Derelict and active fishing gear poses a threat to marine wildlife. This study details Indo-Pacific bottlenose dolphin entanglements in recreational fishing gear in the Peel-Harvey Estuary, Western ...Australia between 2016 and 2022. Eight entanglements were recorded, three resulted in death. While concerning from an animal welfare perspective, the impact of entanglements on the viability of the local dolphin population was low. This is as majority of affected individuals were juvenile males. Should entanglements result in the loss of reproductive females, or impact their reproductive success, the population trajectory could quickly change. As such, management decision making should consider population level impacts as well as the welfare of entangled individuals. Government agencies, together with relevant stakeholders, should work together to maintain preparedness to respond to entanglements and take preventative action that lowers the risk of interactions with recreational fishing gear.
•Interactions with recreational fishing gear pose a threat to coastal dolphins.•Population viability may be threatened if adult females are lost due to entanglements.•Poor welfare of entangled individuals should trigger management action.•Preparedness to respond to incidents should be maintained.•Preventative action should be taken to lower the risk of dolphin entanglements.
Obtaining morphometric data on free-ranging marine megafauna is difficult, as traditional methods rely on post-mortem or live-capture techniques. We linked stereo-laser photogrammetry with long-term ...demographic data to compare length-at-age (LaA) growth curves of two well-studied populations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western (SW) and Shark Bay (SB), mid-western Australia. First, we determined the relationship between total length (TL) and blowhole-to-dorsal fin (BH-DF) length from post-mortem subjects (R
= 0.99, n = 12). We then predicted TL from laser-derived BH-DF measurements of 129 and 74 known-age individuals in SW and SB, respectively. Richards growth models best described our LaA data. While birth length (103-110 cm) was similar between study regions, TL estimates at 1, 3, 12, and 25 years differed significantly (p < 0.001). Asymptotic length of adult males (SW = 246 cm, SB = 201 cm) and females (SW = 244 cm, SB = 200 cm) also differed significantly. Morphotypic variations likely reflect regional adaptations to local water temperatures, with the temperate SW having cooler waters than sub-tropical SB. We demonstrate the effectiveness of a non-invasive technique to understand ecological, demographic and life-history characteristics of long-lived marine megafauna, which are critical parameters for informing conservation and management actions.
The incidental capture of wildlife in fishing gear presents a global conservation challenge. As a baseline to inform assessments of the impact of bycatch on bottlenose dolphins (Tursiops truncatus) ...interacting with an Australian trawl fishery, we conducted an aerial survey to estimate dolphin abundance across the fishery. Concurrently, we carried out boat-based dolphin photo-identification to assess short-term fidelity to foraging around trawlers, and used photographic and genetic data to infer longer-term fidelity to the fishery. We estimated abundance at ≈ 2,300 dolphins (95% CI = 1,247-4,214) over the ≈ 25,880-km
fishery. Mark-recapture estimates yielded 226 (SE = 38.5) dolphins associating with one trawler and some individuals photographed up to seven times over 12 capture periods. Moreover, photographic and genetic re-sampling over three years confirmed that some individuals show long-term fidelity to trawler-associated foraging. Our study presents the first abundance estimate for any Australian pelagic dolphin community and documents individuals associating with trawlers over days, months and years. Without trend data or correction factors for dolphin availability, the impact of bycatch on this dolphin population's conservation status remains unknown. These results should be taken into account by management agencies assessing the impact of fisheries-related mortality on this protected species.
We present a Hierarchical Bayesian version of Pollock's Closed Robust Design for studying the survival, temporary-migration, and abundance of marked animals. Through simulations and analyses of a ...bottlenose dolphin photo-identification dataset, we compare several estimation frameworks, including Maximum Likelihood estimation (ML), model-averaging by AICc, as well as Bayesian and Hierarchical Bayesian (HB) procedures. Our results demonstrate a number of advantages of the Bayesian framework over other popular methods. First, for simple fixed-effect models, we show the near-equivalence of Bayesian and ML point-estimates and confidence/credibility intervals. Second, we demonstrate how there is an inherent correlation among temporary-migration and survival parameter estimates in the PCRD, and while this can lead to serious convergence issues and singularities among MLEs, we show that the Bayesian estimates were more reliable. Third, we demonstrate that a Hierarchical Bayesian model with carefully thought-out hyperpriors, can lead to similar parameter estimates and conclusions as multi-model inference by AICc model-averaging. This latter point is especially interesting for mark-recapture practitioners, for whom model-uncertainty and multi-model inference have become a major preoccupation. Lastly, we extend the Hierarchical Bayesian PCRD to include full-capture histories (i.e., by modelling a recruitment process) and individual-level heterogeneity in detection probabilities, which can have important consequences for the range of phenomena studied by the PCRD, as well as lead to large differences in abundance estimates. For example, we estimate 8%-24% more bottlenose dolphins in the western gulf of Shark Bay than previously estimated by ML and AICc-based model-averaging. Other important extensions are discussed. Our Bayesian PCRD models are written in the BUGS-like JAGS language for easy dissemination and customization by the community of capture-mark-recapture practitioners.
The UK scientific community is rightly concerned about the impact of leaving the EU on UK science. These concerns are particularly pertinent for mental health research, which is chronically ...underfunded in comparison to research on physical health conditions. The EU is one of the largest funders of mental health research in the world, with the UK clearly benefitting from this because of its strong track record. Any loss of funding, leadership or influence would weaken this. Likewise if we are unable to attract the best or most promising researchers from the rest of Europe, the loser will not just be research into mental health across Europe, but patients themselves. Those working on the Brexit negotiations must develop clear and coherent plans to safeguard scientific research in UK and ensure that the momentum gained in mental health policy in recent years is not lost.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Conspecifics may vary in their space use and diet leading to niche partitioning within populations. In social species, such partitioning may correspond to social structure as closely associated ...individuals likely encounter the same resources. This study investigated whether space use and diet varied among social clusters of a resident estuarine population of Indo-Pacific bottlenose dolphins. Dolphin photo-identification and behavioral data, as well as tissue samples for stable isotope analysis, were collected during boat-based surveys in the Peel-Harvey Estuary, Western Australia. Potential dolphin prey species were also collected for stable isotope analyses. Six mixing models, one assuming an invariant diet and others allowing for variation in diet according to sex, age class, and/or social cluster, were fitted to the data. The model with social cluster was the best fit and estimated detritivorous fish as the main dietary source for social clusters whose core activity space covered the eastern shores of the estuary and the rivers. These clusters occupied the lowest trophic position in the dolphin population. Benthic omnivores and carnivores contributed most to the diet of clusters whose core activity space included the two estuary entrances. These clusters occupied the highest trophic position. Clusters with core activity space located in the estuary basins reflected the overall mean contributions of fish feeding guilds to dolphin diet in this population. Detritivores, omnivores and herbivores, and benthic omnivores and carnivores each contributed approximately a third and water column species the remainder to the annual fish biomass removed from the estuary by the dolphin population. We conclude that dolphins share resources with fishers and piscivorous birds within the estuary.
Significance statement
This study identified intra-population resource partitioning according to social structure in a resident estuarine dolphin population. The heterogeneity in space use and diet among social clusters may result in individuals being susceptible to different pressures and threats. The dolphins’ foraging behavior and trophic interactions identified them as an apex predator in the Peel-Harvey Estuary, with their collective minimum annual food intake (~ 200,000 kg) exceeding the annual fish biomass removed by commercial fishers. As top predators in the system, dolphins may suppress prey populations through consumption and as agents of intimidation by changing prey distribution and behavior. This study provides scientific basis for recognizing dolphins as an important component of the Peel-Harvey Estuary ecosystem.
Investigations of population structure across multiple niche dimensions can identify discrete management units within populations. This study examined social, spatial and isotopic niche partitioning ...in Indo‐Pacific bottlenose dolphins (Tursiops aduncus) across ca. 600 km2 of coastal and estuarine waters in south‐western Australia, to evaluate whether estuarine dolphins should be treated as a discrete management unit.
Photo‐identification data and tissue samples were collected in 2016 and 2017 in a study area covering the Peel‐Harvey Estuary (PHE) and adjacent coastal waters. A total of 1,038 dolphin groups were encountered, and 481 individuals were identified. Tissue samples for stable isotope (δ13C and δ15N) analyses were collected from 96 individuals. Social structure and complexity analyses were conducted, full and core activity spaces were identified, and their size estimated for identified social communities. Differences in stable isotope composition among individuals and communities were examined.
A socially, spatially and isotopically distinct dolphin community occurred in the PHE. The coastal waters contained four socially and spatially, but not isotopically, distinct communities as well as a substantial number of dolphins (n = 185) that were sighted infrequently and therefore were not assigned to any community. Individuals formed three levels of relationships; the majority (78%) were weak association relationships (mean half‐weight index 0.006). The estuarine community had significantly higher mean δ13C and significantly lower mean δ15N values than any of the coastal communities.
There is a strong scientific basis for treating the PHE dolphin community as a discrete management unit. The estuarine and coastal communities occupied different social environments, with coastal individuals sharing space with more transient individuals. This study shows the value of integrating information from multiple niche dimensions when identifying management units, and the need to consider all encountered individuals in management planning.
Wildlife management requires reliable demographic information to assess the status of a population and its vulnerability to threats. This study calculated age class‐ and sex‐specific demographic ...parameters and assessed the viability of a community of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) resident to the Peel‐Harvey Estuary in Western Australia. Boat‐based photo‐identification surveys (n = 483) were conducted between 2016 and 2019. A population viability analysis (PVA) was used to assess the community status and evaluate the effects of adult female and calf mortality, and reproduction on population growth rate. The community comprised 88 (SD = 4.43) individuals with a sex ratio close to parity in all but the adult age class where it was skewed towards females. Demographic changes in this community are driven by births, deaths, and the likely permanent emigration of juvenile males. No immigration was observed. The population is stable (r = −0.004, SD = 0.062) given the current demographic rates. To maintain a community of ~90 individuals, management should consider action to lower adult female and calf mortality. This should involve aiming for zero human caused mortality and ensuring adverse impacts to the population are considered in future development planning.
The Women, ART and the Criminalization of HIV Study is a qualitative, arts-based research study focusing on the impact of the HIV non-disclosure law on women living with HIV in Canada. The federal ...law requires people living with HIV to disclose their HIV-positive status to sexual partners before engaging in sexual activities that pose what the Supreme Court of Canada called a 'realistic possibility of transmission'. Drawing on findings from seven education and discussion sessions with 48 women living with HIV regarding HIV non-disclosure laws in Canada, this paper highlights the ways in which women living with HIV respond to learning about the criminalisation of HIV non-disclosure. The most common emergent themes included: the way the law reproduces social and legal injustices; gendered experiences of intimate injustice; and the relationship between disclosure and violence against women living with HIV. These discussions illuminate the troubling consequences inherent in a law that is antithetical to the science of HIV transmission risk, and that fails to acknowledge the multiple barriers to HIV disclosure that women living with HIV experience. Women's experiences also highlight the various ways the law contributes to their experiences of sexism, racism and other forms of marginalisation in society.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Thiazolidinediones, commonly used antidiabetic medications, have been associated with an increased risk of development of diabetic macular oedema and increased vascular endothelial cell permeability. ...Macular neovascularisation in age-related macular degeneration (AMD) and associated fluid leakage may be influenced by thiazolidinediones. This study aims to determine the association between thiazolidinedione usage and retinal morphological outcomes or visual acuity (VA) in patients treated with bevacizumab or ranibizumab for neovascular AMD (nAMD).
Secondary analysis of data from the Comparison of Age-related Macular Degeneration Treatments Trials. Participant self-reported diabetes status and thiazolidinedione usage at baseline. VA, intraretinal, subretinal and subretinal pigment epithelium fluid, and foveal thickness of retinal layers were evaluated at baseline and during 2-year follow-up. Comparisons of outcomes between thiazolidinedione usage groups were adjusted by macular neovascularisation lesion type in multivariable regression models.
Patients taking thiazolidinedione (n=30) had lower adjusted mean VA score at baseline (difference -6.2 letters; p=0.02), greater proportion with intraretinal fluid (IRF) at year 2 (75% vs 50%, adjusted OR 2.8; p=0.04), greater mean decrease in subretinal tissue complex thickness from baseline at year 1 (difference -75.1 um; p=0.02) and greater mean decrease in subretinal thickness at year 1 (difference -41.9 um; p=0.001) and year 2 (difference -43.3 um; p=0.001).
In this exploratory analysis, patients with diabetes taking thiazolidinediones and treated with bevacizumab or ranibizumab for nAMD had worse baseline mean VA, greater reductions in subretinal and subretinal tissue complex thickness from baseline, and greater proportions with IRF comparing to patients not taking thiazolidinediones.
ClinicalTrials.gov NCT00593450.
PDF
