Search

Animals living near urban habitats face many pressures linked with human disturbance. While individuals vary in their ability to cope with disturbance, it is predicted that individuals in highly disturbed environments will be bolder and more aggressive than those in less disturbed environments. Using little penguins, Eudyptula minor, we investigated whether individual aggressiveness was consistent across trials and whether aggressiveness was greater in colonies that experience higher levels of unregulated human disturbance. We scored aggressiveness at the nest, based on the penguins’ response to a standardized nest intrusion experiment, across four penguin colonies in South Australia. Nest defence scores were significantly repeatable over two trials, suggesting that it was a good indicator of personality in little penguins. Island was a significant predictor of nest defence score, with little penguins on Granite Island (the island with the greatest amount of unregulated human disturbance) being more aggressive than those on Troubridge Island (the island with the lowest amount of human disturbance). Considering that humans increasingly interact with animals, whether directly or indirectly, understanding the mechanisms behind nonrandom distribution of behaviours may have important implications for population management and conservation.

In many locations, the highest proportion of roaming dogs and cats, might have owners. The prevention of roaming in owned dogs and cats is a key intervention to reduce the number of unsupervised animals in public spaces. Sterilization is an important population management intervention but it is unclear if, apart from its effects on birth rates and animal behavior, it also affects the roaming status of owned dogs and cats. We formulated a directed acyclic graph to represent a causal hypothesis regarding the effect of sex, age and sterilization on roaming behavior in owned dogs and cats. The causal hypothesis was tested using survey data and Bayesian multilevel logistic regressions. The odds of roaming were lower in sterilized dogs and cats but the credible interval (CI) supported the effect of sterilization only for dogs. The odds of roaming were higher in both male dogs and cats and the CI supported the effect of sex. The CI did not support the effect of age on roaming, irrespective of species. If the observed association between sterilization and roaming was causal, then sterilization may contribute to a reduction in roaming. Studies on other populations and the exploration of other potential determinants of roaming are required to better understand the causal relationship between sterilization and roaming.

Humans and their associated anthropogenic factors may strongly affect the demographics, activity and fragmentation of wild animal populations. Yet, the degree and nature of such impact on indicators of animals' social relationships remain largely under-investigated, despite the well-documented importance of strong social ties for an individual's health and fitness. Here, we examined whether interactions with humans may affect core aspects of social life in a primate species, by constraining the time available for individuals to engage in social interactions. Specifically, we predicted that individuals who spend more time monitoring or interacting with humans would reduce their time socializing with conspecifics (i.e. the time constraints hypothesis). Alternatively, human presence may result in increased levels of stress, leading to an increase in social behaviours that serve as a coping mechanism (i.e. the social stress hypothesis). We collected data between September 2016 and September 2017 on four groups of longtailed macaques, Macaca fascicularis, in Malaysia at two sites with differing levels of human impact. In support of the time constraints hypothesis, we found that at the site with moderate human impact, monkeys who monitored human activity more frequently engaged less often in grooming. In contrast, at the site with high human impact, we found evidence supporting the social stress hypothesis, as indicators of stress were positively associated with social interactions, although we could not link them to the presence of humans. Our results suggest that the nature of human impact on macaques' social behaviour is dependent upon the intensity of human activity and interaction with the macaques. These findings therefore provide insights into how humans may influence individual fitness and group social structure in animals living in an anthropogenic environment. More broadly, our results may lead to a better understanding of animal behaviour in anthropogenic environments, implementing conservation and population management strategies and mitigating human–wildlife conflict.

The coronavirus disease 2019 (COVID-19) pandemic has shattered the meticulously developed processes by which we delivered quality care for patients with cirrhosis. Care has been transformed by the crisis, but enduring lessons have been learned. In this article, we review how COVID-19 will impact cirrhosis care. We describe how this impact unfolds over 3 waves; i) an intense period with prioritized high-acuity care with delayed elective procedures and routine care during physical distancing, ii) a challenging 'return to normal' following the end of physical distancing, with increased emergent decompensations, morbidity, and systems of care overwhelmed by the backlog of deferred care, and iii) a protracted period of suboptimal outcomes characterized by missed diagnoses, progressive disease and loss to follow-up. We outline the concrete steps required to preserve the quality of care provided to patients with cirrhosis. This includes an intensification of the preventative care provided to patients with compensated cirrhosis, proactive chronic disease management, robust telehealth programs, and a reorganization of care delivery to provide a full service of care with flexible clinical staffing. Managing the pandemic of a serious chronic disease in the midst of a global infectious pandemic is challenging. It is incumbent upon the entire healthcare establishment to be strong enough to weather the storm. Change is needed.

We present and mathematically analyze a singular stochastic control model for cost-effective and ecologically-sound indirect population control strategy for fish-eating birds. Finding the optimal strategy of a threshold type reduces to solving a variational inequality. We prove the unique existence of its viscosity solution that is neither convex nor concave, which turns out to be a classical solution. Comparative statics on the optimal threshold is performed as well to demonstrate practical implications of the model.

As an introduction to the Special Issue on the restoration of threatened plant species and their habitats, this editorial shows how the various papers in the issue address the range of in situ interventions involved in species population management and restoration of their habitat, together with examples of case studies implementing these actions. It stresses the need for integrating these various interventions. It highlights the importance of protected areas in providing a degree of protection for threatened species but also the need to complement this with actions at the species level to ensure the effective conservation and long term persistence of these species. It emphasizes that ecological restoration is a complement to, not a substitute for conservation, and that the balance of effort and allocation of resources between them is a key issue. Keywords: Threatened species management, Habitat restoration, In situ conservation, Protected areas

Although pet population management programs have been established worldwide, few reports on program evaluation have been carried out to date. Accordingly, a 3-year longitudinal study has been carried out in a 4000 household neighborhood located within the metropolitan area of Curitiba, the eighth most populated city of Brazil. Visits were conducted and questionnaires completed to estimate and characterize the local pet population (animal sex, reproductive and vaccination status, street access). Care provided by owners, community perception on stray dog management and the possible changes were compared in these variables over time (2010 and 2013) were evaluated, after the establishment of a city pet population management program. In addition, associations between having children, owning dogs and cats, responsible pet ownership education and owner's perception on stray dogs were statistically tested. A total of 354/4000 (8.9%) household families were interviewed in 2010 and 70/354 (19.8%) of the same families again in 2013. No significant changes were found in overall number of dogs and cats and average pet age, animal care and owner's perception on stray dogs following the 3-year population management program. In 2010, an average of 1.6 dogs and 0.3 cats were found per family, with slightly more females (51.3% dogs and 51.1% cats), adults (4.0±3.5years for dogs and 2.1±2.4 for cats), intact (not neutered; 94.2% dogs and 84.0% cats) and lacking regular visit to veterinarian (71.6%). Although more families (53.1%) had children under 12 years old, no association was found between having children and having dogs and cats. Questionnaires revealed that owners perceived neutering/spaying to be the best pet population control method (42.4%), with "society" (50%) and "government" (49.4%) as responsible for pet population management. A significant positive association has been found between education level and the best way to control stray dogs (p=0.03), between having dogs and in favor of neutering/spaying (p=0.04) and considering neutering/spaying as the best control method (p=0.02). The chances of thinking the best way to control stray dogs by neutering/spaying and adoption were almost 2.0 fold higher than other methods. In conclusion, the present study has provided indicators (education level, having dogs) for pet population control program assessment and effectiveness evaluation. Moreover, this study may serve as a warning on the real long-term effect of such programs, which should be periodically evaluated to identify necessary adjustments and/or improvements.

In this paper, a new parameter for population management is implemented in the Differential Evolution algorithm. The new scheme integrates a set of operators that analyze the exploration and exploitation effects during its operation. With these operators, the new method obtains important knowledge about its population diversity during its evolution. Under such conditions, the proposed method can reduce its population when the diversity is too low in order to reduce its computational cost and improve its search capacities simultaneously. To test the new additions, the proposed algorithm has been tested in a set of 29 complex functions and two interplanetary trajectory design problems. The outcome of the tests demonstrates a greatly improved performance when compared to the original Differential Evolution algorithm, a few of its most successful variants, and other algorithms.

Long-term, multi-institutional assessments have become a reliable tool for evaluating patterns of wounding in zoo-living primates, with results informing on best practices for species-specific care protocols and population management strategies. For western lowland gorillas (Gorilla gorilla gorilla) there has been no detailed reports focused on mixed-sex groups, the most common social group type for this species in zoos. In this study, wounding data were collected over 26 months for 131 gorillas living in 26 social groups at 18 zoos and analyzed in relation to age, sex, and group demographic variables. Adult females received wounds at significantly higher rates than adult males suggesting sexual dimorphism and the disparate social roles of male and female gorillas may differentially affect wounding rates. Group size was associated with increased wounding in adult gorillas, however, wounding rates overall were low in frequency and severity. Wound locations were not randomly located, with wounds to the trunk accounting for 24 % of all wounds. These data provide useful insights that may help inform and improve management of gorillas in mixed-sex groups. Specifically, understanding that vulnerability to wounding may be more prevalent in females compared to males can inform strategies aimed at improving husbandry, health, and welfare and have a positive impact on population management practices for the species.

To gain an overview of crocodile species held in zoos, the number of individuals kept, and the number of keeping institutions, we analyzed collection information from the Zoological Information Management System (ZIMS) database. Our analysis performed from June to July 2016 revealed that there were 24 species of crocodiles kept globally in 451 zoos, with 22 species kept in 185 European zoos. Two globally-kept species were lacking in European zoo holdings according to ZIMS. Of the 27 currently recognized species of crocodiles, one (Mecistops sp.) is not held in zoos at present. In addition we have opposed ZIMS data with information available from European studbooks and, based on literature evaluation, analyzed the development of crocodile collections in Europe during the last 40 years. Although ZIMS data is not complete, there is a trend discernible that only a few species are widely kept by the zoo community, whereas most species are represented in smaller numbers. We further discuss the importance of “Regional Collection Plans”, viz. long-term crocodile collection planning, and provide recommendations for population management such as considering a shift from very commonly kept species towards species that are in greater need of conservation support through zoo husbandry efforts.

A chronic and progressive illness, diabetes requires early diagnosis, effective coordination of care, and self-management to stem its progression. Population health management strategies hold promise to improve outcomes by focusing on reducing the frequency of acute and chronic complications of chronic disease, lowering the cost per service through an integrated care delivery team approach, and promoting patient engagement. This will ultimately result in a better patient experience. The chronic care model targets fragmentation of our health care delivery system and provides a framework for effective care of diabetes and other chronic diseases.

Management strategies for dog populations and their diseases include reproductive control, euthanasia and vaccination, among others. However, the effectiveness of these strategies can be severely affected by human-mediated dog movement. If immigration is important, then the location of origin of dogs imported by humans will be fundamental to define the spatial scales over which population management and research should apply. In this context, the main objective of our study was to determine the spatial extent of dog demographic processes in rural areas and the proportion of dogs that could be labeled as immigrants at multiple spatial scales. To address our objective we conducted surveys in households located in a rural landscape in southern Chile. Interviews allowed us to obtain information on the demographic characteristics of dogs in these rural settings, human influence on dog mortality and births, the localities of origin of dogs living in rural areas, and the spatial extent of human-mediated dog movement. We found that most rural dogs (64.1%) were either urban dogs that had been brought to rural areas (40.0%), or adopted dogs that had been previously abandoned in rural roads (24.1%). Some dogs were brought from areas located as far as ∼700km away from the study area. Human-mediated movement of dogs, especially from urban areas, seems to play a fundamental role in the population dynamics of dogs in rural areas. Consequently, local scale efforts to manage dog populations or their diseases are unlikely to succeed if implemented in isolation, simply because dogs can be brought from surrounding urban areas or even distant locations. We suggest that efforts to manage or study dog populations and related diseases should be implemented using a multi-scale approach.

Patient and family navigation is an emerging strategy to address the complexity of care experienced during prolonged hospitalizations and extended follow-up care. An innovative navigator program for extremely premature infants was developed and implemented in an 85 bed level IV neonatal unit. The family navigator model addresses the psychological needs of the neonatal families by providing individualized anticipatory guidance and support as the family moves through their child's hospital experience. Program experts titled Neonatal Family Navigators serve as a consistent liaison to facilitate information sharing, offer education and promote a multidisciplinary team approach with the neonatal patient and family at the center of the team. This program demonstrated positive outcomes including improved family satisfaction metrics, decreased length of stay, and enhanced the overall coping mechanisms of families who experience an extended neonatal hospital stay.

Recreational hunters have largely replaced natural predators of white-tailed deer ( Odocoileus virginianus ) across much of North America; thereby, providing the greatest form of risk (both direct and indirect) to survival. On a 1861-ha property in Oklahoma, USA, we evaluated how controlled hunting influenced movement behaviour (using movement rate [m/h] and relative displacement index [%]) of 37 adult (≥2.5 years) male deer at three risk treatment levels (i.e., control = no risk; low-risk = 1 hunter/101 ha; and high-risk = 1 hunter/30 ha), two temporal periods of risk (i.e., diurnal [06:00–18:00] and nocturnal [18:00–06:00]), and across time (36 days); time was modelled as a continuous variable that covered five risk exposure periods (risk present or absent in brackets; i.e., pre-season [absent], scout [present], pre-hunt [absent], hunt [present], and post-hunt [absent]). Movement rate (m/h) decreased over time for all risk treatment levels and temporal period of risks; however, the magnitude (i.e., slope) of decrease varied across treatments. The magnitude of decrease in movement rate was similar for control and low risk treatments during diurnal and nocturnal periods, but was different between low and high risk, and high risk and control treatments. Relative displacement (%) of deer was greatest at the start of the study, decreasing during the study finally resulting in displacement values being three times less after hunting season. Deer responded to the presence of hunters on the landscape by adapting movement strategies both spatially and temporally to avoid potential contact with hunters. During the study, deer reduced movements and used smaller areas more intensively, as indicated by the relative displacement index. Reducing movement or space use may lead to lower detection of deer by hunters, thus increasing the probability of survival through reduced harvest. Understanding deer behavioural responses to hunters (and at different levels of risk) could be used to facilitate or reduce harvest based on population management objectives.

The family Rhinocerotidae with many species spread around the world was a distinct feature of the global Pleistocene fauna, but most of these species are now extinct. Three of the five surviving species are critically endangered, due to habitat loss and a surge in criminal hunting for horns. To save these iconic species, conservation science will have to apply all methods at its disposal, from population management through to advanced genomics and forensics. Michael Gross reports.

Infectious diseases are a major threat to both managed and wild pollinators. One key question is how the movement or transplantation of honeybee colonies under different management regimes affects honeybee disease epidemiology. We opportunistically examined any persistent effect of colony management history following relocation by characterising the virus abundances of honeybee colonies from three management histories, representing different management histories: feral, low-intensity management, and high-intensity "industrial" management. The colonies had been maintained for one year under the same approximate 'common garden' condition. Colonies in this observational study differed in their virus abundances according to management history, with the feral population history showing qualitatively different viral abundance patterns compared to colonies from the two managed population management histories; for example, higher abundance of sacbrood virus but lower abundances of various paralysis viruses. Colonies from the high-intensity management history exhibited higher viral abundances for all viruses than colonies from the low-intensity management history. Our results provide evidence that management history has persistent impacts on honeybee disease epidemiology, suggesting that apicultural intensification could be majorly impacting on pollinator health, justifying much more substantial investigation.

Population management of free-roaming domestic dogs (Canis lupus familiaris) is of interest due to the threat these animals pose to people, other animals and the environment. Current sterilization procedures for male dogs include surgical and chemical methods. However, little is known about how these procedures affect their behavior. The primary objective of this study was to investigate changes in selected behaviors following chemical and surgical sterilization in a male free-roaming dog (FRD) population in southern Chile. We also examined the association between serum testosterone levels and behaviors thought to be influenced by circulating androgens. A total of 174 dogs were randomly assigned to either a surgical or chemical sterilization group, or a control group. At the onset of the intervention period, 119 dogs remained and 102 dogs successfully completed the study. Each dog was monitored pre- and post-intervention using video recordings, GPS collars, and blood samples for the measurement of testosterone. Analysis of behavior revealed that surgically castrated dogs showed no reduction of sexual activity or aggression when compared to their pre-intervention behavior. Chemically sterilized dogs showed a statistically significant increase in dog-directed aggression, but no change in sexual activity. There was no change in home range size in any groups between the pre- and post-intervention measurement. We found no consistent association between levels of serum testosterone concentration and behavioral changes in any of the groups. This study presents the first detailed behavioral observations following surgical and chemical sterilization in male FRDs. The information generated is highly relevant to communities struggling with the control of FRDs. Complementary studies to further our understanding of the effects of male sterilization on the behavioral and reproductive dynamics of FRD populations are needed.

For many years critical issues of zoo biology and breeding management were not fully communicated by zoos, nor were they realized or questioned by the general public. This has changed within the last few decades, leading to an increase in the transparency and credibility of zoos. I conducted qualitative research on how zoos communicate critical issues to the public by using semi-structured expert interviews, focusing on the issues of euthanasia, contraception and ’carcass-feeding’. The results draw a preliminary picture of how critical issues are currently communicated in European zoos, with a focus on Germany. Zoos can be divided into three groups: (1) those who communicate critical issues directly by displaying them to the public, (2) those who prefer a more indirect way of explaining these issues, and (3) those who neglect to communicate any critical issues. A list of methods used, as well as arguments for and against communication, was extracted out of the responses of the survey group. Furthermore, a first draft for Critical Issue Management (CIM) for zoos was developed and described, using the study results as well as recommendations for crisis communication. There is a great need to conduct further research about how communication from zoos is received by visitors and the general public. Nevertheless, the results suggest that zoos need to find a basic international agreement on how to communicate critical issues as part of a multi-institutional CIM, and to establish regional communication guidelines for critical issues.

Experimental and theoretical studies show that mortality imposed on a population can counter-intuitively increase the density of a specific life-history stage or total population density. Understanding positive population-level effects of mortality is advancing, illuminating implications for population, community, and applied ecology. Reconciling theory and data, we found that the mathematical models used to study mortality effects vary in the effects predicted and mechanisms proposed. Experiments predominantly demonstrate stage-specific density increases in response to mortality. We argue that the empirical evidence supports theory based on stage-structured population models but not on unstructured models. We conclude that stage-specific positive mortality effects are likely to be common in nature and that accounting for within-population individual variation is essential for developing ecological theory.

This paper presents two algorithms combining GRASP and Tabu Search for solving the Unconstrained Binary Quadratic Programming (UBQP) problem. We first propose a simple GRASP-Tabu Search algorithm working with a single solution and then reinforce it by introducing a population management strategy. Both algorithms are based on a dedicated randomized greedy construction heuristic and a tabu search procedure. We show extensive computational results on two sets of 31 large random UBQP instances and one set of 54 structured instances derived from the MaxCut problem. Comparisons with state-of-the-art algorithms demonstrate the efficacy of our proposed algorithms in terms of both solution quality and computational efficiency. It is noteworthy that the reinforced GRASP-Tabu Search algorithm is able to improve the previous best known results for 19 MaxCut instances.

A B S T R A C T Population control in some form of harvesting might be expected to reduce population size, but quite the opposite can happen due to the hydra effect. This phenomenon describes an increase in population size with increased mortality. One mechanism causing hydra effects is the temporal separation of (i) harvesting and (ii) density-dependent reproduction. Here we consider discrete-time models of these two processes. It is commonly believed that harvesting needs to precede reproduction for a hydra effect to occur. We show that, by contrast, hydra effects also take place for harvest after reproduction. Due to the timing of population census, however, the hydra effect will not be measured and thus remains ‘hidden’. As a consequence, managers may miss out on the opportunity to increase both the yield and the remaining stock of renewable resources. If harvesting aims at controlling pest species, management interventions may backfire in the sense that the pest increases rather than decreases—and, to make things even worse, this may actually go unnoticed. To remedy these undesirable consequences, we propose a modelling framework that can reveal hidden hydra effects. Our results are based on rigorous mathematical proofs that the order of two events does not matter for standard harvesting/hunting strategies.

Sunflower ( Helianthus annuus L.) became an economically important crop in North Dakota in the 1970s, providing a major source of food for post-breeding blackbirds (Icteridae). Reducing local blackbird populations with rice grains treated with an avicide is one proposed alternative for reducing sunflower damage. In fall 2007 and 2008, we evaluated the idea of attracting blackbirds to rice-baited trays attached to wire cages supplied with live blackbirds. During our observations (1011 h), we saw 3888 birds, consisting of 25 species and 12 families, on the bait trays. Blackbirds made up 90.4% of the bird observations, whereas sparrows (Emberizidae) made up 1.6% of the birds observed. Overall risk to non-target species appeared minimal. The bait trays, however, attracted a small number of blackbirds compared to the source population feeding in nearby crop fields. Our results strongly suggest DRC-1339-treated rice used on bait trays is unlikely to be a cost-effective method of reducing blackbird damage to ripening sunflower.

Sea lamprey invaded the Great Lakes in the early 20th century and caused an abrupt decline in the population densities of several native fish species. The integrated management of this invasive species is composed of chemical (lampricide) applications, low-head barrier dams, adult trapping and sterile male release. Recently, there has been an increased emphasis on the development of control methods alternative to lampricide applications. We propose as an alternative-control method the use of chemosensory cues as repellents for sea lamprey population management. Based on the available evidence at this time, we suggest that injury-released chemical alarm cues show promise as repellents for sea lamprey and further research should be directed at determining whether sea lamprey show an avoidance response to these types of chemosensory cues. From a management perspective, these chemosensory cues could be used to restrict sea lamprey access to spawning grounds. Repellents could also be used together wit...

9 páginas,3 tablas, 4 figuras., Ecosystem modifiers have the ability to significantly alter the ecosystem they inhabit sometimes with serious consequences for their own populations. We evaluated the ability of greenturtles (Cheloniamydas) to modify seagrassecosystems by their foraging activity. This study was conducted in a seagrass-dominated lagoon in the Lakshadweep Islands, Indian Ocean, where a stable high-density congregation of greenturtles is present. We determined a gradient of turtledensity in the lagoon and measured the intensity of turtle herbivory across the gradient. We then measured the impact of increasing grazing on seagrass structural parameters, growth and flowering along this gradient. Our results indicate that turtlessubstantially change seagrassmeadow structure (canopy height, shoot length, width and density), reduce flowering and can potentially even cause changes in the species composition of the meadow. We discuss the implications of these results for seagrassecosystem function, greenturtle movement and human attitudes. When conservingecosystem modifiers like the greenturtle, any management strategy needs to include a detailed knowledge of the roles these species play in the ecosystems they inhabit., This work was supported by the Wildlife Institute of India, Norwegian Institute for Nature Research (NINA) and The Ford Foundation.

International audience; We present a diversity-oriented hybrid evolutionary approach for the graph coloring problem. This approach is based on both generally applicable strategies and specifically tailored techniques. Particular attention is paid to ensuring population diversity by carefully controlling spacing among individuals. Using a distance measure between potential solutions, the general population management strategy decides whether an offspring should be accepted in the population, which individual needs to be replaced and when mutation is applied. Furthermore, we introduce a special grouping-based multi-parent crossover operator which relies on several relevant features to identify meaningful building blocks for offspring construction. The proposed approach can be generally characterized as “well-informed”, in the sense that the design of each component is based on the most pertinent information which is identified by both experimental observation and careful analysis of the given problem. The resulting algorithm proves to be highly competitive when it is applied on the whole set of the DIMACS benchmark graphs.

This paper proposes a modified version of real immune algorithm (RIA) using population management, namely, RIAPM, to simultaneous coordinated tuning of power system stabilizers (PSSs) in a power system. A conventional lead-lag structure is considered for the controllers. Since, the parameters of lead-lag controllers are continuous variables to be found and an infinite number of candidate solutions will exist, therefore a modification will be considered to RIA to reduce the search space gradually, in order to get a more detailed investigation in a smaller region. Using the RIAPM, the parameters of the damping controllers are optimized simultaneously and the interactions among the controllers are considered. The numerical results are presented on a 2-area 4-machine system to illustrate the feasibility of the proposed method. To show the effectiveness of the designed controllers, a three-phase fault is applied at a bus. The simulation study shows that the RIAPM performs better than RIA.

Allee effects, strongly related to the extinction vulnerability of populations and gradually becoming acknowledged by both theoretically oriented and applied ecologists, have already been shown to have important roles in the dynamics of many populations. Although not yet widely recognized, two or more Allee effects can occur simultaneously in the same population. Here, we review the evidence for multiple Allee effects and show that their interactions can take several forms, many of which are far from inconsequential. We suggest that more research is needed to assess the prevalence and interactions of multiple Allee effects, as failing to take them into account could have adverse conse- quences for the management of threatened or exploited populations.

Many populations have a negative impact on their habitat, or upon other species in the environment, if their numbers become too large. For this reason they are often managed using some form of control. The objective is to keep numbers at a sustainable level, while ensuring survival of the population. Here we present models that allow population management programs to be assessed. Two common control regimes will be considered: reduction and suppression. Under the suppression regime the population is maintained close to a particular threshold through near continuous control, while under the reduction regime, control begins once the population reaches a certain threshold and continues until it falls below a lower pre-defined level. We discuss how to best choose the control parameters, and we provide tools that allow population managers to select reduction levels and control rates. Additional tools will be provided to assess the effect of different control regimes, in terms of population persistence and cost. In particular we consider the effects of each regime on the probability of extinction and the expected time to extinction, and compare the control methods in terms of the expected total cost of each regime over the life of the population. The usefulness of our results will be illustrated with reference to the control of a koala population inhabiting Kangaroo Island, Australia.

Population management, the optimisation of release and harvesting regimes, is a key element of effective fisheries stock enhancement. Population dynamics theory and assessment methods are becoming available to support management decision-making in enhanced fisheries. To apply such approaches in practice, it is necessary to estimate growth and mortality parameters for the target fishery. Here I show how this information can be extracted from release experiments through use of a size-dependent mortality model. The model, which describes natural mortality as an inverse function of fish length, has been derived in an earlier study and enjoys strong empirical support. Analysis of release experiments using this model provides direct estimates of size-dependent natural and fishing mortality patterns, which can be used to predict recapture and yield under alternative release and harvesting regimes. Furthermore, by expressing size-dependent mortality in terms of a single parameter, the mortality rate Mr at reference length Lr, the model facilitates comparative analyses of data from experiments in which mortality rates have been measured for different fish sizes. A preliminary comparative analysis shows that natural mortality is more variable, and substantially higher on average, in released hatchery-reared fish (median Mr = 13.3 year −1 ) than in wild fish (median Mr = 3.3 year −1 ) for the same reference length (Lr = 5 cm). Such comparative information provides a benchmark against which the effectiveness of releases may be evaluated. Application of the approach is illustrated through the analysis of published data from a cod (Gadus morhua) release experiment in Norway. © 2006 Elsevier B.V. All rights reserved.

We compared two assessments of the status of gopher tortoise populations at 10 protected sites in Florida, taken about a decade apart. We assessed status indirectly, using surveys of burrows along belt transects. Transect placement and timing were identical between surveys. We compared numbers of burrows, relative numbers of burrows of different activity conditions, and size distributions of burrows between surveys. The comparisons indicated that populations had declined at as many as eight of the sites. We found no strong connection between population decline and decline in habitat quality, as reflected in decreased ground cover and/or increased canopy cover between surveys. The response of a population to decline in habitat quality may depend on initial habitat structure, the degree of change in habitat structure, the period of time over which change is measured, the amount of habitat involved, and the level of habitat management.

Three typical African partial harvesting systems and an unfished control were compared for gross yield. Fish grew undisturbed on an input regime based on that used by Malawian smallholding farmers for 122 days. Then, for an additional 143 days, ponds were partially harvested once per week by hook and line, seining with a reed fence or basket trapping. Hook and line fishing and seining with a reed fence partially harvested a significantly (P

A study was undertaken, modeling Black rhino, Diceros bicornis, populations from Hluhluwe-Umfolozi Game Reserve and Mkuzi Game Reserve, Republic of South Africa. This study had two specific goals. Firstly, we tried to find a simple model to predict the population number in the following year and give insight in the number of animals that can be removed from the population. Secondly, the use of different models gave us the opportunity to evaluate the effect of small differences in model structure on the outcome of the models. Five different models were tested, mainly focusing on the structure of density dependence. The density dependent model, that incorporated stronger density dependence at high densities, fitted best to the observed census values. The study, furthermore, indicated that the population in Hluhluwe-Umfolozi is stabilizing. The situation in Mkuzi was not that clear. Based on these results, managers should therefore be more careful with removing animals from this population. Finally the results clearly showed that different model structures can result in very different model outcomes. Besides in the values of the model parameters, this was also shown by different values for the population number where the yearly increase is maximal. Based on these results it does not seem wise to base management decisions solely on the outcome of one model. Therefore, we strongly encourage managers to compare the outcome from different model structures, based on different biological assumptions.

In central Europe, rodent damage in cereal crops is usually attributed to the common vole but these are caused by other rodents such as Apodemus mice as well. This raises a practical problem of identifying the rodent pests causing the damage to cereals at the time of harvest. To facilitate field differentiation between the damage caused by voles or mice, we conducted laboratory experiments in which the common vole, wood mouse and pygmy field mouse were presented with standing culms of wheat. Harvesting behaviour in these rodents differed strikingly. Wood mice first climbed and then cut down the culm at a height of about 20 cm. Pygmy field mice climbed to the top of the culm, harvesting only the ear. Voles cut the culm close to the ground leaving the stubble of about 8 cm in height. Our observations provide a quick and simple clue for identifying a causal rodent species in cereals and help in adopting a proper strategy for population management of a pest rodent.

Previous research has demonstrated the cost-effectiveness of pVAD hemodynamic support for emergent and elective high-risk heart failure patients. In addition, our published budget impact models show a minimal per-member-per-month impact for payers. Consistent with health reform trends, this study's

The selective removal of carnivores from local areas is sometimes proposed to reduce the number of attacks on livestock. For the lynx, neither the existence of problem individuals nor the efficacy of their selective removal has been demonstrated. In France, from 1989 to 1999, eight lynx and two large carnivores thought to be lynx were legally removed from high conflict areas by trapping ( n =7), shooting ( n =1) or poisoning with toxic collars on sheep ( n =2). The efficacy of the 10 removals was assessed on the farms where a lynx was caught and in the 5-km-radius areas encompassing both these farms and nearby sheep farms. The sex-ratio of captured lynx was seven males:one female. On four farms and in six 5-km-radius areas lynx attacks on sheep reappeared within 40 days after lynx removal, but we observed a significant decrease in the overall number of attacks. In the medium-term (48–365 days), the number of attacks decreased on two farms and in four 5-km radius areas when compared with the number observed in control plots >10 km away from the removal sites. In the long-term, attacks reappeared on the same sites, indicating a “site” effect. In such situations, selective removals may only temporarly reduce the problem of concentrated lynx damage. The only way to obtain a durable effect is to improve shepherding techniques.

The most important linefish species, silver kob Argyrosomus inodorus was assessed using two yield-per-recruit approaches, Beverton and Holt and Thompson and Bell. For the Beverton and Holt model, the analysis was run using three different values of natural mortality and depletion of the stock was estimated to be between 14 and 35%. Using the Thompson and Bell method, uncertain values of parameters such as catches, natural mortality and terminal fishing mortality were modelled using Monte Carlo simulations with a pseudo-cohort analysis. For this analysis, it was estimated that the stock was depleted below F SB(40%) . In addition, natural mortality versus fishing mortality per age class was investigated and it was found that natural mortality was higher for the first three age classes. Based on the analysis it was recommended that the commercial fishery should be subjected to a total allowable catch, a license system should be introduced, bag limits should be lowered and a maximum size limit be implemented.

Many studies have been conducted to estimate the parameters of Indian Ocean albacore ( Thunnus alalunga ) fishery. Various estimates on the same parameter from these studies have resulted in uncertainty and confusion when management strategies are made. This study incorporates these estimates in the simple yield-per-recruit model through Monte Carlo simulations to derive management implication under parameter uncertainty. The results provided an optimal management suggestion under the following conditions. First, the probability of obtaining feasible simulation results was greater than 95%; second, the probability of increase to yield-per-recruit after regulatory change was also greater than 95%. Under these conditions, the results suggested if the goal of management was to increase the relative yield-per-recruit of the Indian Ocean albacore stock by 30% and more, the relative selection size should be changed by +0.15 to +0.25 and the exploitation rate by −0.5 to +0.15.

The concept of the ‘stock’ is fundamental for both fisheries and endangered species management. We review different approaches used in identifying and classifying stocks and advocate that an holistic approach (e.g., involving a broad spectrum of complementary techniques) be used in future stock identification studies. Stock definitions should evolve as management requirements do and be re-evaluated when the need arises or when break-through technologies become available.

The identification and discrimination of stocks of fishes lies at the interesting juncture of fishery biology and fish microevolution. Fish have been “taken apart” in the search for features that discriminate between stocks. Early stock studies focused on morphological characters (meristic counts and morphometric measurements) that are expressed phenotypically, and hence, benefit from incorporation of both genetic and environmental information, but suffer from the absence of information on their respective contributions. However, the ability to discriminate stocks has risen with the emergence of more sophisticated laboratory and statistical tools. Some of these techniques are mostly sensitive to environmental information, i.e., microchemical analysis of otoliths. Others are purely genetic (i.e., various forms of DNA sequence analysis), and reflect time, selection pressure, and the degree of isolation among populations. But despite this diversity of approaches, all are based on a common principle: the signal from the among-stock variation must exceed the noise of within-stock variation. Much of the uncertainty concerning the application of stock concept approaches stems from the lack of synchronicity in the development of the many potentially differentiating features between fish stocks. If so, then this field would benefit from a greater understanding of the trajectories of differentiation of analyzable features-gained from comparison between approaches from a microevolutionary point of view. Because only heterogeneity, and not homogeneity of fish stocks can be demonstrated, and because sophisticated stock identification is costly, it is imperative to select an appropriate approach from the outset. Unfortunately, comparative studies among stock identification approaches have only rarely been conducted. Although this “black art” could continue to muddle along, there is no doubt that useful information on the relative sensitivities of stock analysis techniques would be gained via well-planned intercalibration studies.

In a fish stock delineation study based on MANOVA/MANCOVA of a morphometric data set, use of measurements on many characters will result in a statistical artifact generating spurious significant differences between populations. A preliminary method is demonstrated for testing the presence of this artifact. Data analyzed for stock identification purposes should employ only a small number of morphometric characters, perhaps three or four.

The possibility of teaching naive animals about predators is often considered, but rarely implemented. By presenting model predators to free-living families of New Zealand robins Petroica australis, we showed that young robins learned to respond fearfully towards the predator. Robins held in captivity also learned to fear the predator when conditioning techniques were used. We argue that training about predators is an important and achievable component of any management programme designed to prepare endangered species for release into the wild. The techniques used here were simple, cheap, quick to apply, and resulted in significant adjustments in the response of young birds to a predator.

An echosounder with a tape recorder in a propeller-driven waterproof box (an echosounder shuttle) was used under the ice to monitor the vertical distribution and density of fish in a winter seining area of a Finnish lake in April 1997. The surveyed fish were at 3.5–8 m depth, and fish density was significantly lower after seining than before. The seine catch was about 10 kg ha−1, and the echosounding results showed a decrease of 7 kg ha−1 in the hauling area. There were some difficulties due to the low temperature, and minor problems with steering and leakage of the shuttle. We conclude that it is possible to make mobile echosurveys under the ice and estimate densities of wintering fish.

Conservation, harvesting and pest control are three aspects of the same general problem: population management. All three involve intervention with the aim of regulating population size and growth in some way, yet the dissociation of these disciplines is pervasive. Recent developments and a comparison of approaches show the potential of a synthetic paradigm.

Management of the Falkland Islands Loligo gahi fishery is by a combination of effort control and in-season assessment of the state of the stock in relation to biological reference points. There are two fishing seasons, from February to May and from August to October inclusive. There appear to be at least two, and sometimes three cohorts that recruit to the fishery over a year, in January, April/May and October. The fishing seasons therefore do not directly coincide with the separate cohorts; the second cohort is caught in both the first and second seasons. Assessments of the cohorts were made using a Delury depletion model. In situations when a Delury could not be fitted satisfactorily, an extension was developed in which annual trends in catchability coefficients were used together with individual vessel CPUE data to estimate stock size. The Delury and its extension enabled both first and second cohorts to be assessed for all years from 1987 to 1996. Results indicated that the cohorts have different dynamics and should be considered as separate stocks. Both cohorts have been declining in size over the last several years. The significance of a transition between two distinct stocks in a single fishing season is discussed in the context of real-time management of this fishery.

Translocations of rare and endangered species face significant valuational and organizational challenges; however, these dimensions are rarely discussed in the translocation literature. We employed a 98 question sample mail survey to assess these variables and received 131 responses from 110 individuals in 10 nations. In contrast to the literature which suggests that most translocations fail, a large proportion of the programs surveyed were perceived as being successful and most respondents identified relatively few valuational or organizational problems or difficulties in their translocation programs. While perceived local support was correlated with perceived translocation success, the presence of public relations/education programs was not. Therefore, simply having a public relations/education program is no guarantee that public support will increase or that a translocation will be more successful. Organizationally, translocations which established special groups or teams were perceived as increasing innovation, but not in improving program organization, nor decreasing conflict. Further, the presence of special groups or teams was not correlated with translocation success. Finally, translocations with the objective of augmenting populations were perceived to suffer from more problems, including greater local opposition, poorer public understanding, less money, and poorer leadership, than were translocations aimed at establishing or re-establishing populations. The results illustrated the difficulty of analyzing valuational and organizational aspects of conservation programs using questionnaires.

The rhesus monkey Macaca mulatta and Hanuman langur Presbytis entellus are distributed all over the State of Himachal Pradesh, India. Although both species inhabit forested areas, only rhesus monkeys seem also to have become urbanized. There are about 200,000 rhesus monkeys and 120,000 Hanuman langurs. A three-year survey at Shimla showed an increasing trend in their populations. Potential threats to survival of these primates differ in the 12 districts. The two species differ in feeding and habitat preferences. People's feelings, perceptions and attitudes toward them point to an incipient man-monkey conflict and erosion of conservation ethics. A comprehensive management plan for these primates should be formulated, and involve local people.

Fisheries science was the precursor of population ecology and continues to contribute important theoretical advances. Despite this, fishery scientists have a poor record for applying their insights to real-world fisheries management. Is there a gulf between theory and application or does the high variability inherent in fish populations and complexity of multispecies fisheries demand a different approach to management? Perhaps the solution to the world fisheries crisis is obvious after all?