Distribution Of Predators Research Articles

Human presence shifts the landscape of fear for a free-living mammal.

Humans may play a key role in providing small prey mammals spatial and temporal refuge from predators, but few studies have captured the heterogeneity of these effects across space and time. Global COVID-19 lockdown restrictions offered a unique opportunity to investigate how a sudden change in human presence in a semi-urban park impacted wildlife. Here, we quantify how changes in the spatial distributions of humans and natural predators influenced the landscape of fear for the California ground squirrel (Otospermophilus beecheyi) in a COVID-19 pandemic (2020) and non-COVID (2019) year. We used a structural equation modeling approach to explore the direct and indirect effects of human presence, predator presence, and habitat features on foraging that reflected fear responses (e.g., giving-up densities [GUDs], number of foragers, and average food intake rate while at food patches). In 2019, humans and dogs had moderate effects on GUDs; squirrels were less fearful (lower GUDs) in areas frequently visited by humans and dogs, but the effects of raptors were weak. In contrast, in 2020, the effects of humans and dogs on GUDs were weak; squirrels were more fearful of high raptor activity, open sky, and ground cover. In both years, squirrels farthest from refuge were the most risk-averse. Overall, our analyses revealed an increase in perceived risk from natural predators in 2020 associated with a change in the concentration of human presence. Thus, risk-sensitive foraging was dynamic across space and time, depending on a complex interplay among human and dog activity, natural predators, and microhabitat features. Our findings elucidate the myriad ways humans directly and indirectly influence animal perception of safety and danger.

Distribution, composition and impact of environmental factors on benthic macroinvertebrates functional feeding groups and ecosystem attributes in river Yaah (East Lekie)

From July 2022 to May 2023, a study was carried out in the Lékié division (Center region) and its objective was to evaluate the composition and distribution of benthic macroinvertebrates functional feeding groups in relation to the characteristics of environmental factors and determine the ecosystem attributes of the Yaah watercourse. For that, in three sampling stations, the collection of water samples for analysis and benthic macroinvertebrates were carried out according to standard methods. The grouping of benthic macroinvertebrates into functional feeding groups was done thanks to the keys and appropriate works. A total of 730 benthic macroinvertebrates belonging to 38 families were identified and the families of Belostomidae (11.51%) and Libellulidae (10.96%) were the most dominant. The 38 families of benthic macroinvertebrates identified were grouped into 5 trophic functional groups, predators (63.29%) and Shredders (22.19%) were largely predominant. The distribution of collectors varied from YA 1 to YA 3. The abundance relative of Shredders decreased from upstream to downstream while that of filters increased earlier and these variations were consistent with the River Continuum Concept. The electrical conductivity was influenced positively the distribution of scrapers and gathering collectors while the suspended solids negatively influenced the distribution of shredders and positively the distribution of predators. The watercourses sampled were heterotrophic, conducive to the development of shredders and dominated by Coarse Particulate Organic Matter and predators.

Hybrid control for the prey in a spatial prey-predator model with cooperative hunting and fear effect time lag

In the ecosystem, the chase of the predator with cooperation contributes to fear psychology in the prey, resulting in behavioral changes such as a decrease in the birth rate. We construct a spatially diffusive model with delay to investigate the combined perturbation of these factors. Initially, we establish the existence of positive solutions and examine the stability of steady-state solutions under varying conditions. The bifurcation dynamics of the positive solutions have been analyzed. Turing instability, arising from the random diffusion of the species, generates spatially irregular patterns characterized by patchy distribution of prey and predators in the spatial domain. Hopf bifurcation, resulting from the diffusive rate and delay, contributes to spatially periodic solutions where the number of species will spatially oscillate. The combined influence of diffusion and delay results in the emergence of Turing and Hopf bifurcation phenomena. In this case, the combined effect amplifies the spatially heterogeneous distribution of prey and predator. Our results reveal the heterogeneous behaviors of prey and predator under the coupled influence of cooperation hunting and fear effects. In this paper, we will also study a hybrid control scheme for controlling the generations of Turing patterns and Hopf bifurcation. Our theoretical results and numerical simulations demonstrate that the control scheme can mitigate the negative influence of combined factors and promote the species' stability.

Predicting the impact of climate change on the potential geographical distribution and growth index of mirid predator, Nesidiocoris tenuis (reuter) (Heteroptera: Miridae) using CLIMEX

Predicting the impact of climate change on the potential geographical distribution and growth index of mirid predator, Nesidiocoris tenuis (reuter) (Heteroptera: Miridae) using CLIMEX

Gut microbiota dynamics of adult and sub‐adult sika deer during reintroduction

AbstractPrey populations significantly influence the distribution of top predators. The sika deer (Cervus nippon), a key prey species for the Amur tiger in Northeast China, plays a critical role in the recovery and dispersal of Amur tiger populations. Reintroduction is a pivotal strategy for restoring prey populations, but it presents challenges, especially in terms of adaptation to the natural environment during the natural training process before animals are released. In this study, we sampled six adult and six sub‐adult sika deer and employed high‐throughput sequencing of the 16S ribosomal RNA gene to investigate changes in gut microbial diversity, composition, and function during natural training. The results showed that adult sika deer had higher gut microbiota diversity compared to sub‐adults. However, as natural training progressed, the gut microbial diversity in sub‐adults approached that of adults. Additionally, beneficial, fiber‐digesting bacteria associated with adaptation to the natural environment tended to increase during nature training in both adult and sub‐adult sika deer, while pathogenic bacteria tended to decrease. We also compared the metabolic function of the gut microbiota in adult and sub‐adult sika deer, which showed that the carbohydrate metabolic function of both adults and sub‐adults decreased significantly with natural training, declining more rapidly in sub‐adults. Conversely, the lipid metabolic function in sub‐adults increased significantly with natural training. Overall, a period of nature training is necessary before reintroducing animals to their natural habitats, and sub‐adult sika deer, in particular, exhibit greater adaptability to environmental changes as reflected by their gut microbiota dynamics. These findings offer valuable insights for the reintroduction of sika deer and other ungulates. We recommend incorporating natural training in reintroduction programs and prioritizing sub‐adult animals for reintroduction.

Linking landscape structure, floral resource distribution, pollen use and movement distances of a generalist predator

Abstract Understanding the habitat use and movement patterns of natural enemies in agricultural landscapes is essential for enhancing biological pest control. Since many natural enemies rely on floral resources, the distribution of these resources in combination with movement behaviour likely influence biological control in field crops. Nevertheless, few studies have assessed natural enemy movement at the landscape scale. Here we estimated minimal movement distances of the green lacewing Chrysoperla carnea based on consumed pollen and the spatial distribution of the respective plant species in 24 agricultural landscapes (500 m radius). Lacewings were sampled using sticky traps in the centre of each landscape, and the consumed pollen were identified. The location of the most important pollen‐providing plants was mapped in each landscape. Distances to potential sources of pollen consumed by 346 lacewings were used to derive minimal movement distances. Lacewings consumed mostly pollen from insect‐pollinated plants that were present within 500 m from the sampling location. The distance to the nearest source of consumed pollen exceeded 200 m in 31% of lacewing individuals, demonstrating the relevance of the landscape scale to understand their population dynamics. Distances were shorter to insect‐pollinated than to wind‐pollinated plants, and shorter early than late in the season. Mean and median distances to pollen sources were negatively associated to flower availability and edge density in the landscape, but this was not the case for minimal distances. Synthesis and applications. Our findings suggest that the spatial distribution of flowering wild plants can inform movement patterns of lacewings and other flower‐visiting insects in agricultural landscapes. In addition, the location of floral resources in the landscape is important for its capacity to sustain natural enemies. Given the strong reliance of lacewings on pollen from nearby insect pollinated woody plants, the promotion of native shrubs and trees, such as Prunus, Salix and Castanea, should be prioritized for natural enemy enhancement in agricultural landscapes. Doing this in the form of hedgerows or agroforestry systems would lead to only minimal reduction in production areas and provide additional benefits such as biodiversity conservation.

Functional responses of a medium-ranging marine predator highlight the importance of frontal zones as foraging locations

The distribution of marine predators is linked to bio-physical processes that structure the spatio-temporal availability of prey species. Within shelf seas, tidal fronts are highly productive regions occurring at the interface between mixed and stratified waters. Fronts are predictable but dynamic features, with their timing and strength varying seasonally and annually. The availability of frontal habitats will also vary between animal populations depending on geographic location. Thus, understanding the associations between marine predators and frontal habitats across a range of environmental conditions will assist marine management and conservation. Here, we assessed functional responses of breeding black-legged kittiwakes Rissa tridactyla to environmental covariates related to tidal fronts (front strength, distance to fronts, sea surface temperature [SST] and surface chlorophyll concentration) from 10 UK colonies located throughout the North Sea. Kittiwakes showed a tendency to forage in areas of higher, but not maximal, front strength when such areas were available. Areas closer to fronts (<10 km) were selected when available, though we also observed increased usage of areas distant from fronts (30-50 km). Kittiwakes tended to forage in cooler, mixed waters, particularly as average SST rose. When average chlorophyll concentrations were low, habitat usage peaked in areas of higher chlorophyll. The results highlight the importance of frontal habitats and the dynamic, non-linear nature of seabird responses to habitat. Accounting for dynamic changes in habitat availability will play a key role in future conservation efforts, particularly as marine renewable installations and climate change may influence water stratification patterns.

Recovering predators link aquatic and terrestrial ecosystems: River otters subsidize coyotes with carrion.

Despite global declines in the abundance and distribution of predators, conservation and reintroduction efforts are increasingly leading to predator recoveries. Unexpected species interactions and ecological consequences often arise when these predator recoveries occur. Here, we describe a novel species interaction in which coyotes (Canis latrans) kleptoparasitize North American river otters (Lontra canadensis) in a region of river otter recovery along the north-central California coast, USA. We describe eight observations of coyotes scavenging otter-killed waterbird carrion, including one observation in which river otters aggressively defended their prey from a coyote kleptoparasite. These observations highlight the importance of carrion provisioning as an overlooked pathway through which river otters facilitate nutrient subsidies to terrestrial scavengers. This behavior may have ecological implications including effects on the abundance, behavior, and health of scavengers as well as their interspecific interactions. We propose hypotheses and questions regarding these ecological consequences to guide further investigations into the cross-ecosystem impacts of recovering river otter populations.

Multiple environmental stressors affect predation pressure in a tropical freshwater system

Environmental change can alter predator-prey dynamics. However, studying predators in the context of co-occurring environmental stressors remains rare, especially under field conditions. Using in situ filming, we examined how multiple stressors, including temperature and turbidity, impact the distribution and behaviour of wild fish predators of Trinidadian guppies (Poecilia reticulata). The measured environmental variables accounted for 17.6% of variance in predator species composition. While predator species differed in their associations with environmental variables, the overall prevalence of predators was greatest in slow flowing, deeper, warmer and less turbid habitats. Moreover, these warmer and less turbid habitats were associated with earlier visits to the prey stimulus by predators, and more frequent predator visits and attacks. Our findings highlight the need to consider ecological complexity, such as co-occurring stressors, to better understand how environmental change affects predator-prey interactions.

Intraguild processes drive space-use patterns in a large-bodied marine predator community.

Interspecific interactions, including predator-prey, intraguild predation (IGP) and competition, may drive distribution and habitat use of predator communities. However, elucidating the relative importance of these interactions in shaping predator distributions is challenging, especially in marine communities comprising highly mobile species. We used individual-based models (IBMs) to predict the habitat distributions of apex predators, intraguild (IG) prey and prey. We then used passive acoustic telemetry to test these predictions in a subtropical marine predator community consisting of eight elasmobranch (i.e. shark and ray) species in Bimini, The Bahamas. IBMs predicted that prey and IG prey will preferentially select habitats based on safety over resources (food), with stronger selection for safe habitat by smaller prey. Elasmobranch space-use patterns matched these predictions. Species with predator-prey and asymmetrical IGP (between apex and small mesopredators) interactions showed the clearest spatial separation, followed by asymmetrical IGP among apex and large mesopredators. Competitors showed greater spatial overlap although with finer-scale differences in microhabitat use. Our study suggests space-use patterns in elasmobranchs are at least partially driven by interspecific interactions, with stronger spatial separation occurring where interactions include predator-prey relationships or IGP.

At-sea distribution of marine predators around South Georgia during austral winter, with implications for fisheries management

The sub-Antarctic island of South Georgia is surrounded by highly productive waters, supporting dense aggregations of Antarctic krill (Euphausia superba), a vital food source for globally important seabird and marine mammal populations. These waters also support a commercial fishery for Antarctic krill. Regular monitoring of key krill predator species is undertaken at South Georgia to detect any changes in the ecosystem in response to harvesting activities. This monitoring provides essential data but is focused on land-breeding animals during the austral summer, whilst the krill fishery operates exclusively in winter. Here, we report the results of at-sea surveys to investigate abundance and distribution of krill-dependent predators from winter 2010 and 2011, which represented a “poor” krill year and “good” krill year, respectively. Correspondingly in 2011 higher numbers of krill predators were observed; notably Antarctic fur seals (Arctocephalus gazella) across the northern shelf. Spatial overlap between fur seals and the krill fishery occurred mainly within the krill fishery hotspot to the north-east, highlighting the potential for locally high levels of competition. Cetaceans were observed during both survey years, but in low numbers compared to recent studies. Gentoo penguins (Pygoscelis papua) were the most frequently observed penguin species, showing an inshore distribution and almost no overlap with the krill fishery. Diving-petrels (Pelecanoides spp.) were the most abundant flying seabirds, observed across all transects, with particularly high densities to the south in early winter 2010. In conclusion, this survey provides valuable baseline data on the distribution of South Georgia’s predators during the winter months.

Interactive effects of predation and climate on the distributions of marine shellfish in the Northwest Atlantic

As climate change transforms marine environments globally, species distributions correspondingly shift to locations where conditions have become or remain favourable. The ability to model these distributional shifts has been facilitated by species distribution models (SDMs). However, current SDM approaches have largely ignored climate‐driven changes in species interactions, which ultimately can have an important influence on species distributions. In this study, we utilize a long‐term, large‐scale dataset spanning 48 years and approximately 30 degrees latitude across the Canadian Atlantic shelf. We examine how climate influences the distribution and predation patterns of two invertebrates, northern shrimp Pandalus borealis and snow crab Chionoecetes opilio, aiming to evaluate the impacts of climate change on prey distributions. We found that both invertebrate species have a pronounced predicted response to climate change, with a northern shift in the distribution of northern shrimp and an overall reduction in abundance of both snow crab and shrimp associated with warming temperatures. Including predatory interactions as predictors in the SDMs (either directly via predator densities or via estimated predation rates) improved prediction accuracy for northern shrimp but not for snow crab. This is consistent with the ecology of these two species, as northern shrimp is more vulnerable to predation than snow crab. We found that the projections of future northern shrimp distributions are sensitive to the predicted spatial distribution and abundance of predators, highlighting the inherent complexity of predicting species response to climate change. Collectively, these results contribute to a broader literature that seeks to improve the capabilities of models to predict the effects of species interactions on species distributions under changing ecological conditions.

Integrated survey methodologies provide process-driven framework for marine renewable energy environmental impact assessment

Environmental interactions of marine renewable energy developments vary from fine-scale direct (e.g. potential collision) to indirect wide-scale hydrodynamic changes altering oceanographic features. Current UK Environmental Impact Assessment (EIA) and associated Habitats Regulations Appraisal (HRA) guidelines have limited focus on underlying processes affecting distribution and movements (hence vulnerability) of top predators. This study integrates multi-trophic ship survey (active acoustics and observer data) with an upward-facing seabed platform and 3-dimensional hydrodynamic model as a process-driven framework to investigate predator-prey linkages between seabirds and fish schools. Observer-only data highlighted the need to measure physical drivers of variance in species abundances and distributions. Active acoustics indicated that in situ (preferable to modelled) data were needed to identify temporal changes in hydrodynamics to predict prey and consequently top predator presence. Revising methods to identify key habitats and environmental covariates within current regulatory frameworks will enable more robust and transferable EIA and HRA processes and outputs, and at larger scales for cumulative and strategic-level assessments, enabling future modelling of ecosystem impacts from both climate change and renewable energy extraction.

Habitat associations of marine predators in the northern California Current during the low productivity downwelling season

IntroductionEastern Boundary Upwelling Systems are some of the most productive marine ecosystems in the world. Little is known about habitat associations and spatial distributions of marine predators during seasonal periods of low productivity because there are few at-sea surveys during this period. During low productivity or prey scarcity, predators consuming similar prey in the same time and space may compete for limited resources, or they may avoid competition by exploiting different habitats or occupying separate spaces (i.e. niche partitioning). In this study, we examined habitat associations and niche partitioning of marine predators during the low-productivity winter downwelling season of the northern California Current Ecosystem (CCE). MethodsSeabird and marine mammal counts were continuously collected during systematic at-sea surveys during February–March/April in the northern California Current across four years (2006, 2008, 2009, and 2012). We examined seabird and marine mammal distributions in relation to seven habitat characteristics [i.e., sea surface temperature (°C), salinity, depth (m), seafloor slope (%), distance from shore (km), and distance from the 100 m and 200 m isobaths (km)]. We used a non-parametric multivariate analysis [i.e. canonical correspondence analysis (CCA)] to quantify species’ habitat associations and directional distribution ellipses to explore overlap in species core winter habitat.ResultsResults show 49 seabird and ten marine mammal species inhabit the CCE during this low productivity period, including endangered southern resident killer whales (Orcinus orca). Seabirds and marine mammals exhibited significant but low overlap in habitat associations (i.e. weak niche partitioning) and similar habitat associations to summer studies. DiscussionWe also found that some species with similar foraging strategies showed asymmetrical spatial range overlap (i.e. common murre (Uria aalge) and parakeet auklet (Aethia psittacula)), which may mean that expected increased competition due to climate change can negatively affect some species more than others. Given that climate change is leading to increased frequencies, intensities, and durations of marine heat waves during winter months, addressing the winter ecology knowledge gap will be important to understanding how climate change is going to affect species that reside in or migrate through the northern California Current during the low productivity downwelling season.

Food web interactions of two breeding Arctic shorebird species, little stint Calidris minuta and red knot Calidris canutus, are shaped by their elevational distribution

Birds often have to choose their nest site location along a food safety axis, balancing nest predation danger with the food requirements of themselves and their offspring. This is probably most important for precocial species, such as most shorebirds, in which both chicks and parents need access to food resources in the surroundings of the nest, at least during the first days of life of the chicks. In many Arctic ecosystems, shorebird nests are typically prone to predation by both avian and terrestrial predators, especially in lemming-poor years. Among other factors, the strength of the trophic interactions between shorebirds, their prey, and their predators depend on how all of these are distributed across space. During two breeding seasons in northern Taimyr, North-Central Russia, we investigated how the spatial distribution of red knot Calidris canutus and little stint Calidris minuta nests and broods overlaps with the local food landscape and also with the distribution of avian predators and their main prey, lemmings. We found that the two shorebird species use different habitats that vary in arthropod community structure in accordance with the birds’ diet: while little stints selected lower elevations where chironomid midges Chironomidae are more abundant, red knots selected higher elevations where crane flies Tipulidae are more abundant. Furthermore, little stints share low-elevation habitats with lemmings and predators, while red knots inhabit higher elevations averted by both lemmings and avian predators. We found higher nest predation for little stint nests than for red knots nests, especially in a low-lemming year. Our results thus support the idea that food web interactions are driven by landscape and community aspects.

Cougars, wolves, and humans drive a dynamic landscape of fear for elk.

To manage predation risk, prey navigate a dynamic landscape of fear, or spatiotemporal variation in risk perception, reflecting predator distributions, traits, and activity cycles. Prey may seek to reduce risk across this landscape using habitat at times and in places when predators are less active. In multipredator landscapes, avoiding one predator could increase vulnerability to another, making the landscape of fear difficult to predict and navigate. Additionally, humans may shape interactions between predators and prey, and induce new sources of risk. Humans can function as a shield, providing a refuge for prey from human-averse carnivores, and as a predator, causing mortality through hunting and vehicle collisions and eliciting a fear response that can exceed that of carnivores. We used telemetry data collected between 2017 and 2021 from 63 Global Positioning System-collared elk (Cervus canadensis), 42 cougars (Puma concolor), and 16 wolves (Canis lupus) to examine how elk habitat selection changed in relation to carnivores and humans in northeastern Washington, USA. Using step selection functions, we evaluated elk habitat use in relation to cougars, wolves, and humans, diel period (daytime vs. nighttime), season (summer calving season vs. fall hunting season), and habitat structure (open vs. closed habitat). The diel cycle was critical to understanding elk movement, allowing elk to reduce encounters with predators where and when they would be the largest threat. Elk strongly avoided cougars at night but had a near-neutral response to cougars during the day, whereas elk avoided wolves at all times of day. Elk generally used more open habitats where cougars and wolves were most active, rather than altering the use of habitat structure depending on the predator species. Elk avoided humans during the day and ~80% of adult female mortality was human caused, suggesting that humans functioned as a "super predator" in this system. Simultaneously, elk leveraged the human shield against wolves but not cougars at night, and no elk were confirmed to have been killed by wolves. Our results add to the mounting evidence that humans profoundly affect predator-prey interactions, highlighting the importance of studying these dynamics in anthropogenic areas.

Conspecific density drives sex-specific spatial wintertime distribution and hoarding behaviour of an avian predator

Most studies on intraspecific competition, i.e., competition among individuals of the same species, have been conducted during the breeding season. Yet, at northern latitudes, intraspecific competition is expected to be particularly strong under the harsh weather conditions of the non-breeding season with limited number of resources available per individual. We studied the food-hoarding behaviour of wintering Eurasian Pygmy Owls (Glaucidium passerinum) along with sex- and age-specific spatial distribution in relation to fluctuating main prey abundance (voles) and conspecific density using a 15-year dataset. In low vole abundance years, increasing conspecific density reduced the total prey number stored by an owl, suggesting high costs of exploitative competition. The distance between the stores of nearest neighbours was greater when both were females, suggesting that the spatial avoidance is driven by sex-specific competition. However, food stores of females had a larger amount of prey items, especially when the nearest neighbour was of the same sex. The number of stores hoarded by an owl increased with increasing conspecific densities. Distributing the prey items to multiple store-sites instead of one (shifting from larder-hoarding towards scatter-hoarding) can help to reduce the overall loss to potential pilfering when conspecific density is high. These results combined suggest that high conspecific density inflames sex-specific interference competition, rather than solely exploitative competition, and in turn drives the observed sex-specific spatial distribution. Adopting a sex-specific spatial distribution according to hoarding and aggressive behaviour can be a way to reduce the severity of intraspecific competition locally and could have cascading effects on the prey community.

Predator–Prey Dynamics and Ideal Free Distribution in a Heterogeneous Environment

The concept of an ideal free distribution (IFD) is extended to a predator–prey system in a heterogeneous environment. We consider reaction–diffusion–advection equations which describe the evolution of spatial distributions of predators and prey under directed migration. Modification of local interaction terms is introduced, if some coefficients depend on resource. Depending on coefficients of local interaction, the different scenarios of predator distribution are possible. We pick out three cases: proportionality to prey (and respectively to resource), indifferent distribution and inversely proportional to the prey. These scenarios apply in the case of nonzero diffusion and taxis under additional conditions on diffusion and migration rates. We examine migration functions for which there are explicit stationary solutions with nonzero densities of both species. To analyze solutions with violation of the IFD conditions, we apply asymptotic expansions and a numerical approach with staggered grids. The results for a two-dimensional domain with no-flux boundary conditions are presented.

Nest defence of urban and rural Common Kestrels Falco tinnunculus against different predators

ABSTRACT Common Kestrels Falco tinnunculus breeding in a rural environment reacted more aggressively to dummies of potential predators than did those breeding in an urban environment. During the nestling phase, the Kestrels reacted more frequently than during the incubation phase and males reacted more often than females. The reactions to dummies partially reflected the distribution of predators in the urban and rural areas.

A paradigm for understanding whole ecosystem effects of offshore wind farms in shelf seas

Abstract With the rapid expansion of offshore windfarms (OWFs) globally, there is an urgent need to assess and predict effects on marine species, habitats, and ecosystem functioning. Doing so at shelf-wide scale while simultaneously accounting for the concurrent influence of climate change will require dynamic, multitrophic, multiscalar, ecosystem-centric approaches. However, as such studies and the study system itself (shelf seas) are complex, we propose to structure future environmental research according to the investigative cycle framework. This will allow the formulation and testing of specific hypotheses built on ecological theory, thereby streamlining the process, and allowing adaptability in the face of technological advancements (e.g. floating offshore wind) and shifting socio-economic and political climates. We outline a strategy by which to accelerate our understanding of environmental effects of OWF development on shelf seas, which is illustrated throughout by a North Sea case study. Priorities for future studies include ascertaining the extent to which OWFs may change levels of primary production; whether wind energy extraction will have knock-on effects on biophysical ecosystem drivers; whether pelagic fishes mediate changes in top predator distributions over space and time; and how any effects observed at localized levels will scale and interact with climate change and fisheries displacement effects.