Assessing the population‐level conservation effects of marine protected areas

Ovando, Daniel; Caselle, Jennifer E.; Costello, Christopher; Deschênes, Olivier; Gaines, Steven D.; Hilborn, Ray; Liu, Owen

doi:10.1111/cobi.13782

Cited by 37 publications

(26 citation statements)

References 47 publications

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“…As with all protected areas, the effective use of reserves as management tools (e.g., adaptive management) relies on assessing whether reserves are achieving these goals. If reserves are functioning as planned, then the abundance and biomass densities of exploited species are expected to increase within the protected areas and, as subsides are exported from reserve populations, densities are expected to eventually build up across the metapopulation (Hopf et al, 2016b; Moffitt et al, 2013; Pelc et al, 2010), although this effect may be difficult to empirically demonstrate (Ovando et al, 2021). Here we use the term metapopulation to refer to a collection of connected (sub)populations, each of which may exhibit different demographics (i.e., fished and reserve (sub)populations that have different rates of adults mortality due to fishing).…”

Section: Introductionmentioning

confidence: 99%

Recruitment variability and sampling design interact to influence the detectability of protected area effects

Hopf

Caselle

White

2022

Ecological Applications

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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 sampling 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 sampling approaches and minimum age sampled. 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 sampling 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 sampled and was greatest when the cohort of a major recruitment peak first appeared in the sampling. We encourage managers to account for variable recruitment when planning monitoring and assessment programs.

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Section: Introductionmentioning

confidence: 99%

Recruitment variability and sampling design interact to influence the detectability of protected area effects

Hopf

Caselle

White

2022

Ecological Applications

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“…The absence of a clear MPA effect is not necessarily indicative of failure of the closure as a management strategy (Ovando et al, 2021). At present (2021), the SWMPA has been closed to bottom fishing for over 12 years; while this may be long enough for a noticeable effect to appear in the age structure of species like red porgy, it is a fraction of the maximum longevity of some of the species targeted for protection.…”

Section: Discussionmentioning

confidence: 99%

Evaluating the Effects of a Deep-Water Marine Protected Area a Decade After Closure: A Multifaceted Approach Reveals Equivocal Benefits to Reef Fish Populations

et al. 2021

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Marine protected areas (MPAs) are increasingly used to rebuild fish populations. In 2009, eight MPAs were designated off the southeast United States with the goal of rebuilding populations of long-lived deep-water reef fishes. We tested whether reef fish within the largest of these MPAs, the Snowy Wreck Marine Protected Area (SWMPA), have increased in size and abundance relative to a nearby control area and compared to pre-closure. Hurdle models fitted through Bayesian inference on echosounder data collected in 2007–2009 and 2018–2020 yielded no evidence of an MPA effect. Comparisons of catch-per-unit-effort (CPUE) of all reef fishes yielded similar null results. However, CPUE of reef species with formal stock assessments increased 47% in the SWMPA and decreased 50% in the control area. We found significant increases in mean length of red porgy (Pagrus pagrus) inside the SWMPA but not in the control area. We also found community composition changes, including shifts away from groupers (Serranidae; Epinephelinae) and toward snappers (Lutjanidae) and tilefish (Malacanthidae) in both areas, though we did not detect an MPA effect with this analysis. Our equivocal results indicate that more time and stricter enforcement may be necessary before more biological effects of the SWMPA can be detected.

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“…MPAs that successfully protect spawning aggregations can significantly benefit surrounding fisheries through the export of eggs and larvae outside of the protected area (Beets and Friedlander, 1999;Erisman et al, 2015). However, region-wide fisheries benefits of MPAs may be difficult to detect empirically, even when they occur (Ovando et al, 2021).…”

Section: Fisheries Sectormentioning

confidence: 99%

A Scientific Synthesis of Marine Protected Areas in the United States: Status and Recommendations

et al. 2022

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Marine protected areas (MPAs) are a key tool for achieving goals for biodiversity conservation and human well-being, including improving climate resilience and equitable access to nature. At a national level, they are central components in the U.S. commitment to conserve at least 30% of U.S. waters by 2030. By definition, the primary goal of an MPA is the long-term conservation of nature; however, not all MPAs provide the same ecological and social benefits. A U.S. system of MPAs that is equitable, well-managed, representative and connected, and includes areas at a level of protection that can deliver desired outcomes is best positioned to support national goals. We used a new MPA framework, The MPA Guide, to assess the level of protection and stage of establishment of the 50 largest U.S. MPAs, which make up 99.7% of the total U.S. MPA area (3.19 million km2). Over 96% of this area, including 99% of that which is fully or highly protected against extractive or destructive human activities, is in the central Pacific ocean. Total MPA area in other regions is sparse – only 1.9% of the U.S. ocean excluding the central Pacific is protected in any kind of MPA (120,976 km2). Over three quarters of the non-central Pacific MPA area is lightly or minimally protected against extractive or destructive human activities. These results highlight an urgent need to improve the quality, quantity, and representativeness of MPA protection in U.S. waters to bring benefits to human and marine communities. We identify and review the state of the science, including focal areas for achieving desired MPA outcomes and lessons learned from places where sound ecological and social design principles come together in MPAs that are set up to achieve national goals for equity, climate resilience, and biodiversity conservation. We recommend key opportunities for action specific to the U.S. context, including increasing funding, research, equity, and protection level for new and existing U.S. MPAs.

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Assessing the population‐level conservation effects of marine protected areas

Abstract: Population-level conservation effects of marine protected areas are likely to be extremely challenging to measure and detect.

Cited by 37 publications

References 47 publications

Recruitment variability and sampling design interact to influence the detectability of protected area effects

Recruitment variability and sampling design interact to influence the detectability of protected area effects

Evaluating the Effects of a Deep-Water Marine Protected Area a Decade After Closure: A Multifaceted Approach Reveals Equivocal Benefits to Reef Fish Populations

A Scientific Synthesis of Marine Protected Areas in the United States: Status and Recommendations

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