy environmental disturbances. [ABSTRACT FROM AUTHOR]

Highlights: [•] Densities of targeted fishes were higher at sites with recruitment hotspots. [•] Population recovery was enhanced in reserves that contained recruitment hotspots. [•] Reserves primarily protected fishes above the minimum legal size. [Copyright &y& Elsevier]