An Assessment of the Geographic Closure Assumption in Mark–Recapture Abundance Estimates of Anadromous Steelhead Populations

2017 ◽  
Vol 37 (5) ◽  
pp. 951-961 ◽  
Author(s):  
Gus Wathen ◽  
Nicholas Weber ◽  
Stephen Bennett ◽  
Nicolaas Bouwes ◽  
Chris E. Jordan
Keyword(s):  
Mark Recapture ◽  
Abundance Estimates ◽  
Closure Assumption

Net-avoidance behaviour in platypuses

2013 ◽  
Vol 35 (2) ◽  
pp. 245 ◽  
Author(s):  
Josh Griffiths ◽  
Tom Kelly ◽  
Andrew Weeks
Keyword(s):  
Acoustic Telemetry ◽  
Direct Evidence ◽  
Avoidance Behaviour ◽  
Mark Recapture ◽  
Abundance Estimates ◽  
Ornithorhynchus Anatinus

It has been suggested that platypuses (Ornithorhynchus anatinus) may avoid nets following capture, compromising abundance estimates using mark–recapture models. Here, we present the first direct evidence of net avoidance behaviour by the platypus. Using acoustic telemetry, we record a platypus bypassing several nets following capture. Understanding variation in capture probabilities will lead to better estimation of platypus abundance, which is currently lacking.

scholarly journals Evaluation of Long-Term Mark-Recapture Data for Estimating Abundance of Juvenile Fall-Run Chinook Salmon on the Stanislaus River from 1996 to 2017

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Tyler Pilger ◽  
Matthew Peterson ◽  
Dana Lee ◽  
Andrea Fuller ◽  
Doug Demko
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Estimation Method ◽  
Central Valley ◽  
Mark Recapture ◽  
Important Species ◽  
Trap Efficiency ◽  
Monitoring Programs ◽  
Abundance Estimates

Conservation and management of culturally and economically important species rely on monitoring programs to provide accurate and robust estimates of population size. Rotary screw traps (RSTs) are often used to monitor populations of anadromous fish, including fall-run Chinook Salmon (Oncorhynchus tshawytscha) in California’s Central Valley. Abundance estimates from RST data depend on estimating a trap's efficiency via mark-recapture releases. Because efficiency estimates are highly variable and influenced by many factors, abundance estimates can be highly uncertain. An additional complication is the multiple accepted methods for how to apply a limited number of trap efficiency estimates, each from discrete time-periods, to a population’s downstream migration, which can span months. Yet, few studies have evaluated these different methods, particularly with long-term monitoring programs. We used 21 years of mark-recapture data and RST catch of juvenile fall-run Chinook Salmon on the Stanislaus River, California, to investigate factors associated with trap efficiency variability across years and mark-recapture releases. We compared annual abundance estimates across five methods that differed in treatment of trap efficiency (stratified versus modeled) and statistical approach (frequentist versus Bayesian) to assess the variability of estimates across methods, and to evaluate whether method affected trends in estimated abundance. Consistent with short-term studies, we observed negative associations between estimated trap efficiency and river discharge as well as fish size. Abundance estimates were robust across all methods, frequently having overlapping confidence intervals. Abundance trends, for the number of increases and decreases from year to year, did not differ across methods. Estimated juvenile abundances were significantly related to adult escapement counts, and the relationship did not depend on estimation method. Understanding the sources of uncertainty related to abundance estimates is necessary to ensure that high-quality estimates are used in life cycle and stock-recruitment modeling.

scholarly journals A novel approach for estimating densities of secretive species from road-survey and spatial-movement data

2018 ◽  
Vol 45 (5) ◽  
pp. 446 ◽  
Author(s):  
John D. Willson ◽  
Shannon E. Pittman ◽  
Jeffrey C. Beane ◽  
Tracey D. Tuberville
Keyword(s):  
North Carolina ◽  
Radio Telemetry ◽  
Model Parameters ◽  
Vehicle Speed ◽  
Mark Recapture ◽  
Snake Species ◽  
The North ◽  
Abundance Estimates ◽  
Spatial Movement ◽  
Road Survey

Context Accurate estimates of population density are a critical component of effective wildlife conservation and management. However, many snake species are so secretive that their density cannot be determined using traditional methods such as capture–mark–recapture. Thus, the status of most terrestrial snake populations remains completely unknown. Aim We developed a novel simulation-based technique for estimating density of secretive snakes that combined behavioural observations of snake road-crossing behaviour (crossing speed), effort-corrected road-survey data, and simulations of spatial movement patterns derived from radio-telemetry, without relying on mark–recapture. Methods We used radio-telemetry data to parameterise individual-based movement models that estimate the frequency with which individual snakes cross roads and used information on survey vehicle speed and snake crossing speed to determine the probability of detecting a snake, given that it crosses the road transect during a survey. Snake encounter frequencies during systematic road surveys were then interpreted in light of detection probabilities and simulation model results to estimate snake densities and to assess various factors likely to affect abundance estimates. We demonstrated the broad applicability of this approach through a case study of the imperiled southern hognose snake (Heterodon simus) in the North Carolina (USA) Sandhills. Key results We estimated that H. simus occurs at average densities of 0.17 ha–1 in the North Carolina Sandhills and explored the sensitivity of this estimate to assumptions and variation in model parameters. Conclusions Our novel method allowed us to generate the first abundance estimates for H. simus. We found that H. simus exists at low densities relative to congeners and other mid-sized snake species, raising concern that this species may not only have declined in geographic range, but may also occur at low densities or be declining in their strongholds, such as the North Carolina Sandhills. Implications We present a framework for estimating density of species that have traditionally been considered too secretive to study at the population level. This method will greatly enhance our ability to study and manage a wide variety of snake species and could be applied to other secretive wildlife species that are most frequently encountered during road surveys.

Integrating Acoustic Telemetry into a Mark–Recapture Model to Improve Catchability Parameters and Abundance Estimates of Lake Sturgeon in Eastern Lake Erie

2019 ◽  
Vol 39 (5) ◽  
pp. 913-920
Author(s):  
Jonah L. Withers ◽  
Donald Einhouse ◽  
Michael Clancy ◽  
Lori Davis ◽  
Rachel Neuenhoff ◽  
...  
Keyword(s):  
Acoustic Telemetry ◽  
Lake Erie ◽  
Lake Sturgeon ◽  
Mark Recapture ◽  
Abundance Estimates

Integrating acoustic telemetry into mark–recapture models to improve the precision of apparent survival and abundance estimates

Oecologia ◽  
2015 ◽  
Vol 178 (3) ◽  
pp. 761-772 ◽  
Author(s):  
Christine L. Dudgeon ◽  
Kenneth H. Pollock ◽  
J. Matias Braccini ◽  
Jayson M. Semmens ◽  
Adam Barnett
Keyword(s):  
Acoustic Telemetry ◽  
Apparent Survival ◽  
Mark Recapture ◽  
Abundance Estimates

Evaluating mark - recapture sampling designs for fish in an open riverine system

2011 ◽  
Vol 62 (7) ◽  
pp. 835 ◽  
Author(s):  
Daniel C. Gwinn ◽  
Paul Brown ◽  
Jakob C. Tetzlaff ◽  
Mike S. Allen
Keyword(s):  
Open Systems ◽  
Monitoring Program ◽  
Sampling Area ◽  
Mark Recapture ◽  
Closed Population ◽  
Management Objectives ◽  
Monitoring Programs ◽  
Abundance Estimates ◽  
Simulation Results ◽  
Murray Cod

Sampling designs for effective monitoring programs are often specific to individual systems and management needs. Failure to carefully evaluate sampling designs of monitoring programs can lead to data that are ineffective for informing management objectives. We demonstrated the use of an individual-based model to evaluate closed-population mark–recapture sampling designs for monitoring fish abundance in open systems, using Murray cod (Maccullochella peelii (Mitchell, 1838)) in the Murray–Darling River basin, Australia, as an example. The model used home-range, capture-probability and abundance estimates to evaluate the influence of the size of the sampling area and the number of sampling events on bias and precision of mark–recapture abundance estimates. Simulation results indicated a trade-off between the number of sampling events and the size of the sampling reach such that investigators could employ large sampling areas with relatively few sampling events, or smaller sampling areas with more sampling events to produce acceptably accurate and precise abundance estimates. The current paper presents a framework for evaluating parameter bias resulting from migration when applying closed-population mark–recapture models to open populations and demonstrates the use of simulation approaches for informing efficient and effective monitoring-program design.

scholarly journals Incorporating antenna detections into abundance estimates of fish

2021 ◽  
Author(s):  
Maria C. Dzul ◽  
Charles B. Yackulic ◽  
William Louis Kendall ◽  
Dana L Winkelman ◽  
Mary M. Conner ◽  
...  
Keyword(s):  
Field Data ◽  
Abundance Estimation ◽  
Data Sets ◽  
Simulation Studies ◽  
Pit Tag ◽  
Mark Recapture ◽  
Passive Integrated Transponder ◽  
Fish Size ◽  
Abundance Estimates ◽  
State Uncertainty

Autonomous passive integrated transponder (PIT) tag antennas are commonly used to detect fish marked with PIT tags but cannot detect unmarked fish, creating challenges for abundance estimation. Here we describe an approach to estimate abundance from paired physical capture and antenna detection data in closed and open mark-recapture models. Additionally, for open models, we develop an approach that incorporates uncertainty in fish size, because fish size changes through time (as fish grow bigger) but is unknown if fish are not physically captured (e.g., only detected on antennas). Incorporation of size uncertainty allows for estimation of size-specific abundances and demonstrates a generally useful method for obtaining state-specific abundances estimates under state uncertainty. Simulation studies comparing models with and without antenna detections illustrate that the benefit of our approach increases as a larger proportion of the population is marked. When applied to two field data sets, our approach to incorporating antenna detections reduced uncertainty in abundance substantially. We conclude that PIT antennas hold great potential for improving abundance estimation, despite the challenges they present.

A robust baseline for bottlenose dolphin abundance in coastal Moreton Bay: a large carnivore living in a region of escalating anthropogenic impacts

2008 ◽  
Vol 35 (7) ◽  
pp. 593 ◽  
Author(s):  
Vimoksalehi Lukoschek ◽  
B. Louise Chilvers
Keyword(s):  
Bottlenose Dolphin ◽  
Anthropogenic Impacts ◽  
Bottlenose Dolphins ◽  
Estimation Methods ◽  
Line Transect ◽  
Mark Recapture ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Moreton Bay ◽  
Abundance Estimates

Marine megafauna populations in coastal waters are increasingly threatened by anthropogenic impacts. Moreton Bay, a large embayment in south-east Queensland, lies adjacent to one of the fastest growing regions in Australia and has a resident population of bottlenose dolphins, Tursiops aduncus. Evaluation of the effectiveness of any proposed management strategy requires robust population abundance estimates. We estimated abundances of bottlenose dolphins in central eastern Moreton Bay (350 km2) using two commonly used abundance estimation methods for cetaceans: photo-identification mark–recapture and line-transect surveys. Mark–recapture data were analysed in CAPTURE using a model that allowed capture probabilities to vary between sampling events and between individuals. Based on an estimated 76% of the population identifiable photographically, total abundance estimates were 673 ± 130 s.e. (1997) and 818 ± 152 s.e. (1998). Line-transect data, analysed using DISTANCE, gave an abundance estimate of 407 ± 113.5 s.e. (2000). These abundance estimates are large compared with many other coastal bottlenose dolphin populations. The line-transect surveys comprised a pilot study, and the lower line-transect abundance estimate is probably best attributable to methodological issues. In particular, smaller mean group size was estimated for the line-transects surveys (2.85 ± 0.29 s.e.) than the mark–recapture surveys (4.87 ± 0.39 s.e., 1997; 5.78 ± 0.73 s.e., 1998), and line-transect group sizes were probably underestimated. In addition, the line-transect detection probability (g(o)) was assumed to be one but was almost certainly less than one. However, the possibility of an actual decline in population size cannot be ruled out. Coefficients of variation (CV) were lower for mark–recapture than for line-transect surveys, however, CVs of line-transect estimates could be lowered through improved survey design. We evaluated the power of these surveys to detect trends in potential population declines for bottlenose dolphins in Moreton Bay and make recommendations for ongoing monitoring strategies.

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