Tag Loss Rates Research Articles

Mark-recapture validates the use of photo-identification for the widely distributed blue-spotted ribbontail ray, Taeniura lymma

The ability to identify individual animals can provide valuable insights into the behaviour, life history, survivorship, and demographics of wild populations. Photo-identification (photo-ID) uses unique natural markings to identify individuals and can be effective for scalable and non-invasive research on marine fauna. The successful application of photo-ID requires that chosen distinguishing markings are unique to individuals and persist over time. In this study, we validate the use of dorsal spot patterns for identifying individual blue-spotted ribbontail rays (Taeniura lymma) in conjunction with traditional tagging methods. Spot patterns were unique among T. lymma with 90.3% of individuals correctly identified using I3S photo-matching software from images taken up to 496 days apart. In comparison, traditional physical tagging methods showed a tag loss rate of 27% and a maximum tag retention period of only 356 days. Our findings demonstrate the effectiveness of photo-ID as a tool to monitor populations and better understand the ecology of the blue-spotted ribbontail ray without the need for physical tagging. The validation of photo-ID for this widespread species is important as it enables behavioural and demographic changes to be easily tracked in relation to coastal threats such as human development and habitat degradation.

Single molecule infrared spectroscopy in the gas phase

Spectroscopy is a key analytical tool that provides valuable insight into molecular structure and is widely used to identify chemical samples. Tagging spectroscopy is a form of action spectroscopy in which the absorption of a single photon by a molecular ion is detected via the loss of a weakly attached, inert ‘tag’ particle (for example, He, Ne, N2)1–3. The absorption spectrum is derived from the tag loss rate as a function of incident radiation frequency. So far, all spectroscopy of gas phase polyatomic molecules has been restricted to large molecular ensembles, thus complicating spectral interpretation by the presence of multiple chemical and isomeric species. Here we present a novel tagging spectroscopic scheme to analyse the purest possible sample: a single gas phase molecule. We demonstrate this technique with the measurement of the infrared spectrum of a single gas phase tropylium (C7H7+) molecular ion. The high sensitivity of our method revealed spectral features not previously observed using traditional tagging methods4. Our approach, in principle, enables analysis of multicomponent mixtures by identifying constituent molecules one at a time. Single molecule sensitivity extends action spectroscopy to rare samples, such as those of extraterrestrial origin5,6, or to reactive reaction intermediates formed at number densities that are too low for traditional action methods.

The impacts of marking on bats: mark-recapture models for assessing injury rates and tag loss

AbstractThe individual identification of animals is essential for long-term population ecology studies. Injuries and tag loss can negatively impact animal welfare and parameter estimates. We used time-to-failure curves and multistate mark-recapture models to estimate injury rates, body condition decline, tag loss and survival probabilities associated with two tags commonly used in bats: metallic arm bands and steel ball chain collars. We monitored two colonies of Carollia perspicillata at União Biological Reserve, southeastern Brazil, from 2013 to 2019. Every other month, we marked individuals with arm bands, collars or both. Collars did not cause noticeable injuries, but were lost at a higher rate than arm bands (1.5–2.5 times). The arm band-related injury probability between captures was ~ 0.2, and after 17 months half the marked animals developed injuries. Animals marked as juveniles were less likely to get injured than adults. Injuries were associated with a lower body condition in females. Body condition was positively associated with apparent survival; however, a direct effect of arm band injuries on survival estimates was not observed. The tag loss rates caused a negative bias in survival estimates. Mark-recapture studies should evaluate the efficacy of the marking technique, accounting for potential animal injury, tag loss, and bias in parameter estimation. Marking individuals should be limited to studies that monitor species with high recapture probability, using the least harmful tags possible, and balancing the burden to the animals with the potential to generate knowledge.

Sentinels in Salmon Aquaculture: Heart Rates Across Seasons and During Crowding Events.

Advances in tag technology now make it possible to monitor the behavior of small groups of individual fish as bioindicators of population wellbeing in commercial aquaculture settings. For example, tags may detect unusual patterns in fish heart rate, which could serve as an early indicator of whether fish health or welfare is becoming compromised. Here, we investigated the use of commercially available heart rate biologgers implanted into 24 Atlantic salmon weighing 3.6 ± 0.8 kg (mean ± SD) to monitor fish over 5 months in a standard 12 m × 12 m square sea cage containing ∼6,000 conspecifics. Post tagging, fish established a diurnal heart rate rhythm within 24 h, which stabilized after 4 days. Whilst the registered tagged fish mortality over the trial period was 0%, only 75% of tagged fish were recaptured at harvest, resulting in an unexplained tag loss rate of 25%. After 5 months, tagged fish were approximately 20% lighter and 8% shorter, but of the similar condition when compared to untagged fish. Distinct diurnal heart rate patterns were observed and changed with seasonal day length of natural illumination. Fish exhibited lower heart rates at night [winter 39 ± 0.2 beats per min (bpm), spring 37 ± 0.2 bpm, summer 43 ± 0.3 bpm, mean ± SE] than during the day (winter 50 ± 0.3 bpm, spring 48 ± 0.2 bpm, summer 49 ± 0.2 bpm) with the difference between night and day heart rates near half during the summer (6 bpm) compared to winter and spring (both 11 bpm). When fish experienced moderate and severe crowding events in early summer, the highest hourly heart rates reached 60 ± 2.5 bpm and 72 ± 2.4 bpm, respectively, on the day of crowding. Here, if the negative sublethal effects on fish that carry tags (e.g., growth rate) can be substantially reduced, the ability to monitor diurnal heart rate patterns across seasons and detect changes during crowding events, and using heart rate biologgers could be a useful warning mechanism for detecting sudden changes in fish behavior in sea cages.

Operculum PIT tagging: a viable alternative to avoid human consumption in processed salmon

BackgroundPassive integrated transponder (PIT) tags are commonly used to identify individual fish. However, use of PIT tags in commercial aquaculture research is limited by consumer safety concerns. For farmed fish, it is critical that tags do not end up in the final product. One possibility to enable the use of PIT tags in commercial research is to insert tags into a part of the body that will be separated from the trunk during processing. We compare tag loss, mortality rate and welfare scores between Atlantic salmon post-smolts (n = 798) marked with PIT tags either in the operculum musculature or the abdominal cavity (standard practice) before and after mechanical delousing.ResultsWe found that neither condition factor (K) (range 0.60–1.99) nor tagging location significantly affected tag loss (operculum = 6%, intraperitoneal = 8%, z = 1.46, p = 0.14) or mortality (operculum = 2%, intraperitoneal = 2%, z = 0.55, p = 0.58). However, on average, the fish which died weighed 20% less at the time of handling (271 ± 13 g, K = 1.12 ± 0.02) than those which survived (340 ± 3 g, K = 1.14 ± 0.004), and those which lost tags (291 ± 7 g, K = 1.11 ± 0.02) weighed 15% less than those which retained them (340 ± 3 g, K = 1.14 ± 0.004), irrespective of tagging location or handling treatment.ConclusionsFish tagged in the operculum musculature had comparable rates of mortality and tag loss to the current “best practice” standard of intraperitoneal tagging. We show that placement of PIT tags in operculum musculature is a viable alternative to placement in the peritoneal cavity.

Low Rates of PIT‐Tag Loss in an Insectivorous Bat Species

ABSTRACTThe rate of loss of tags used to mark individuals is an important consideration in wildlife research and monitoring. Passive integrated transponder (PIT) tags (or microchips) generally have high retention rates; however, tag loss rates for small mammals such as insectivorous bats are poorly understood. We double‐marked a population of Gould's wattled bats (Chalinolobus gouldii) with forearm bands and PIT tags (with the injection site sealed with surgical adhesive) in January and February 2020 to determine rates of subsequent tag loss over the short‐ (1–2 months) and medium‐ (13–14 months) term. Loss of PIT tags occurred in 4 (2.7%) of 146 recaptured individuals, all within 2 months of microchipping. We also recorded 1 occurrence of band loss 11 months after banding. Our study supports assertions that PIT‐tag retention rates in small mammals are high, and suggests that rates of tag loss in small bat species are low when surgical adhesive is applied. Quantifying the rate of tag loss enables this variable to be incorporated into mark‐recapture models. © 2021 The Wildlife Society.

A PIT‐tag–based method for measuring individual bait uptake in small mammals

Abstract Rodents and other small mammals cause an increasing number of negative economic and environmental impacts worldwide. In the UK, the non‐native grey squirrel has a significant impact on the forestry industry and has caused the decline of the native red squirrel. Baits are used to deliver biocides and contraceptives to reduce overabundant wildlife populations and as vehicles for vaccines to control disease outbreaks. Bait‐delivered contraceptives are also being developed to manage grey squirrel populations in the UK. The effectiveness of bait‐delivered drugs on wildlife populations depends on the amount of bait consumed by individuals over time; therefore, it is important to understand individual level bait uptake in order to optimize delivery methods. Passive integrated transponder (PIT) tags are increasingly used to mark and monitor animal behaviour as they are cost‐effective, have minimal negative welfare impacts and have a lower tag loss rate than external tags, particularly in small animals. The aim of this study was to design and test a novel bait hopper equipped with a PIT‐tag reader and bait‐weighing device, to record bait uptake by individual grey squirrels for optimizing the delivery of a contraceptive bait. The hopper was designed to overcome some of the limitations of traditional PIT‐tag systems, by improving battery life and the quality and quantity of data collected in the field. In captive trials, the hopper proved to be highly effective at recording feeding visits by squirrels, as 95% of the visits could be attributed to a PIT‐tag record. The hoppers measured the amount of bait removed per feeding visit to an accuracy of 0.1 g, with 97% of the bait taken from six hoppers attributed to a PIT‐tag ID. In a field trial, the hoppers were effective at recording the feeding visits by grey squirrels in two woods, with 47 of the 51 PIT‐tagged grey squirrels entering the hoppers. The adaptability of the hopper design means that it has wider applications for wildlife management; in particular, efficacy studies for bait‐delivered substances in the context of wildlife disease control and/or population reduction.

Estimating growth, size-dependent mortality, and tag loss in a mark-recapture study: demography of wavy turban snails in Southern California, USA

Tagging studies are often used to measure survival and growth in wild populations. However, issues such as low returns of tagged animals, tag loss, and handling mortality can affect the precision and accuracy of demographic estimates if not accounted for. We conducted a mark-recapture study to measure the survival and growth of juvenile and adult wavy turban snails Megastraea undosa. Our study highlights several methodological advances, including a method for estimating a single growth function by analyzing the joint changes in length and weight of tagged animals; a simple method for estimating rates of tag loss when some animals are double tagged; and a way to estimate handling mortality by comparing encounter histories of animals immediately after tagging and after several weeks in the field. Tag loss was moderate (≈15% over a 100 d period) and handling mortality was substantial during the fall (≈55%), but negligible during the spring. If we did not account for tag loss and handling mortality, our estimate of survival would have been severely underestimated (≈46% lower over a 100 d period). After accounting for such effects, our study revealed that survival probably increased sharply with body size, but survival did not differ among seasons. These snails are slow-growing, mature after approximately 6 yr, and can routinely grow to >10 yr old. There is an emerging fishery for this species, and because our results suggest that the oldest snails have a very high reproductive value, measures that protect these large individuals are likely to be beneficial for the resilience of these populations.

Long-term retention of dummy acoustic transmitters in adult brown trout.

A group of 36 1+ age class Salmo trutta were surgically implanted with dummy acoustic tags and monitored for 370 days. In total 13 tags were expelled throughout the experiment with an overall tag loss rate of c. 0.035 tags per day. Fish length was the only explanatory variable which had a significant association with subsequent tag expulsion. The estimated probability of retaining a tag for a year for a fish of length 32 cm was 0.76, 34 cm was 0.60 and 36 cm was 0.38. The long-term tag loss patterns were examined and discussed.

Suitability of surgically implanted 8‐mm passive integrated transponder tags for small‐bodied fishes

Innovative tools that benefit conservation are critical as freshwater fishes are lost at unprecedented rates. Mark-recapture methods can characterize population demographics and life-history traits of diverse fishes, but suitable techniques for tagging for individual recognition of small-bodied fishes are rare. Passive integrated transponder (PIT) tag technology may facilitate the tagging of small fishes and early life stages of larger species. However, relatively little research has evaluated the suitability of these small (8.4 × 1.4 mm) tags for many groups of small fishes. Tag loss (retention and survival) and growth of individuals implanted with PIT tags relative to control and sham treatments were compared for eight fishes of differing morphologies. Additionally, the utility of cyanoacrylate to improve tag retention was tested on a subset of taxa. Fish of each species were equally divided and randomly assigned to one of three treatment groups (handled [control], surgical incision [sham], or surgical incision and PIT tag implantation [PIT]). During the 42-d study period, mortalities and expelled tags were counted daily and growth was measured weekly. Researchers can generally expect little tag loss and uncompromised growth rates for a variety of small-bodied fishes; however, initial fish length was related to the magnitude of physiological effects for some taxa (i.e., blacknose dace Rhinichthys atratulus, johnny darter Etheostoma nigrum, juvenile white sucker Catostomus commersonii). Relatively poor survival (<80%) was observed for two benthic species: johnny darter and blacknose dace, often when incision wounds became inflamed before healing. Prevalent tag loss for johnny darter, tadpole madtom Noturus gyrinus, and a dorsal-laterally compressed cyprinid can be reduced by closing the wounds with cyanoacrylate, but with substantially increased mortality rates. This research demonstrates the broad applicability of PIT tagging technology for ecological studies of small-bodied fishes and alleviates many concerns when surgically implanting tags into several fishes.

Parameter estimation performance of a recapture-conditioned integrated tagging catch-at-age analysis model

Recapture-conditioned models are infrequently used to analyze tag-recovery data, but have been proposed as an alternative to release-conditioned models for estimating movement from tagging studies when tag-loss processes (e.g., tag reporting, tag shedding) can be assumed constant and estimates of these processes are not available. Through simulations, we investigated the performance (bias and precision) of a recapture-conditioned integrated tagging catch-at-age analysis (ITCAAN) that assumes yearly natal homing under varying model complexities and intermixing rates and compared the results to those from a release-conditioned ITCAAN. We also investigated how misspecification of natural mortality, parity in population productivities, tag shedding, and spatially-varying reporting rates affected estimation of model parameters. At low intermixing rates, estimation of total abundance and spawning population abundances was accurate and precise, with precision decreasing when natural mortality was estimated for the recapture-conditioned ITCAAN. Accuracy and precision of individual population abundances declined with higher intermixing rates, with the largest bias and lowest precision occurring when estimating relative reporting rates. Assuming reporting rates were spatially constant in the ITCAAN when they varied regionally in the operating model led to biased estimation of movement rates and population abundances for both ITCAANs; attempting to estimate relative reporting when reporting varied spatially greatly improved parameter estimation compared to assuming spatially constant reporting. When tag shedding was simulated to occur, the recapture-conditioned ITCAAN yielded relatively unbiased estimation of total abundance without additional data on the tag-shedding rate, whereas the release-conditioned ITCAAN requires external data to inform this tag shedding process. Incorrect specification of tag-shedding rates by 20% resulted in only a 5% bias in estimation of total abundance from the release-conditioned ITCAAN. To avoid biased estimation from the release-conditioned model, externally derived data for all tag loss rates (e.g. tag shedding and tag-induced mortality) must be provided to the ITCAAN. Movement rates in the recapture-conditioned ITCAAN framework are theoretically unbiased by spatially uniform loss rates, but yielded biased estimates at high movement rates in this simulation study as a consequence of the model's poor ability to estimate population-specific abundances. For most scenarios investigated, estimation by the release-conditioned ITCAAN was less biased and more precise compared to the estimation by the recapture-conditioned ITCAAN presumably as a consequence of the former providing additional information on region-specific survival. However, both models performed poorly in estimating population specific abundances for scenarios with high intermixing rates and when reporting rates varied regionally but were assumed to be regionally constant in the ITCAANs.

A novel RFID multi-tag anti-collision protocol for dynamic vehicle identification.

In order to obtain the information of the vehicle tags in adverse traffic conditions, we proposed a novel reservation framework named reservation to cancel idle-dynamic frame slotted ALOHA (RTCI-DFSA) algorithm. Firstly, the framework employed reservation mechanism to remove idle slot, and thus improve the system identification efficiency. Secondly, the vehicle information was identified by the tag serialization polling identification method. The experimental results showed that the proposed RTCI-DFSA algorithm performed better than the traditional frame slotted ALOHA (FSA) and dynamic frame slotted ALOHA (DFSA) algorithms. More specifically, the tag loss rate of the proposed framework is significantly lower than the frame length fixed and conventional dynamic vehicle identification algorithms. In addition, the experimental results demonstrated that the throughput rate of the proposed algorithm increased from 0.368 to 0.6. Besides, the identification efficiency and applicability of the proposed framework were both higher than other tag identification algorithms.

Evaluation of Coded Wire Tag Loss in Brook Trout Tagged Using Automated Methods

AbstractAutomated coded‐wire‐tagging methods were recently applied to Brook Trout Salvelinus fontinalis for the first time, but information on tag loss and method efficiency is needed. We observed tag loss in Brook Trout over 210 d posttagging to determine the degree of tag loss and when tag loss stabilized for the 2015 year‐class. We also evaluated tag loss from two subsequent year‐classes. Brook Trout tag loss stabilized (i.e., reached the curve's inflection point) at 1.5% after 15 d posttagging and achieved its asymptotic maximum of 1.6% after 28 d. Tag loss rates for subsequent year‐classes were 1.7% and 2.3%. We also described throughput (fish tagged per hour) to evaluate method efficiency. Throughput ranged from 8,449 to 9,395 fish/h for Brook Trout and was comparable to observations on other salmonines; combined with the low rate of tag loss, this demonstrates the efficacy of automated methods for the marking and tagging of this species. In addition, rapid stabilization of tag loss in Brook Trout (15 d) was similar to that observed in Pacific salmonines but distinct from that recorded for other Salvelinus spp. (≥150 d), and underscored the need to directly measure species‐specific tag loss and its stabilization period and to avoid using closely related species as proxies.

Retention of radiotransmitters tail‐mounted on 6 bird species

ABSTRACTRadiotransmitters can be tail‐mounted using cyanoacrylate glue and an accelerant rather than using a harness. Tail‐mounted transmitters are dropped or shed when the rectrices molt, which may reduce transmitter effects while providing retention times sufficient for most research objectives. However, retention times of tail‐mounted transmitters for birds are insufficiently described, and bias from not following all birds until transmitters are shed has been ignored. We studied transmitter retention of 106 birds of 6 species in the United States of America, 2010–2013, using direct observations and survival modeling based on radiotelemetry tracking. Cox proportional hazard survival models predicted median transmitter retention times from 4 to 53 days, depending on species. Our results suggest that researchers should anticipate premature (i.e., &lt;30 days) tag loss rates from 15% to 38% for adult birds, and adjust permit and funding applications accordingly. However, predicted premature tag loss approached 100% for independent juvenile birds, which frequently appeared to disperse long distances, leading to few or no failure events to inform models. Overall, our results provide guidance for the design of future telemetry studies while demonstrating that tail‐mounting transmitters can yield adequate data for a variety of research objectives. © 2018 The Wildlife Society.

Retention of plastic-tipped dart tags in African tigerfish Hydrocynus vittatus

Estimates of tag retention and tagging-related mortality are essential for mark-recapture experiments. Mortality and tag loss were estimated from 15 tigerfish Hydrocynus vittatus marked using Hallmark model PDL plastic-tipped dart tags released into a 1 730 m2 pond at Kamutjonga Inland Fisheries Institute, Namibia, and inspected bi-monthly for the presence or absence of tags. No mortality was observed during the experiment. All marked fish had lost their tags after 10 months and 50% tag loss was estimated at 3.9 months. The high tag loss rate indicates that PDL plastic-tipped dart tags are not suitable for long-term studies on this species.

Performance of Fast Absorbable Sutures and Histo‐Glue for Closing Incisions in Brown Trout

AbstractTelemetry has become a standard tool in fish research, but tagging methods still need refinement to achieve better results and to improve animal welfare. One of the problems reported from evaluations of surgical implants is unsatisfactory wound closure. Thus, researchers struggle to find better ways to close incisions, typically for tags implanted under field conditions. Problems are regularly encountered when closing incisions with traditional absorbable or nonabsorbable sutures, including decreased growth, slow wound healing, and erythema and necrosis at the suture site. We compared survival, growth, tag expulsion rate, and incision healing among three groups of dummy transmitter‐tagged wild Brown Trout Salmo trutta for which incisions were closed with two types of suture material (absorbable and fast absorbable) and histo‐glue. The tagged fish were kept in seminatural ponds for 20 d. Survival did not differ among groups, but growth of the tagged fish was lower than that of the control group. Histo‐glue gave the best healing but resulted in a high tag loss rate (33%). The fast absorbable sutures did not disappear faster than normal absorbable sutures, and healing and tag loss were similar. The use of fast absorbable sutures may hold potential for improving the procedure and should be further tested.

Impact of two telemetry transmitter implantation incision suturing methods on the physiological state and condition of perch (Perca fluviatilis)

Abstract The aim of this work was to determine the impact on European perch, Perca fluviatilis L. (mean body weight – 78.33 g) of the intraperitoneal implantation of telemetry transmitters using different suturing methods. In the first experiment silk sutures were used (experiment I – group ST), while in the second tissue adhesive was used (experiment II – group GT). Following the procedure, the fish were kept for 42 days in a recirculating system. Differences in growth and condition parameters were only noted in the first week of the experiment. Specimens from group GT had lower values for DGR (daily growth rate) and SGR (specific growth rate), but a higher value for FCR (feed conversion ratio) values. For the hematological parameters, lower values of MCV (mean corpuscular volume) and PLT (blood platelets) were noted in group GT, while for the biochemical parameters, lowered ALP (alkaline phosphatase) activity and Mg (magnesium) concentrations were noted in group ST. In group ST, 33.3% of the specimens loss their tags, while in group GT 77.8% did so. Differences in incision healing were only noted in the second week, when specimens in group ST were observed to have fully closed incisions, while in group GT 50% of the incisions were open. Despite the high percentage of implantation incision healing in both groups, because of the high values of tag loss rate, neither method can be recommended for perch. It might be more effective to use tag with external antennae in this species. The method use for closing implantation incisions also must be improved to eliminate tag shedding.

Spatial Heterogeneity, Variable Rewards, Tag Loss, and Tagging Mortality Affect the Performance of Mark–Recapture Designs to Estimate Exploitation: an Example using Red Snapper in the Northern Gulf of Mexico

AbstractAccurate estimates of exploitation rate are essential to the management of exploited fisheries. Tagging studies are often used to estimate exploitation rates, but the performance of these approaches depends strongly on study design characteristics and the magnitude of assumption violations. We simulated a suite of candidate study designs for 1‐year high‐reward and variable‐reward tagging studies, exploring a range of sample sizes (number of tagged fish), exploitation rates, tagging mortality rates, tag loss rates, proportions of double‐tagged fish, and spatial variation in fish density, tag releases, and fishing effort. We calculated the uncertainty, biases, and reward costs of these candidate study designs to determine the most cost‐effective approach to accurately estimate exploitation rate for Red Snapper Lutjanus campechanus in Alabama waters of the Gulf of Mexico. We also investigated how incorrectly assuming a 100% reporting rate would affect these study results. Our simulations demonstrated that using all high‐reward tags provided more accurate and precise exploitation rate estimates than the variable‐reward approach but only if 100% reporting could be safely assumed. Further, distributing tags uniformly over the study area when the true spatial distribution of the population and fishing pressure varied over that area drastically biased exploitation rate estimates, suggesting that prior knowledge of the population's true spatial distribution over the study area is needed to ensure accurate estimates of exploitation rate. The most cost‐effective study design involved tagging between 400 and 1,600 fish with high‐reward tags, with 40% of the fish double‐tagged, and the tags spatially distributed in the same proportion as the population. However, violation of the 100% reporting rate assumption resulted in a proportional downward bias in the estimated exploitation rate. Simulation studies such as this are critical to ensure that cost‐effective study designs produce accurate and precise estimates of exploitation rate, particularly for high‐value species such as Red Snapper.Received July 13, 2016; accepted February 24, 2017 Published online April 14, 2017

Modified tree‐based identification protocols for solving hidden‐tag problem in RFID systems over fading channels

Hidden-tag problem is one of the most important issues in the implementation of radio-frequency identification (RFID) systems. Due to effects of imperfect wireless channels, RFID tags can be hidden during the identification process by either another tag or an unsuccessful detection. The former is known as the capture effect (CE) while the latter is the detection error (DE). This study newly proposes two modified tree-based identification protocols, namely tweaked binary tree (TBT) and tweaked query tree (TQT), which are able to tackle the hidden-tag problem caused by both the CE and DE. The performance of the proposed TBT and TQT protocols, in terms of the average number of slots required to detect a tag, and the tag-loss rate, is evaluated in comparison with that of previously proposed ones. Computer simulations and numerical results confirm the effectiveness of the proposed protocols.

Assessing tag loss and survival probabilities in green turtles (Chelonia mydas) nesting in Malaysia

The loss of external tags is one of the biggest problems in mark-recapture research. An evaluation of tag loss is therefore required to improve tagging methodology, select appropriate tag types, and accurately estimate population status and dynamics. We estimated tag loss probability of double-tagged green turtles (Chelonia mydas) nesting at Redang Island, Malaysia (05°49′ N 103°00′ E), from 1993–2014. For both titanium and Inconel tags, we found a tag loss pattern with a high initial tag loss rate that decreased to an asymptote near a constant value above zero. The initial tag loss probability for titanium tags was higher than for Inconel tags, and titanium tags were lost earlier than Inconel tags in more individuals when both types of tags were attached. In addition, comparison of the tag loss probability of Inconel tags attached during the period when tagging staff changed every year to that when senior tagging staff were not changed, indicated that lack of consistency in tagging staff affected the application of at least one of two Inconel tags. Estimated tag loss probability was incorporated into a recapture model, and annual survival probability was estimated to be 0.893 (95% confidence interval: 0.857–0.921).