Population effects of shrimp trawl bycatch on Atlantic croaker

2000 ◽  
Vol 57 (10) ◽  
pp. 2010-2021 ◽  
Author(s):  
Sandra L Diamond ◽  
Lindsay G Cowell ◽  
Larry B Crowder
Keyword(s):  
Negative Impact ◽  
Population Level ◽  
Adult Mortality ◽  
Atlantic Croaker ◽  
First Year ◽  
Population Declines ◽  
Micropogonias Undulatus ◽  
Population Growth Rates ◽  
Juvenile Mortality ◽  
Shrimp Trawl

We used stage-within-age based matrix models of Atlantic croaker (Micropogonias undulatus) in the Gulf of Mexico and the South and Mid-Atlantic bights to explore the population-level impacts of shrimp trawl bycatch on estuarine-dependent fishes and to investigate tradeoffs between directed adult fisheries and bycatch mortality. The Gulf model reflected a rapidly declining population, while the Atlantic population showed a modest decline. Elasticity analyses indicated that both populations were more sensitive to the summed survival of adults than first-year survival, particularly in the Gulf. Contrary to our expectations, bycatch mortality on late juveniles was not the most important factor affecting either population of Atlantic croaker, and this result was robust to uncertainty in both adult and late juvenile mortality estimates. Both populations were most sensitive to ocean larva mortality, followed by mortality of estuary larvae and adults in the Gulf and of early juveniles and adults in the Atlantic. Nonetheless, bycatch mortality did have a large negative impact on population growth rates, and reducing late juvenile or adult mortality by about 35% in the Gulf or 5% in the Atlantic should reverse population declines. Bycatch reduction devices currently in use can achieve these desired reductions.

Demography of Xenosaurus platyceps (Squamata: Xenosauridae): a comparison between tropical and temperate populations

2008 ◽  
Vol 29 (2) ◽  
pp. 245-256 ◽  
Author(s):  
Carissa Jones ◽  
Isaac Rojas-González ◽  
Julio Lemos-Espinal ◽  
Jaime Zúñiga-Vega
Keyword(s):  
Life History ◽  
Population Growth ◽  
Adult Mortality ◽  
Life History Strategies ◽  
Relative Importance ◽  
Theoretical Frameworks ◽  
Population Growth Rates ◽  
Relative Contribution ◽  
Two Populations ◽  
Average Fitness

Abstract There appears to be variation in life-history strategies even between populations of the same species. For ectothermic organisms such as lizards, it has been predicted that demographic and life-history traits should differ consistently between temperate and tropical populations. This study compares the demographic strategies of a temperate and a tropical population of the lizard Xenosaurus platyceps. Population growth rates in both types of environments indicated populations in numerical equilibrium. Of the two populations, we found that the temperate population experiences lower adult mortality. The relative importance (estimated as the relative contribution to population growth rate) of permanence and of the adult/reproductive size classes is higher in the temperate population. In contrast, the relative importance for average fitness of fecundity and growth is higher in the tropical population. These results are consistent with the theoretical frameworks about life-historical differences among tropical and temperate lizard populations.

Breeding ecology of the fairy martin

1999 ◽  
Vol 47 (5) ◽  
pp. 463 ◽  
Author(s):  
Michael J. L. Magrath
Keyword(s):  
Breeding Season ◽  
Weather Conditions ◽  
Adult Mortality ◽  
First Year ◽  
Breeding Ecology ◽  
Adult Males ◽  
Annual Productivity ◽  
Adverse Weather ◽  
Colony Site ◽  
The One

The breeding biology of the fairy martin, Hirundo ariel, was studied over three years (1992–95) in the Yarra Valley, Victoria. Adult males and females in this population were morphologically similar, though only females acquired a brood patch during the breeding season. Colonies ranged in size from 8 to 29 nests. Birds arrived in the study area in September and usually commenced laying in October, though nesting activities were generally asynchronous both between and within colonies. Most colonies contained active nests until February. At least 16% of adults and 5% of fledglings, on average, returned to the study area in the following year. Returning adults generally nested at the same colony site as the previous year, while most first-year birds nested at sites other than their natal colony. Adult males were more likely to return than adult females. Clutch size ranged from 2 to 5, with a mean of 3.5, and declined over the season. The incubation period varied from 12 to 18 days with a mean of 13.7. A mean of 1.8 chicks fledged per completed clutch, while 60% of clutches produced at least one chick. The period from hatching to fledging varied from 17 to 32 days, with a mean of 22.1, and increased with brood size. Fledging success was highest during the middle of the breeding season. Adverse weather conditions, resulting in the abandonment of clutch and brood, were the most common cause of nest failure, and on several occasions also resulted in adult mortality. Almost half the breeding females produced at least two clutches in the one season. Pairs produced from 0 to 8 fledglings per season, with those that commenced nesting earlier in the season having higher annual productivity. These results are discussed in relation to the breeding ecology of other members of the Hirundinidae.

Assessment of invasive rodent impacts on island avifauna: methods, limitations and the way forward

2015 ◽  
Vol 42 (2) ◽  
pp. 185 ◽  
Author(s):  
Lise Ruffino ◽  
Diane Zarzoso-Lacoste ◽  
Eric Vidal
Keyword(s):  
Population Growth ◽  
Population Level ◽  
Bird Conservation ◽  
Bird Population ◽  
Breeding Parameters ◽  
Population Growth Rates ◽  
Bird Populations ◽  
Field Evidence ◽  
Bird Breeding

Bird conservation is nowadays a strong driving force for prioritising rodent eradications, but robust quantitative estimates of impacts are needed to ensure cost-effectiveness of management operations. Here, we review the published literature to investigate on what methodological basis rodent effects on island bird communities have been evaluated for the past six decades. We then discuss the advantages and limitations of each category of methods for the detection and quantification of impacts, and end with some recommendations on how to strengthen current approaches and extend our knowledge on the mechanisms of impacts. Impact studies (152 studies considered) emphasised seabirds (67%), black rats (63%) and the Pacific Ocean (57%). Among the most commonly used methods to study rodent impacts on birds were the observation of dead eggs or empty nests while monitoring bird breeding success, and the analyses of rodent diets, which can both lead to misleading conclusions if the data are not supported by direct field evidence of rodent predation. Direct observations of rodent–bird interactions (19% of studies) are still poorly considered despite their potential to reveal cryptic behaviours and shed light on the mechanisms of impacts. Rodent effects on birds were most often measured as a change or difference in bird breeding parameters (74% of studies), while estimates of bird population growth rates (4%) are lacking. Based on the outcomes of this literature review, we highlight the need for collecting unbiased population-level estimates of rodent impacts, which are essential prerequisites for predicting bird population growth scenarios and prioritising their conservation needs. This could be achieved by a more systematic integration of long-term monitoring of bird populations into rodent management operations and modelling bird population dynamics. We also strongly recommend including various complementary methods in impact assessment strategies to unravel complex interactions between rodents and birds and avoid faulty evidence. Finally, more research should be devoted to a better understanding of the cases of non-impacts (i.e. long-term coexistence) and those impacts mediated by mechanisms other than predation and ecosystem-level processes.

scholarly journals Value-Based HIV Care: A Method to Improve Quality of HIV Care.

2020 ◽  
Author(s):  
Guido van den berk ◽  
Daoud Ait Moha ◽  
Janneke Stalenhoef ◽  
Marie-Jose Kleene ◽  
Narda van der Meche ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Care Delivery ◽  
Population Level ◽  
Care Quality ◽  
Hiv Care ◽  
First Year ◽  
Outcome Indicators ◽  
Number Of Patients ◽  
Care Path

Abstract Background : To support our goal of providing optimal HIV care to our patients, we started applying the value-based health care principle to the HIV care that we offer in our HIV center, measuring relevant health outcomes and costs to allow continuous implementation of improvements (Value-Based HIV Care; VBHiC). Methods : In line with the principles of Michael Porter, our approach consisted of the following steps: 1) Organizing into integrated practice units / describing the HIV care path; 2) Defining an HIV outcome indicator set; 3) Building an enabling information technology platform; 4) Integrating care delivery across separate facilities; 5) Moving to bundled payments for care cycles and 6) Expanding excellent services and interventions for improvement across geographic boundaries. Results : The following set of 9 outcome indicators was developed: undetectable HIV load within the first year of care; quality of life within the first year of care; mortality within the first year of care; retention in care; therapy effectiveness; therapy tolerance; cardiovascular risk; quality of life for every subsequent year and overall annual mortality. These indicators, which were evaluated retrospectively, are shown in figures 1-5. Collection of the underlying data started in January 2016. The HIV care path was also integrated into the electronic file system. Creation of the ability to monitor outcome indicators at patient level, population level and process level allowed us to implement a quality cycle (plan-do-study-act). Conclusion : Our Value-Based HIV Care approach facilitated structured evaluation of parameters that are of value to the patient. It also boosted the quality of the HIV care that we provide and allowed us to increase the number of patients to whom we can offer high quality HIV care.

scholarly journals Opposite outcomes of coinfection at individual and population scales

2018 ◽  
Vol 115 (29) ◽  
pp. 7545-7550 ◽  
Author(s):  
Erin E. Gorsich ◽  
Rampal S. Etienne ◽  
Jan Medlock ◽  
Brianna R. Beechler ◽  
Johannie M. Spaan ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Negative Impact ◽  
Scale Up ◽  
Population Level ◽  
Clear Understanding ◽  
African Buffalo ◽  
Global Public Health ◽  
Individual Level ◽  
Secondary Infections ◽  
The Individual

Coinfecting parasites and pathogens remain a leading challenge for global public health due to their consequences for individual-level infection risk and disease progression. However, a clear understanding of the population-level consequences of coinfection is lacking. Here, we constructed a model that includes three individual-level effects of coinfection: mortality, fecundity, and transmission. We used the model to investigate how these individual-level consequences of coinfection scale up to produce population-level infection patterns. To parameterize this model, we conducted a 4-y cohort study in African buffalo to estimate the individual-level effects of coinfection with two bacterial pathogens, bovine tuberculosis (bTB) and brucellosis, across a range of demographic and environmental contexts. At the individual level, our empirical results identified bTB as a risk factor for acquiring brucellosis, but we found no association between brucellosis and the risk of acquiring bTB. Both infections were associated with reductions in survival and neither infection was associated with reductions in fecundity. The model reproduced coinfection patterns in the data and predicted opposite impacts of coinfection at individual and population scales: Whereas bTB facilitated brucellosis infection at the individual level, our model predicted the presence of brucellosis to have a strong negative impact on bTB at the population level. In modeled populations where brucellosis was present, the endemic prevalence and basic reproduction number (R0) of bTB were lower than in populations without brucellosis. Therefore, these results provide a data-driven example of competition between coinfecting pathogens that occurs when one pathogen facilitates secondary infections at the individual level.

scholarly journals Risk of depression in family caregivers: unintended consequence of COVID-19

BJPsych Open ◽  
2020 ◽  
Vol 6 (6) ◽  
Author(s):  
Stephen Gallagher ◽  
Mark A. Wetherell
Keyword(s):  
Mental Health ◽  
Family Caregivers ◽  
Depressive Symptomatology ◽  
Negative Impact ◽  
General Health Questionnaire ◽  
Population Level ◽  
Poor Mental Health ◽  
Unintended Consequences ◽  
Depression Symptoms ◽  
Data Set

Background Coronavirus disease 2019 (COVID-19) is likely to exacerbate the symptoms of poor mental health in family caregivers. Aims To investigate whether rates of depressive symptomatology increased in caregivers during COVID-19 and whether the unintended consequences of health protective measures, i.e., social isolation, exacerbated this risk. Another aim was to see if caregivers accessed any online/phone psychological support during COVID. Method Data (1349 caregivers; 6178 non-caregivers) was extracted from Understanding Society, a UK population-level data-set. The General Health Questionnaire cut-off scores identified those who are likely to have depression. Results After adjustment for confounding caregivers had a higher risk of having depressive symptoms compared with non-caregivers, odds ratio (OR) = 1.22 (95% CI 1.05–1.40, P = 0.008) evidenced by higher levels of depression pre-COVID-19 (16.7% caregivers v. 12.1% non-caregivers) and during the COVID-19 pandemic (21.6% caregivers v. 17.9% non-caregivers), respectively. Further, higher levels of loneliness increased the risk of depression symptoms almost four-fold in caregivers, OR = 3.85 (95% 95% CI 3.08–4.85, P < 0.001), whereas accessing therapy attenuated the risk of depression (43%). A total of 60% of caregivers with depression symptoms reported not accessing any therapeutic support (for example online or face to face) during the COVID-19 pandemic. Conclusions COVID-19 has had a negative impact on family caregivers’ mental health with loneliness a significant contributor to depressive symptomatology. However, despite these detriments in mental health, the majority of caregivers do not access any online or phone psychiatric support. Finally, psychiatric services and healthcare professionals should aim to focus on reducing feelings of loneliness to support at-risk caregivers.

Does working to pay for higher education really harm French academic results?

2019 ◽  
Vol 40 (4) ◽  
pp. 591-615 ◽  
Author(s):  
Liliane Bonnal ◽  
Pascal Favard ◽  
Kady Marie-Danielle Sorho-Body
Keyword(s):  
Higher Education ◽  
Negative Impact ◽  
Working Hours ◽  
Drop Out ◽  
First Year ◽  
Content Type ◽  
Explanatory Variables ◽  
Student Profiles ◽  
The Impact ◽  
Academic Results

Purpose This paper is the first of its kind to look at first-year undergraduates in France. The purpose of this paper is to measure the impact of holding down a job on the probability of students dropping out of higher education or passing their first year. Design/methodology/approach Given the existence of relevant unobserved explanatory variables, probit models with two simultaneous equations have been estimated. The first equation will enable us to explain paid employment or working hours, and the second academic outcomes that allow for dropout. Findings The results show that being employed means students are more likely to drop out during their first year and less likely to pass. The latter finding is comparable with results for subsequent academic years although the impact is greater for first-year undergraduates. The more intensive the work, the greater the adverse effects of employment. Originality/value By refining the research, this negative impact of employment is not verified for all the student profiles. For some of them, e.g., those with honours at the secondary bachelor, employment does not harm their academic results.

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