Implications of Urbanization for Artisanal Parrotfish Fisheries in the Western Solomon Islands

Abstract: Increasing migration into urbanized centers in the Solomon Islands poses a great threat to adjacent coral reef fisheries because of negative effects on the fisheries and because it further erodes customary management systems. Parrotfish fisheries are of particular importance because the feeding habits of parrotfish (scrape and excavate coral) are thought to be critical to the resilience of coral reefs and to maintaining coral reef health within marine protected areas. We investigated the ecological impact of localized subsistence and artisanal fishing pressure on parrotfish fisheries in Gizo Town, Western Solomon Islands, by analyzing the density and size distribution of parrotfish with an underwater visual census (UVC), recall diary (i.e., interviews with fishers), and creel surveys to independently assess changes in abundance and catch‐per‐unit‐effort (CPUE) over 2 years. We then compared parrotfish data from Gizo Town with equivalent data from sites open to and closed to fishing in Kida and Nusa Hope villages, which have different customary management regimes. Results indicated a gradient of customary management effectiveness. Parrotfish abundance was greater in customary management areas closed to fishing, especially with regard to larger fish sizes, than in areas open to fishing. The decline in parrotfish abundance from 2004 to 2005 in Gizo was roughly the same magnitude as the difference in abundance decline between inside and outside customary management marine reserves. Our results highlight how weak forms of customary management can result in the rapid decline of vulnerable fisheries around urbanized regions, and we present examples in which working customary management systems (Kinda and Nusa Hope) can positively affect the conservation of parrotfish—and reef fisheries in general—in the highly biodiverse Coral Triangle region.     

Effects of Human Population Density and Proximity to Markets on Coral Reef Fishes Vulnerable to Extinction by Fishing

Coral reef fisheries are crucial to the livelihoods of tens of millions of people; yet, widespread habitat degradation and unsustainable fishing are causing severe depletion of stocks of reef fish. Understanding how social and economic factors, such as human population density, access to external markets, and modernization interact with fishing and habitat degradation to affect fish stocks is vital to sustainable management of coral reef fisheries. We used fish survey data, national social and economic data, and path analyses to assess whether these factors explain variation in biomass of coral reef fishes among 25 sites in Solomon Islands. We categorized fishes into 3 groups on the basis of life‐history characteristics associated with vulnerability to extinction by fishing (high, medium, and low vulnerability). The biomass of fish with low vulnerability was positively related to habitat condition. The biomass of fishes with high vulnerability was negatively related to fishing conducted with efficient gear. Use of efficient gear, in turn, was strongly and positively related to both population density and market proximity. This result suggests local population pressure and external markets have additive negative effects on vulnerable reef fish. Biomass of the fish of medium vulnerability was not explained by fishing intensity or habitat condition, which suggests these species may be relatively resilient to both habitat degradation and fishing. Efectos de la Densidad de Poblaciones Humanas y la Proximidad del Mercado sobre Peces de Arrecifes de Coral Vulnerables a la Extinción     

Fishing‐gear restrictions and biomass gains for coral reef fishes in marine protected areas

Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing‐gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no‐take, hook‐and‐line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no‐take zones) most benefited community‐ and family‐level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community‐level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing‐gear types that affect biomass of a diverse set of reef fish families.     

Comparison of Modern and Historical Fish Catches (AD 750–1400) to Inform Goals for Marine Protected Areas and Sustainable Fisheries

Abstract: We tested the unsustainable fishing hypothesis that species in assemblages of fish differ in relative abundance as a function of their size, growth rates, vagility, trophic level, and diet by comparing species composition in historical bone middens, modern fisheries, and areas closed to fishing. Historical data came from one of the earliest and most enduring Swahili coastal settlements (approximately AD 750–1400). Modern data came from fisheries near the archeological site and intensively harvested fishing grounds in southern Kenya. The areas we sampled that were closed to fishing (closures) were small (<28 km²) and permanent. The midden data indicated changes in the fish assemblage that are consistent with a weak expansion of fishing intensity and the unsustainable fishing hypothesis. Fishes represented in the early midden assemblages from AD 750 to 950 had longer life spans, older age at maturity, and longer generation times than fish assemblages after AD 950, when the abundance of species with longer maximum body lengths increased. Changes in fish life histories during the historical period were, however, one‐third smaller than differences between the historical and modern assemblages. Fishes in the modern assemblage had smaller mean body sizes, higher growth and mortality rates, a higher proportion of microinvertivores, omnivores, and herbivores, and higher rates of food consumption, whereas the historical assemblage had a greater proportion of piscivores and macroinvertivores. Differences in fish life histories between modern closures and modern fishing grounds were also small, but the life histories of fishes in modern closures were more similar to those in the midden before AD 950 because they had longer life spans, older age at maturity, and a higher proportion of piscivores and macroinvertivores than the modern fisheries. Modern closures and historical fish assemblages were considerably different, although both contained species with longer life spans.     

Effects of Road Mortality and Mitigation Measures on Amphibian Populations

Road mortality is a widely recognized but rarely quantified threat to the viability of amphibian populations. The global extent of the problem is substantial and factors affecting the number of animals killed on highways include life‐history traits and landscape features. Secondary effects include genetic isolation due to roads acting as barriers to migration. Long‐term effects of roads on population dynamics are often severe and mitigation methods include volunteer rescues and under‐road tunnels. Despite the development of methods that reduce road kill in specific locations, especially under‐road tunnels and culverts, there is scant evidence that such measures will protect populations over the long term. There also seems little likelihood that funding will be forthcoming to ameliorate the problem at the scale necessary to prevent further population declines. Efectos de la Mortalidad en Carreteras y Medidas de Mitigación en Poblaciones de Anfibios Beebee     

Accuracy of Short‐Term Demographic Data in Projecting Long‐Term Fate of Populations

Short‐term surveys are useful in conservation of species if they can be used to reliably predict the long‐term fate of populations. However, statistical evaluations of reliability are rare. We studied how well short‐term demographic data (1999–2002) of tartar catchfly (Silene tatarica), a perennial riparian plant, projected the fate and growth of 23 populations of this species up to the year 2010. Surveyed populations occurred along a river with natural flood dynamics and along a regulated river. Riparian plant populations are affected by flooding, which maintains unvegetated shores, while forest succession proceeds in areas with little flooding. Flooding is less severe along the regulated river, and vegetation overgrowth reduces abundance of tartar catchfly on unvegetated shores. We built matrix models to calculate population growth rates and estimated times to population extinction in natural and in regulated rivers, 13 and 10 populations, respectively. Models predicted population survival well (model predictions matched observed survival in 91% of populations) and accurately predicted abundance increases and decreases in 65% of populations. The observed and projected population growth rates differed significantly in all but 3 populations. In most cases, the model overestimated population growth. Model predictions did not improve when data from more years were used (1999–2006). In the regulated river, the poorest model predictions occurred in areas where cover of other plant species changed the fastest. Although vegetation cover increased in most populations, it decreased in 4 populations along the natural river. Our results highlight the need to combine disturbance and succession dynamics in demographic models and the importance of habitat management for species survival along regulated rivers. Precisión de Datos Demográficos de Corto Plazo en la Proyección del Destino de Poblaciones a Largo Plazo     

Incorporating Surrogate Species and Seascape Connectivity to Improve Marine Conservation Outcomes

Conservation focuses on maintaining biodiversity and ecosystem functioning, but gaps in our knowledge of species biology and ecological processes often impede progress. For this reason, focal species and habitats are used as surrogates for multispecies conservation, but species‐based approaches are not widely adopted in marine ecosystems. Reserves in the Solomon Islands were designed on the basis of local ecological knowledge to conserve bumphead parrotfish (Bolbometopon muricatum) and to protect food security and ecosystem functioning. Bumphead parrotfish are an iconic threatened species and may be a useful surrogate for multispecies conservation. They move across tropical seascapes throughout their life history, in a pattern of habitat use that is shared with many other species. We examined their value as a conservation surrogate and assessed the importance of seascape connectivity (i.e., the physical connectedness of patches in the seascape) among reefs, mangroves, and seagrass to marine reserve performance. Reserves were designed for bumphead parrotfish, but also enhanced the abundance of other species. Integration of local ecological knowledge and seascape connectivity enhanced the abundance of 17 other harvested fish species in local reserves. This result has important implications for ecosystem functioning and local villagers because many of these species perform important ecological processes and provide the foundation for extensive subsistence fisheries. Our findings suggest greater success in maintaining and restoring marine ecosystems may be achieved when they are managed to conserve surrogate species and preserve functional seascape connections. Incorporación de Especies Sustitutas y de Conectividad Marina para Mejorar los Resultados de Conservación     

Ability of Matrix Models to Explain the Past and Predict the Future of Plant Populations

Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage‐based matrix models with demographic data from individually marked plants and determined how well these models forecast population sizes observed at least 5 years into the future. Simple demographic models forecasted population dynamics poorly; only 40% of observed population sizes fell within our forecasts’ 95% confidence limits. However, these models explained population dynamics during the years in which data were collected; observed changes in population size during the data‐collection period were strongly positively correlated with population growth rate. Thus, these models are at least a sound way to quantify population status. Poor forecasts were not associated with the number of individual plants or years of data. We tested whether vital rates were density dependent and found both positive and negative density dependence. However, density dependence was not associated with forecast error. Forecast error was significantly associated with environmental differences between the data collection and forecast periods. To forecast population fates, more detailed models, such as those that project how environments are likely to change and how these changes will affect population dynamics, may be needed. Such detailed models are not always feasible. Thus, it may be wiser to make risk‐averse decisions than to expect precise forecasts from models. Habilidad de los Modelos Matriciales para Explicar el Pasado y Predecir el Futuro de las Poblaciones de Plantas     

Drivers of Seabird Population Recovery on New Zealand Islands after Predator Eradication

Eradication of introduced mammalian predators from islands has become increasingly common, with over 800 successful projects around the world. Historically, introduced predators extirpated or reduced the size of many seabird populations, changing the dynamics of entire island ecosystems. Although the primary outcome of many eradication projects is the restoration of affected seabird populations, natural population responses are rarely documented and mechanisms are poorly understood. We used a generic model of seabird colony growth to identify key predictor variables relevant to recovery or recolonization. We used generalized linear mixed models to test the importance of these variables in driving seabird population responses after predator eradication on islands around New Zealand. The most influential variable affecting recolonization of seabirds around New Zealand was the distance to a source population, with few cases of recolonization without a source population ≤25 km away. Colony growth was most affected by metapopulation status; there was little colony growth in species with a declining status. These characteristics may facilitate the prioritization of newly predator‐free islands for active management. Although we found some evidence documenting natural recovery, generally this topic was understudied. Our results suggest that in order to guide management strategies, more effort should be allocated to monitoring wildlife response after eradication. Conductores de la Recuperación de Poblaciones de Aves Marinas en Islas de Nueva Zelanda después de la Erradicación de Depredadores     

Simulating Retention of Rare Alleles in Small Populations to Assess Management Options for Species with Different Life Histories

Preserving allelic diversity is important because it provides the capacity for adaptation and thus enables long‐term population viability. Allele retention is difficult to predict in animals with overlapping generations, so we used a new computer model to simulate retention of rare alleles in small populations of 3 species with contrasting life‐history traits: North Island Brown Kiwi (Apteryx mantelli; monogamous, long‐lived), North Island Robins (Petroica longipes; monogamous, short‐lived), and red deer (Cervus elaphus; polygynous, moderate lifespan). We simulated closed populations under various demographic scenarios and assessed the amounts of artificial immigration needed to achieve a goal of retaining 90% of selectively neutral rare alleles (frequency in the source population = 0.05) after 10 generations. The number of immigrants per generation required to meet the genetic goal ranged from 11 to 30, and there were key similarities and differences among species. None of the species met the genetic goal without immigration, and red deer lost the most allelic diversity due to reproductive skew among polygynous males. However, red deer required only a moderate rate of immigration relative to the other species to meet the genetic goal because nonterritorial breeders had a high turnover. Conversely, North Island Brown Kiwi needed the most immigration because the long lifespan of locally produced territorial breeders prevented a large proportion of immigrants from recruiting. In all species, the amount of immigration needed generally decreased with an increase in carrying capacity, survival, or reproductive output and increased as individual variation in reproductive success increased, indicating the importance of accurately quantifying these parameters to predict the effects of management. Overall, retaining rare alleles in a small, isolated population requires substantial investment of management effort. Use of simulations to explore strategies optimized for the populations in question will help maximize the value of this effort. Simulación de la Retención de Alelos Raros en Poblaciones Pequeñas para Evaluar Opciones de Manejo para Especies con Historias de Vida Diferentes     

Effectiveness of Predator Removal for Enhancing Bird Populations

Abstract: Predation pressure on vulnerable bird species has made predator control an important issue for international nature conservation. Predator removal by culling or translocation is controversial, expensive, and time‐consuming, and results are often temporary. Thus, it is important to assess its effectiveness from all available evidence. We used explicit systematic review methodology to determine the impact of predator removal on four measurable responses in birds: breeding performance (hatching success and fledging success) and population size (breeding and postbreeding). We used meta‐analysis to summarize results from 83 predator removal studies from six continents. We also investigated whether characteristics of the prey, predator species, location, and study methodology explained heterogeneity in effect sizes. Removing predators increased hatching success, fledging success, and breeding populations. Removing all predator species achieved a significantly larger increase in breeding population than removing only a subset. Postbreeding population size was not improved on islands, or overall, but did increase on mainlands. Heterogeneity in effect sizes for the four population parameters was not explained by whether predators were native or introduced; prey were declining, migratory, or game species; or by the study methodology. Effect sizes for fledging success were smaller for ground‐nesting birds than those that nest elsewhere, but the difference was not significant. We conclude that current evidence indicates that predator removal is an effective strategy for the conservation of vulnerable bird populations. Nevertheless, the ethical and practical problems associated with predator removal may lead managers to favor alternative, nonlethal solutions. Research is needed to provide and synthesize data to determine whether these are effective management practices for future policies on bird conservation.     

Evaluating Alternative Strategies for Minimizing Unintended Fitness Consequences of Cultured Individuals on Wild Populations

Artificial propagation strategies often incur selection in captivity that leads to traits that are maladaptive in the wild. For propagation programs focused on production rather than demographic contribution to wild populations, effects on wild populations can occur through unintentional escapement or the need to release individuals into natural environments for part of their life cycle. In this case, 2 alternative management strategies might reduce unintended fitness consequences on natural populations: (1) reduce selection in captivity as much as possible to reduce fitness load (keep them similar), or (2) breed a separate population to reduce captive‐wild interactions as much as possible (make them different). We quantitatively evaluate these 2 strategies with a coupled demographic–genetic model based on Pacific salmon hatcheries that incorporates a variety of relevant processes and dynamics: selection in the hatchery relative to the wild, assortative mating based on the trait under selection, and different life cycle arrangements in terms of hatchery release, density dependence, natural selection, and reproduction. Model results indicate that, if natural selection only occurs between reproduction and captive release, the similar strategy performs better. However, if natural selection occurs between captive release and reproduction, the different and similar strategies present viable alternatives to reducing unintended fitness consequences because of the greater opportunity to purge maladaptive individuals. In this case, the appropriate approach depends on the feasibility of each strategy and the demographic goal (e.g., increasing natural abundance, or ensuring that a high proportion of natural spawners are naturally produced). In addition, the fitness effects of hatchery release are much greater if hatchery release occurs before (vs. after) density‐dependent interactions. Given the logistical challenges to achieving both the similar and different strategies, evaluation of not just the preferred strategy but also the consequences of failing to achieve the desired target is critical. Evaluación de Estrategias Alternativas para Minimizar las Consecuencias No Inesperadas en la Adecuación de Individuos Criados en Cautiverio sobre Poblaciones Silvestres     

Shifting Baselines and The Extinction of The Caribbean Monk Seal

The recent extnction of the Caribbean monk seal Monachus tropicalis has been considered an example of a human‐caused extinction in the marine environment, and this species was considered a driver of the changes that have occurred in the structure of Caribbean coral reef ecosystems since colonial times. I searched archaeological records, historical data, and geographic names (used as a proxy of the presence of seals) and evaluated the use and quality of these data to conclude that since prehistoric times the Caribbean monk seal was always rare and vulnerable to human predation. This finding supports the hypothesis that in AD 1500, the Caribbean monk seal persisted as a small fragmented population in which individuals were confined to small keys, banks, or isolated islands in the Gulf of Mexico and the Caribbean Sea. This hypothesis is contrary to the assumption that the species was widespread and abundant historically. The theory that the main driver of monk seal extinction was harvesting for its oil for use in the sugar cane industry of Jamaica during the 18th century is based primarily on anecdotal information and is overemphasized in the literature. An analysis of reported human encounters with this species indicates monk seal harvest was an occasional activity, rather than an ongoing enterprise. Nevertheless, given the rarity of this species and its restricted distribution, even small levels of hunting or specimen collecting must have contributed to its extinction, which was confirmed in the mid‐20th century. Some sources had been overlooked or only partially reviewed, others misinterpreted, and a considerable amount of anecdotal information had been uncritically used. Critical examination of archaeological and historical records is required to infer accurate estimations of the historical abundance of a species. In reconstructing the past to address the shifting baseline syndrome, it is important to avoid selecting evidence to confirm modern prejudices. Puntos de Referencia Cambiantes y la Extinción de la Foca Monje Caribeña     

Occupancy Patterns of Regionally Declining Grassland Sparrow Populations in a Forested Pennsylvania Landscape

Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single‐season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter–area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m². Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter–area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland ( = 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the foreseeable future. Patrones de Ocupación de Poblaciones Regionalmente Declinantes de Gorriones de Pastizales en un Paisaje Boscoso de Pennsylvania     

Scale Mismatches,Conservation Planning,and the Value of Social‐Network Analyses

Many of the challenges conservation professionals face can be framed as scale mismatches. The problem of scale mismatch occurs when the planning for and implementation of conservation actions is at a scale that does not reflect the scale of the conservation problem. The challenges in conservation planning related to scale mismatch include ecosystem or ecological process transcendence of governance boundaries; limited availability of fine‐resolution data; lack of operational capacity for implementation; lack of understanding of social‐ecological system components; threats to ecological diversity that operate at diverse spatial and temporal scales; mismatch between funding and the long‐term nature of ecological processes; rate of action implementation that does not reflect the rate of change of the ecological system; lack of appropriate indicators for monitoring activities; and occurrence of ecological change at scales smaller or larger than the scale of implementation or monitoring. Not recognizing and accounting for these challenges when planning for conservation can result in actions that do not address the multiscale nature of conservation problems and that do not achieve conservation objectives. Social networks link organizations and individuals across space and time and determine the scale of conservation actions; thus, an understanding of the social networks associated with conservation planning will help determine the potential for implementing conservation actions at the required scales. Social‐network analyses can be used to explore whether these networks constrain or enable key social processes and how multiple scales of action are linked. Results of network analyses can be used to mitigate scale mismatches in assessing, planning, implementing, and monitoring conservation projects. Discordancia de Escalas, Planificación de la Conservación y el Valor del Análisis de Redes Sociales     

The Biogeography of Globally Threatened Seabirds and Island Conservation Opportunities

Seabirds are the most threatened group of marine animals; 29% of species are at some risk of extinction. Significant threats to seabirds occur on islands where they breed, but in many cases, effective island conservation can mitigate these threats. To guide island‐based seabird conservation actions, we identified all islands with extant or extirpated populations of the 98 globally threatened seabird species, as recognized on the International Union for Conservation of Nature Red List, and quantified the presence of threatening invasive species, protected areas, and human populations. We matched these results with island attributes to highlight feasible island conservation opportunities. We identified 1362 threatened breeding seabird populations on 968 islands. On 803 (83%) of these islands, we identified threatening invasive species (20%), incomplete protected area coverage (23%), or both (40%). Most islands with threatened seabirds are amenable to island‐wide conservation action because they are small (57% were <1 km²), uninhabited (74%), and occur in high‐ or middle‐income countries (96%). Collectively these attributes make islands with threatened seabirds a rare opportunity for effective conservation at scale. La Biogeografía de Aves Marinas Amenazadas Globalmente y las Oportunidades de Conservación en Islas     

Habitat and reef-fish assemblages of banks in the Northwestern Hawaiian Islands

The moderately deep terraces and banks of the Northwestern Hawaiian Islands (NWHI) were surveyed to describe their habitat and reef-fish assemblages. These tracts of bottom at 30–40 m comprise more than 4,500 km² of the regions reef area. The habitat was found to be dominated by algal meadows (65% cover of exposed bottom), with infrequent relief features. Annual monitoring of select stations for 4 years at Necker Bank indicated that the relative difference in algal abundance between stations persisted from year to year (at least in summer). Temperature records from year-long deployments of archival thermistors in high-cover (>70%) and low-cover (<30%) algal biotopes were indistinguishable, providing no explanation of the algal differences between stations. At all banks, Microdictyon was the primary alga, averaging 1.22 kg/m². In spite of the extensive standing primary production, and a historical lack of fishing, bank reef-fish populations were impoverished. Mean densities, sizes, and biomass of trophic groups were considerably less than values reported for NWHI reef shallows. An overall mean biomass was estimated at 22.5 g/m², which is a fifth of that reported for shallow reefs of the region. Fish biomass of all trophic groups was associated with the few sources of relief available on the banks. Apex predators (sharks, jacks, and snappers), common on all surveys (with a mean of five per station), were proposed to constrain fish populations to sparse sources of relief resulting in a skewed size structure of the two primary fish trophic components. Sizes of lower-level carnivores were tightly correlated with sources of relief whereas the size of herbivores were not, indicating that herbivores more often venture out and risk the exposed algal meadows. These bank summits are a rare example of a near pristine reef system with high benthic primary productivity and low fish biomass, and are a stark contrast to shallower coral-reef ecosystems of the NWHI.Communicated by P.W. Sammarco, Chauvin     

Impact of conservation areas on trophic interactions between apex predators and herbivores on coral reefs

Apex predators are declining at alarming rates due to exploitation by humans, but we have yet to fully discern the impacts of apex predator loss on ecosystem function. In a management context, it is critically important to clarify the role apex predators play in structuring populations of lower trophic levels. Thus, we examined the top‐down influence of reef sharks (an apex predator on coral reefs) and mesopredators on large‐bodied herbivores. We measured the abundance, size structure, and biomass of apex predators, mesopredators, and herbivores across fished, no‐take, and no‐entry management zones in the Great Barrier Reef Marine Park, Australia. Shark abundance and mesopredator size and biomass were higher in no‐entry zones than in fished and no‐take zones, which indicates the viability of strictly enforced human exclusion areas as tools for the conservation of predator communities. Changes in predator populations due to protection in no‐entry zones did not have a discernible influence on the density, size, or biomass of different functional groups of herbivorous fishes. The lack of a relationship between predators and herbivores suggests that top‐down forces may not play a strong role in regulating large‐bodied herbivorous coral reef fish populations. Given this inconsistency with traditional ecological theories of trophic cascades, trophic structures on coral reefs may need to be reassessed to enable the establishment of appropriate and effective management regimes. El Impacto de las Áreas de Conservación sobre las Interacciones Tróficas entre los Depredadores Dominantes y los Herbívoros en los Arrecifes de Coral     

Six Common Mistakes in Conservation Priority Setting

A vast number of prioritization schemes have been developed to help conservation navigate tough decisions about the allocation of finite resources. However, the application of quantitative approaches to setting priorities in conservation frequently includes mistakes that can undermine their authors’ intention to be more rigorous and scientific in the way priorities are established and resources allocated. Drawing on well‐established principles of decision science, we highlight 6 mistakes commonly associated with setting priorities for conservation: not acknowledging conservation plans are prioritizations; trying to solve an ill‐defined problem; not prioritizing actions; arbitrariness; hidden value judgments; and not acknowledging risk of failure. We explain these mistakes and offer a path to help conservation planners avoid making the same mistakes in future prioritizations. Seis Errores Comunes en la Definición de Prioridades de Conservación