Live-trapping of the northern hairy-nosed wombat (Lasiorhinus krefftii): population-size estimates and effects on individuals

1995 ◽  
Vol 22 (6) ◽  
pp. 741 ◽  
Author(s):  
SD Hoyle ◽  
AB Horsup ◽  
CN Johnson ◽  
DG Crossman ◽  
H McCallum
Keyword(s):  
Population Size ◽  
Confidence Limit ◽  
Mark Recapture ◽  
Population Size Estimate ◽  
Live Trapping ◽  
Population Size Estimates ◽  
Minimum Number ◽  
Estimate Population Size ◽  
Second Period ◽  
Size Estimates

The northern hairy-nosed wombat, one of the most endangered large mammals known, occurs only in Epping Forest National Park, central Queensland. The results of a 3-stage trapping programme, carried out between 1985 and 1993, were used to estimate population size by means of three separate modelling approaches: minimum number alive (MNA), mark-recapture, and trapping effort. Trapping procedure varied among sessions, and each estimator was applied to sessions only where its use was appropriate. The population-size estimate for 1985-86 was 67 (trap effort) with MNA of 58; for 1988-89 it was 62 (Jolly-Seber mark-recapture estimate), with MNA of 48 and upper 95% confidence limit of 77; and for 1993 it was 65 (Chao mark-recapture and trap effort), with MNA of 43 and upper 95% confidence limit of 186 (Chao mark-recapture). No population trends were observed, although variability in estimates and wide confidence intervals meant that power to do so was limited. Trapping affected the health and behaviour of wombats. Animals that were trapped twice within 10 nights lost an average of 0.62 kg (P = 0.006) between captures. Wombats that were trapped twice within the first four nights of traps being set on a burrow showed less weight loss than those trapped for the second time after 5-7 nights (0.23 kg v. 1.54 kg). The effects of trapping appeared to remain with animals for some time, since animals trapped twice more than 30 nights apart and within six months weighed an average of 0.5 kg less (P = 0.013) on second capture. When areas were trapped twice in succession with a 3-week gap, population-size estimates were lower for the second period of trapping. Thus, some wombats may have temporarily left areas disturbed by trapping. The deleterious impact of trapping may be reduced by restricting trapping to periods of four nights. Trapping effectiveness may be increased by minimising disturbance immediately before trapping and by moving traps between periods of trapping.

scholarly journals Population size estimates of pink river dolphins (Inia geoffrensis) using mark-recapture methods on photo-identification

2014 ◽  
Vol 9 (2) ◽  
pp. 132-139 ◽  
Author(s):  
Catalina Gómez-Salazar ◽  
Hal Whitehead ◽  
Fernando Trujillo
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Freshwater Ecosystems ◽  
Mark Recapture ◽  
Photo Identification ◽  
Population Size Estimate ◽  
Population Size Estimates ◽  
Inia Geoffrensis ◽  
Colombian Amazon ◽  
Size Estimates

Population size estimates of pink river dolphins (Inia geoffrensis) are critical to assess the conservation status of this species and the impacts of increasing human stressors in freshwater ecosystems. Photo-identifications of Inia dolphins were collected between February 2007 and August 2009 in two locations of the Colombian Amazon and Orinoco river basins. Population sizes of Inia were obtained by using the closed (Petersen) mark-recapture model on photo-identifications. The total population size estimate for right/left side individuals was 129/71 Inia dolphins (CV=0.36/0.35) in the Amazon location and 125/58 Inia dolphins (CV=0.77/0.69) in the Orinoco location. The survey and analysis protocols were designed to try to meet mark-recapture assumptions. However, photo-identification was incomplete in both study areas, and there could be recruitment and unequal probabilities of capture due to preferences of individuals for certain areas. Further effort should be focused towards expanding the photo-identification catalogues and creating long-term monitoring programs.

The closed-subpopulation method and estimation of population size from mark-recapture and ancillary data

2000 ◽  
Vol 78 (2) ◽  
pp. 320-326 ◽  
Author(s):  
Frank AM Tuyttens
Keyword(s):  
Population Size ◽  
Ancillary Data ◽  
Mark Recapture ◽  
Animal Populations ◽  
Accuracy And Precision ◽  
Population Size Estimates ◽  
Minimum Number ◽  
Flexible Framework ◽  
And Performance ◽  
Better Than

The algebraic relationships, underlying assumptions, and performance of the recently proposed closed-subpopulation method are compared with those of other commonly used methods for estimating the size of animal populations from mark-recapture records. In its basic format the closed-subpopulation method is similar to the Manly-Parr method and less restrictive than the Jolly-Seber method. Computer simulations indicate that the accuracy and precision of the population estimators generated by the basic closed-subpopulation method are almost comparable to those generated by the Jolly-Seber method, and generally better than those of the minimum-number-alive method. The performance of all these methods depends on the capture probability, the number of previous and subsequent trapping occasions, and whether the population is demographically closed or open. Violation of the assumption of equal catchability causes a negative bias that is more pronounced for the closed-subpopulation and Jolly-Seber estimators than for the minimum-number-alive. The closed-subpopulation method provides a simple and flexible framework for illustrating that the precision and accuracy of population-size estimates can be improved by incorporating evidence, other than mark-recapture data, of the presence of recognisable individuals in the population (from radiotelemetry, mortality records, or sightings, for example) and by exploiting specific characteristics of the population concerned.

Estimation of Catchabilities and Population Sizes of Lobsters

1963 ◽  
Vol 20 (1) ◽  
pp. 59-88 ◽  
Author(s):  
J. E. Paloheimo
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Atlantic Coast ◽  
Temperature Data ◽  
New Method ◽  
Bottom Temperature ◽  
Population Size Estimates ◽  
Population Sizes ◽  
Estimate Population Size ◽  
Size Estimates

Techniques of estimating population size, level of fishing, and the degree of dependence of fishing success on environmental factors are examined on the basis of tagging, catch and effort data. A new method is developed to estimate population size from catch, effort, and temperature data when the catchability varies with temperature.The methods of estimation discussed are applied to data collected from a number of lobster fisheries on Canada's Atlantic coast. Analysis confirms a relationship between the catchability of lobsters and bottom temperature. Differences in this relationship are found between areas and between tagged and untagged lobsters within areas. It is suggested that these differences are attributable to the differences in densities as well as to aggregations of lobsters and fishing. The effect of these aggregations on population size estimates is considered.Calculated average catchabilities at comparable temperatures are different for different areas. These differences are correlated with the numbers of trap hauls per day per square miles fished. It is suggested that the differences in the catchabilities might be due to interactions between units of gear not predicted by the customary relationship between catch and effort.

Fish population size estimates from a small intermittently open estuary in South Africa, based on mark-recapture techniques

2001 ◽  
Vol 52 (3) ◽  
pp. 283 ◽  
Author(s):  
P. D. Cowley ◽  
A. K. Whitfield
Keyword(s):  
Population Size ◽  
Total Population ◽  
Fish Population ◽  
Minimum Size ◽  
Population Estimates ◽  
Likelihood Estimator ◽  
Mark Recapture ◽  
Population Size Estimates ◽  
Population Sizes ◽  
Size Estimates

Population sizes of the migratory marine-spawning fishes in the small intermittently open East Kleinemonde Estuary (33º32′S, 27º03′E) were estimated during two independent mark–recapture studies between 1994 and 1996. Seines were used to sample fishes during the closed-mouth phase of the estuary. All individuals above a stipulated minimum size were marked by fin-clipping. Population estimates were obtained by use of two mark–recapture models (Schnabel and a maximum-likelihood estimator) and a derived method. The total population size was estimated at ~18 000 and ~133 000 individuals during the two study periods respectively. The large temporal (interannual) variability was ascribed to both abiotic (estuary mouth conditions) and biotic-conditions. The dominant species during both periods was Rhabdosargus holubi, which accounted for ~75% and ~80%of the total population of marine fishes in the estuary. The success of this species is attributed to an extended breeding season and the ability to recruit during mouth overwash events.

scholarly journals Effects of Social Organization, Trap Arrangement and Density, Sampling Scale, and Population Density on Bias in Population Size Estimation Using Some Common Mark-Recapture Estimators

2017 ◽  
Author(s):  
Manan Gupta ◽  
Amitabh Joshi ◽  
T. N. C. Vidya
Keyword(s):  
Population Density ◽  
Social Organization ◽  
Population Size ◽  
Robust Design ◽  
Population Size Estimation ◽  
Size Estimation ◽  
Mark Recapture ◽  
Social Species ◽  
Population Size Estimates ◽  
Size Estimates

AbstractMark-recapture estimators are commonly used for population size estimation, and typically yield unbiased estimates for most solitary species with low to moderate home range sizes. However, these methods assume independence of captures among individuals, an assumption that is clearly violated in social species that show fission-fusion dynamics, such as the Asian elephant. In the specific case of Asian elephants, doubts have been raised about the accuracy of population size estimates. More importantly, the potential problem for the use of mark-recapture methods posed by social organization in general has not been systematically addressed. We developed an individual-based simulation framework to systematically examine the potential effects of type of social organization, as well as other factors such as trap density and arrangement, spatial scale of sampling, and population density, on bias in population sizes estimated by POPAN, Robust Design, and Robust Design with detection heterogeneity. In the present study, we ran simulations with biological, demographic and ecological parameters relevant to Asian elephant populations, but the simulation framework is easily extended to address questions relevant to other social species. We collected capture history data from the simulations, and used those data to test for bias in population size estimation. Social organization significantly affected bias in most analyses, but the effect sizes were variable, depending on other factors. Social organization tended to introduce large bias when trap arrangement was uniform and sampling effort was low. POPAN clearly outperformed the two Robust Design models we tested, yielding close to zero bias if traps were arranged at random in the study area, and when population density and trap density were not too low. Social organization did not have a major effect on bias for these parameter combinations at which POPAN gave more or less unbiased population size estimates. Therefore, the effect of social organization on bias in population estimation could be removed by using POPAN with specific parameter combinations, to obtain population size estimates in a social species.

Estimating the population size of people who inject drugs in Ho Chi Minh City, Vietnam: A two-survey capture-recapture exercise (Preprint)

2019 ◽  
Author(s):  
Abu Abdul-Quader
Keyword(s):  
Population Size ◽  
Illicit Drugs ◽  
People Who Inject Drugs ◽  
Care Service ◽  
Ho Chi Minh City ◽  
Size Estimation ◽  
Population Size Estimates ◽  
Capture Recapture ◽  
The City ◽  
Size Estimates

BACKGROUND Population size estimation of people who inject drugs (PWID) in Ho Chi Minh City (HCMC), Vietnam relied on the UNAIDS Estimation and Projection Package and reports from the city police department. The two estimates vary widely. OBJECTIVE To estimate the population size of people who inject drugs in Ho Chi Minh City, Vietnam METHODS Using Respondent-driven sampling (RDS), we implemented two-source capture-recapture method to estimate the population size of PWID in HCMC in 2017 in 7 out of 24 districts. The study included men or women aged at least 18 years who reported injecting illicit drugs in the last 90 days and who had lived in the city the past six months. We calculated two sets of size estimates, the first assumed that all participants in each survey round resided in the district where the survey was conducted, the second, used the district of residence as reported by the participant. District estimates were summed to obtain an aggregate estimate for the seven districts. To calculate the city total, we weighted the population size estimates for each district by the inverse of the stratum specific sampling probabilities. RESULTS The first estimate resulted in a population size of 19,155 (95% CI: 17,006–25,039). The second one generated a smaller population size estimate of 12,867 (95% CI: 11,312–17,393). CONCLUSIONS The two-survey capture-recapture exercise provided two disparate estimates of PWID in HCMC. For planning HIV prevention and care service needs among PWID in HCMC, both estimates may need to be taken into consideration together with size estimates from other sources.

scholarly journals Microsatellite Development and First Population Size Estimates for the Groundwater Isopod Proasellus walteri

PLoS ONE ◽  
2013 ◽  
Vol 8 (9) ◽  
pp. e76213 ◽  
Author(s):  
Cécile Capderrey ◽  
Bernard Kaufmann ◽  
Pauline Jean ◽  
Florian Malard ◽  
Lara Konecny-Dupré ◽  
...  
Keyword(s):  
Population Size ◽  
Microsatellite Development ◽  
Population Size Estimates ◽  
Size Estimates

scholarly journals Estimating population size of the cave shrimp Troglocaris anophthalmus (Crustacea, Decapoda, Caridea) using mark–release–recapture data

2015 ◽  
Vol 38 (1) ◽  
pp. 77-86
Author(s):  
J. Jugovic ◽  
◽  
E. Praprotnik ◽  
E. V. Buzan ◽  
M. Luznik ◽  
...  
Keyword(s):  
Population Size ◽  
Aquatic Invertebrates ◽  
Anthropogenic Activities ◽  
Age Distribution ◽  
Mark Release Recapture ◽  
Population Size Estimates ◽  
Cave Ecosystems ◽  
Size Estimates ◽  
Abundant Population ◽  
Population Numbers

Population size estimates are lacking for many small cave–dwelling aquatic invertebrates that are vulnerable to groundwater contamination from anthropogenic activities. Here we estimated the population size of freshwater shrimp Troglocaris anophthalmus sontica (Crustacea, Decapoda, Caridea) based on mark–release–recapture techniques. The subspecies was investigated in Vipavska jama (Vipava cave), Slovenia, with estimates of sex ratio and age distribution. A high abundance of shrimps was found even after considering the lower limit of the confidence intervals. However, we found no evidence of differences in shrimp abundances between summer and winter. The population was dominated by females. Ease of capture and abundant population numbers indicate that these cave shrimps may be useful as a bioindicator in cave ecosystems.

scholarly journals Unbiased estimation of linkage disequilibrium from unphased data

2019 ◽  
Author(s):  
Aaron P. Ragsdale ◽  
Simon Gravel
Keyword(s):  
Linkage Disequilibrium ◽  
Population Size ◽  
Evolutionary History ◽  
Unbiased Estimation ◽  
Sequencing Data ◽  
Unbiased Estimators ◽  
Population Size Estimates ◽  
Wide Range ◽  
The Common ◽  
Size Estimates

AbstractLinkage disequilibrium is used to infer evolutionary history and to identify regions under selection or associated with a given trait. In each case, we require accurate estimates of linkage disequilibrium from sequencing data. Unphased data presents a challenge because the co-occurrence of alleles at different loci is ambiguous. Commonly used estimators for the common statistics r2 and D2 exhibit large and variable upward biases that complicate interpretation and comparison across cohorts. Here, we show how to find unbiased estimators for a wide range of two-locus statistics, including D2, for both single and multiple randomly mating populations. These provide accurate estimates over three orders of magnitude in LD. We also use these estimators to construct an estimator for r2 that is less biased than commonly used estimators, but nevertheless argue for using rather than r2 for population size estimates.

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