ORCID Profile
0000-0003-2207-2366
Current Organisation
Oregon State University
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Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.CUB.2016.04.022
Abstract: Marine no-take reserves, where fishing and other extractive activities are prohibited, have well-established conservation benefits [1], yet their impacts on fisheries remains contentious [2-4]. For fishery species, reserves are often implemented alongside more conventional harvest strategies, including catch and size limits [2, 5]. However, catch and fish abundances observed post-intervention are often attributed to reserves, without explicitly estimating the potential contribution of concurrent management interventions [2, 3, 6-9]. Here we test a metapopulation model against observed fishery [10] and population [11] data for an important coral reef fishery (coral trout Plectropomus spp.) in Australia's Great Barrier Reef Marine Park (GBRMP) to evaluate how the combined increase in reserve area [12] and reduction in fishing effort [13, 14] in 2004 influenced changes in fish stocks and the commercial fishery. We found that declines in catch, increases in catch rates, and increases in biomass since 2004 were substantially attributable to the integration of direct effort controls with the rezoning, rather than the rezoning alone. The combined management approach was estimated to have been more productive for fish and fisheries than if the rezoning had occurred alone and comparable to what would have been obtained with effort controls alone. Sensitivity analyses indicate that the direct effort controls prevented initial decreases in catch per unit effort that would have otherwise occurred with the rezoning. Our findings demonstrate that by concurrently restructuring the fishery, the conservation benefits of reserves were enhanced and the fishery cost of rezoning the reserve network was socialized, mitigating negative impacts on in idual fishers.
Publisher: Public Library of Science (PLoS)
Date: 11-05-2016
Publisher: Wiley
Date: 14-05-2019
DOI: 10.1002/EAP.1905
Abstract: Marine reserve networks are increasingly implemented to conserve bio ersity 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.
Publisher: Wiley
Date: 21-05-2022
DOI: 10.1111/ELE.14023
Abstract: Kelp habitat restoration is gaining traction as a management action to support recovery in areas affected by severe disturbances, thereby ensuring the sustainability of ecosystem services. Knowing when and where to restore is a major question. Using a single‐species population model, we consider how restoring inside marine protected areas (MPAs) might benefit coastal fish populations and fisheries. We found that MPAs can greatly enhance the population benefits of restoration but at a small cost to fishery yields. Generally, restoring inside MPAs had a better overall gains‐loss outcome, especially if the system is under high fishing pressure or severe habitat loss. However, restoring outside became preferable when predatory fish indirectly benefit kelp habitats. In either case, successful restoration actions may be difficult to detect in time‐series data due to complex transient dynamics. We provide context for setting management goals and social expectations for the ecosystem service implications of restoration in MPAs.
Publisher: Wiley
Date: 07-02-2022
DOI: 10.1002/EAP.2511
Abstract: Correctly identifying the effects of a human impact on a system is a persistent challenge in ecology, driven partly by the variable nature of natural systems. This is particularly true in many marine fishery species, which frequently experience large temporal fluctuations in recruitment that produce interannual variations in populations. This variability complicates efforts to maintain stocks at management targets or detect the effects of rebuilding efforts. We address this challenge in the context of no‐take marine reserves by exploring how variable larval recruitment could interact with the timing of reserve establishment and choice of s ling design to affect population dynamics and the detectability of reserve effects. To predict population changes in the years following a no‐take reserve implementation, we first tested for periodicity in larval recruitment in an important U.S. Pacific coast recreational fishery species (kelp bass, Paralabrax clathratus ) and then included that pattern in a population model. We also used this model to determine the detectability of population increases under alternative s ling approaches and minimum age s led. Kelp bass larval recruitment in the Channel Islands, California, peaked every about six (major) and about two (minor) years. Our model showed that establishing a reserve during a peak or trough enhanced or delayed, respectively, the post‐reserve population increases. However, establishing a reserve during a recruitment peak could obscure a failing reserve, that is, a reserve that is unable to secure longer‐term metapopulation persistence. Recruitment peaks and troughs also interacted with s ling design to affect the detectability of reserve effects. Designs that compared inside‐outside were the most robust to variable recruitment, but failed to capture whether the reserve has improved metapopulation growth. Designs that included a time element (e.g., before‐after) are more suited to assessing reserve effectiveness, but were sensitive to recruitment variation and detectability can change year‐to‐year. Notably, detectability did not always increase monotonically with reserve age the optimal time for detectability depended on the minimum age of organisms s led and was greatest when the cohort of a major recruitment peak first appeared in the s ling. We encourage managers to account for variable recruitment when planning monitoring and assessment programs.
Publisher: Springer Science and Business Media LLC
Date: 21-12-2012
Publisher: Wiley
Date: 04-2016
DOI: 10.1890/15-0348
Abstract: 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.
No related grants have been discovered for Jess K Hopf.