Visible Implant Elastomer Tags Research Articles

Zebrafish Injectable Plastic for Identification Tagging (ZIP IT) for larvae to adults using a fluorescent Visible Implant Elastomer

Distinguishing individuals or small groups is essential for many experiments. The regenerative properties of zebrafish make traditional marking methods for rodent models (e.g., tattoos, tissue clipping) ineffective. Fluorescent Visible Implant Elastomer (VIE) can permanently mark juvenile and adult zebrafish but to date no marking technique has been described for larval stage zebrafish. This protocol, Zebrafish Injectable Plastic for Identification Tagging (ZIP IT), utilizes VIE in zebrafish as early as 2 days post fertilization (dpf) using standard microinjection methods and direct injection using an insulin syringe at one month. Larval zebrafish between 2 and 7 dpf were injected in the dorsal musculature. At one month, retention and visibility of the VIE was observed in 72% of the injected fish with no effect on growth; however, a variable change in mortality was observed, generally higher than the uninjected fish. This demonstrates that VIE can be used in very early stages of fish development, providing the first procedure to track individuals or groups within a larger population. Subcutaneous injection of juvenile zebrafish starting at one month has greater than 99%-mark retention and visibility with very low mortality. The combination of larvae and juvenile VIE injections also provide a powerful tool to track and gather data from marked fish throughout their lifespan.•We present a method for tagging individuals or groups of zebrafish at most life stages (larvae or juvenile/adult) with Visible Implant Elastomer (VIE).•The larvae and juvenile injection procedures can be combined so that an individual fish can be tagged for its entire lifetime. Larvae injections become significantly less visible after one month; however, the fish can be reinjected using the juvenile procedure, thus allowing continuity of the visible mark.•This protocol was empirically built on the “Evaluation of VIE tags in Zebrafish (Danio rerio)” by Hohn and Petrie-Hanson (2013) and expanded to include larvae and a small batch elastomer mixing technique.

Estuarine-Specific Migration of Glass Eels in the Ems Estuary

Understanding recruitment of glass eels in estuaries is crucial for the conservation of the European eel (Anguilla anguilla). However, basic knowledge on estuarine-specific glass eel migration, including in estuarine harbours, is mostly lacking. Therefore, we studied glass eel migration in the Dutch–German Ems estuary and the harbour at Delfzijl (The Netherlands) and tagged glass eels with Visual Implant Elastomer tags (VIE tags). We released 2000 tagged glass eels into the Ems estuary itself and 1000 tagged glass eels into the tidal harbour at Delfzijl. At three estuarine locations, i.e., Delfzijl–Duurswold, Termunterzijl, and Nieuwe Statenzijl, glass eel collectors were strategically placed, each location being progressively situated further upstream in the Ems estuary. Most glass eels (nuntagged = 97,089, ntagged = 74) were caught at Nieuwe Statenzijl, although this location is much further upstream. Lower numbers of glass eels (nuntagged = 1856, n tagged = 31) were caught at Delfzijl–Duurswold and Termunterzijl (nuntagged = 1192, ntagged = 7). Glass eels arrived approximately a week earlier at Nieuwe Statenzijl than at the other two locations, and the migration speed of tagged glass eels was highest at Nieuwe Statenzijl (>2 km/day) and lower (<1 km/day) at Delfzijl–Duurswold. Our study highlights that migration and the resulting potential recruitment of glass eels in estuaries and harbours may vary considerably both spatially and temporally. Further research on estuarine-specific factors that influence glass eel migration, such as the (anthropogenically altered) tidal action and flow, will provide valuable information on what influences glass eel migration in estuaries.

Den-Associated Behavior of Octopus rubescens Revealed by a Motion-Activated Camera Trap System.

Dens are a crucial component of the life history of most shallow water octopuses. However, den usage dynamics have only been explored in a few species over relatively short durations, and Octopus rubescens denning behavior has never been explored in situ. We built four underwater camera traps to observe the behavior of O. rubescens in and around their dens. To distinguish individuals, octopuses were captured and given a unique identifiable visible implant elastomer tag on the dorsal side of their mantle. After being tagged and photographed, each octopus was released back to its original capture site within its original den bottle. The site is unique in that octopuses reside almost exclusively in discarded bottles, therefore aiding in locating and monitoring dens. Motion-activated cameras were suspended in a metal field-of-view above bottle dens of released octopuses to observe den-associated behaviors. Cameras were regularly retrieved and replaced to allow continuous monitoring of den locations in 71 h intervals for over a month. We found that O. rubescenswas primarily active during the day and had frequent interactions with conspecifics (other members within the species). We also found that rockfish and red rock crabs tended to frequent den locations more often when octopuses were not present, while kelp greenling both visited dens more frequently and stayed longer when octopuses were present. Our results, demonstrate the utility of motion-activated camera traps for behavioral and ecological studies of nearshore mobile organisms.

Site fidelity of fish on a rocky intertidal in the south of Portugal

The short-term site fidelity of intertidal fish species was studied in a rocky intertidal zone in southern Portugal using visible implant elastomer tagging. Eleven fish species were caught, tagged and released, seven of which were recaptured. The larger tide pool with the highest complexity level and located at a lower position in the shore level did not have recaptures, while in others the individual fish species recaptured rate ranged from 11.1 to 38.9%, suggesting that the shore height is a dominant factor influencing site fidelity. Although the breeding season seems not to be the only explanation for the recapture rate, the higher mean recapture rates of Parablennius sanguinolentus, Lipophrys pholis and Gobius cobitis may be related to the parental behaviour of these species during that period. Site fidelity of juveniles of Scorpaena porcus in tidepools is reported for the first time, showing the importance of this habitat as a nursery ground.

Evaluation of Tagging Methods for Unique Identification of Individuals in Three Aquatic Eurycea Salamander Species

Marking or tagging salamanders increases efficiencies in the operations and management of captive populations and facilitates techniques for monitoring demographics of wild populations. Tags facilitate monitoring of longitudinal data for individual animals such as age or estimated age, growth, reproduction, and health. We evaluated three different tagging methods on Texas Blind, San Marcos, and Comal Springs Salamanders to determine success of each as a long-term marker of individual animals. For this study, we selected visible implant elastomer (VIE), visible implant alphanumeric tags (VIA), and passive integrated transponders (PIT). Of these, only VIE tagging has been evaluated in San Marcos Salamanders; none have been evaluated for use in the other two salamander species studied; and comparison studies among these tags for fully aquatic salamander species have not been performed. These tag types were selected for their effectiveness with other salamander species, ability to be quickly and easily identified tank-side, minimal negative effects on organisms, and perceived ease of implanting the tags. The VIE tags were retained by all species and had high readability scores. However, the issues of tag breakage and deterioration should be considered when using VIE tags. VIA tags were rejected in all but one San Marcos Salamander and all Comal Springs Salamanders, but 90% of Texas Blind Salamanders retained them. PIT tags were not tested on San Marcos, Comal Springs, and smaller Texas Blind Salamanders due to size of tag and low retention rate in larger salamanders. Of the tags evaluated in this study, VIE was the most effective in terms of retention, readability, and ease of insertion.

Direct and Molecular Observation of Movement and Reproduction by Candy Darter, Etheostoma osburni, an Endangered Benthic Stream Fish in Virginia, USA

Direct and indirect measures of individual movement provide valuable knowledge regarding a species’ resiliency to environmental change. Information on patterns of movement can inform species management and conservation but is lacking for many imperiled fishes. The Candy Darter, Etheostoma osburni, is an endangered stream fish with a dramatically reduced distribution in Virginia in the eastern United States, now known from only four isolated populations. We used visual implant elastomer tags and microsatellite DNA markers to directly describe movement patterns in two populations. Parentage analysis based on parent-offspring pairs was used to infer movement patterns of young-of-year and age-1 individuals, as well as the reproductive contribution of certain adults. Direct measurements of movement distances were generally similar between methods, but microsatellite markers revealed greater distances moved, commensurate with greater spatial frames sampled. Parent-offspring pairs were found throughout the species’ 18.8-km distribution in Stony Creek, while most parent-offspring pairs were in 2 km of the 4.25-km distribution in Laurel Creek. Sibship reconstruction allowed us to characterize the mating system and number of spawning years for adults. Our results provide the first measures of movement patterns of Candy Darter as well as the spatial distribution of parent-offspring pairs, which may be useful for selecting collection sites in source populations to be used for translocation or reintroductions. Our results highlight the importance of documenting species movement patterns and spatial distributions of related individuals as steps toward understanding population dynamics and informing translocation strategies. We also demonstrate that the reproductive longevity of this species is greater than previously described, which may be the case for other small stream fishes.

Standardized microsatellite panels for pedigree management of farmed white-leg shrimp (Penaeus vannamei) stocks validated in a VIE tagged family selection line

Establishing an effective and reliable system for tracking family pedigree is critical for the success of genetic improvement programs in aquaculture. Parentage assignment using molecular markers can provide an accurate and affordable pedigree management tool for selective breeding projects to maximize genetic gains while minimizing inbreeding levels. In this study, we evaluated 30 microsatellite loci for white-leg shrimp reported in earlier publications and selected 12 markers to develop two standardized multiplex microsatellite panels (SMpv01 and SMpv02) for pedigree management. Mean expected heterozygosity and polymorphic information content across the 12 loci included in the two panels were 0.725 and 0.704 respectively, indicating that the two multiplex panels would be highly informative for parentage assignment analysis. Simulation assignment runs of 10, 000 offspring, originating from 100 candidate dams resulted in complete maternity assignment with more than 11 loci at the 95% confidence level (CI). Capacity of the two marker panels for maternity assignment were tested using CERVUS and COLONY in a family selection line with full sibling relationships inferred from VIE tags. Among 369 individuals from 37 maternal families, CERVUS achieved 100% assignment while 69 assignments could not be matched with pedigree inferred from VIE tags. Overall assignment rate with COLONY was 94.3%, with 29 assignments not consistent with pedigree information from visible implant elastomer (VIE) tags. We also assessed the utility of VIE tags for a combination of nine tag colours and three tagging positions to track family ID via cross validation with molecular assignment. No statistical difference was found for random effects of tag position or VIE tag colour. This indicates that the VIE tag approach tested here would be a highly effective tool for pedigree management of cultured Penaeus vannamei stocks. In summary, our results provide two standardized multiplex microsatellite panels to support pedigree management of farmed white-leg shrimp in a selective breeding program.

Migration and Histologic Effects of Visible Implant Elastomer (VIE) and Passive Integrated Transponder (PIT) Tags in the Marine Toad (Rhinella marina).

Simple SummaryPassive integrated transponder (PIT) and visible implant elastomer (VIE) tags are commonly used to identify reptiles, amphibians, and fish. The aim of this study was to evaluate for pathologic changes associated with these tags in the marine toad (Rhinella marina). For the 56 toads in this study, all PIT tags were functional and 95% remained at the insertion site with little to no damage to the tissue. However, only 48% of VIE tags were functional, i.e., visible through the skin. Although there was little to no damage to the skin at the site of placement, the VIE was found to have migrated to the kidneys in 98% of toads as well as along the legs and sporadically in other internal organs. VIE in the kidney caused inflammation and damage to the vasculature that progressed in severity over time. Based on these findings, the authors recommend the use of PIT tags over VIE tags for identification of adult anurans, when feasible.Passive integrated transponder (PIT) and visible implant elastomer (VIE) tags are commonly used to identify reptiles, amphibians, and fish. Despite reports of good retention rates and little to no negative effect on survival time, migration remains a concern and histologic changes have not been widely evaluated. Fifty-six wild-caught marine toads (Rhinella marina) were marked with a PIT tag in the left caudal thigh and a VIE tag over the right gastrocnemius muscle prior to transport to the North Carolina Zoo. Fourteen toads were then humanely euthanized on day 9, 15, 32, and 62 for postmortem examination and histopathology which were compared to 10 control toads with no tags. All PIT tags were functional and 95% remained at the insertion site with minimal to no histologic changes. Externally, 48% of VIE tags were visible through the skin at the original site of injection under fluorescent or UV light. Upon gross examination of the tissues, VIE tags had an overall retention rate of 62% at the injection site, with similar retention rates across time points. Migrated VIE material was visible grossly and histologically in the kidneys of 98% of toads and along the right leg, proximally and distally, in 25% of toads. VIE material was also found sporadically in mesentery, colon, and free in the coelomic cavity. Histologically, VIE material in the skin was surrounded by minimal to mild granulomatous inflammation while in the kidney it was associated with dilation of the small vessels, edema, and granulomatous nephritis that progressed in severity over time. Based on these findings, the authors recommend the use of PIT tags over VIE tags for identification of adult anurans, when feasible.

Evaluation of Visual Implant Elastomer, PIT, and p‐Chip Tagging Methods in a Small‐Bodied Minnow Species

AbstractReliable fish tagging methods are needed to conduct studies (e.g., movement, habitat, abundance) that inform conservation and management decisions; however, dependable tagging approaches are lacking for many small‐bodied fishes. Therefore, our study objective was to determine survival, tag retention (visible implant elastomer [VIE], PIT, or light‐activated microtransponder [“p‐Chip”]) and tagging effects on short‐term growth of the federally threatened Arkansas River Shiner Notropis girardi. We also examined the use of anesthesia to reduce fish mortality (i.e., reduce handling time) and improve tagging efficiency. Fish tagged with p‐Chips had the highest survival (87%), whereas VIE‐tagged fish had the second highest survival (67%). Visible implant elastomer tags were retained in our fish 88% of the time, and retention was also high using p‐Chips (72%). Location of the VIE tag did not significantly affect survival or retention rates. Survival of PIT‐tagged fish significantly increased from 53% to 83% when handling time was reduced; however, tag retention was relatively low in both cases (50% and 45%, respectively). The majority of tagged fish across experiments (83–100%) gained weight regardless of tag type. If the research or management goal is to tag Arkansas River Shiner or similar species with individual identification, p‐Chips appear to be an appropriate tag. Particularly if cost is limiting or higher tag retention is needed, VIE tags would also be appropriate for batch tagging (i.e., no individual identification). Additional studies to broaden application of tagging to other small‐bodied species would be beneficial.

Identification of Individual Zebrafish (Danio rerio): A Refined Protocol for VIE Tagging Whilst Considering Animal Welfare and the Principles of the 3Rs.

Simple SummaryIn aquatic ecology research studies commonly employ a tagging technique named visible implant elastomer (VIE). Despite existing widespread guidance on the use of this marking technique on fish, there is still a lack of information regarding efficiency in small fishes, as well as its impact on fish welfare. The current paper highlights important animal welfare issues and introduces a newly improved VIE tagging protocol, presenting information on individual survival rate, tag retention, and use of different elastomer colours, quantified in different populations and age groups of zebrafish. Specifically, we compare a previously used tagging method with a newly improved protocol which places particular emphasis to the Three Rs, helping to refine this scientific procedure. The shared detailed protocol and information will be beneficial to the zebrafish research community and beyond.In aquatic ecology, studies have commonly employed a tagging technique known as visible implant elastomer (VIE). This method has not been widely adopted by the zebrafish research community and also lacks refinement with regard to animal welfare. The current paper introduces a new VIE tagging protocol, with the aim of improving existing tagging techniques by placing particular emphasis on the Three Rs. To improve animal welfare and fish survival, we added the use of an analgesic compound (lidocaine) through the marking procedure, followed by after-treatment with antiseptics (melaleuca, aloe vera, and PVP-I as active ingredients) to improve tissue regeneration and healing. The newly improved protocol has been quantitatively evaluated on different populations and age groups of zebrafish. This study will be useful to the scientific zebrafish community and to the wider field including biologist and aquarists, especially in consideration of animal welfare, where tagging techniques are considered as a potential noxious stimulus for fish.

Estimating population density of the medicinal leech Hirudo orientalis Utevsky and Trontelj, 2005 (Clitellata: Hirudinida) using Visible Implant Elastomer tags

ABSTRACT Medicinal leeches have lately come into the spotlight as useful and effective invertebrates in the treatment of some diseases and surgical procedures. Populations of the Iranian medicinal leech, Hirudo orientalis, are under considerable threat due to over-exploitation. To find a viable technique for estimating leech population size in their natural habitat, a tagging method using fluorescent dye was investigated. In the present study, to test the method’s efficiency, numbers of medicinal leeches were estimated in the artificial leech ponds of the University of Tehran, by the capture–mark–recapture method, using the Lincoln index. Leeches were caught from the ponds, marked using commercially available visible implant elastomer (VIE) tags, released and later recaptured. The technique proved successful, and low standard error values (7.07–11.85) in this study showed that the VIE tagging method could be applied as a useful tool for evaluating medicinal leech population size. This is the first use of this method to estimate medicinal leech population size.

Evaluation of Visible Implant Elastomer Tags in Wild Coastal Cutthroat Trout in the Marine Environment

AbstractWe evaluated the detectability of visible implant elastomer (VIE) tags in Coastal Cutthroat Trout Oncorynchus clarkii clarkii in the marine environment by comparing visually identified recaptures from VIE tags with known recaptures that were identified through genotype matching. A total of 89 individual Coastal Cutthroat Trout were marked in the lower jaw with colored VIE tags, sampled for genetics, and recaptured across 12 months in 2015. The rate of correspondence between the VIE tags and genetic matches was 92% (82/89) of the recaptured Coastal Cutthroat Trout in the nearshore marine environment. We found that red‐ and blue‐colored VIE tags were detected at a higher rate (100%) than were yellow‐ and orange‐colored tags (87.3% and 90.6%, respectively). In contrast, tag type (single or double), tag location (left or right), fish length (FL, mm), and time (days) since tagging had no effect on tag detectability during the study period. All of the tag colors were recovered for the maximum life of the study (up to 342 days). In all of the cases of nondetections (5/89), the tags were not identified upon initial recapture or subsequent capture events, suggesting that they were lost or not visible immediately upon insertion in the field—as opposed to being unidentified due to the degradation of tag detectability over time. The results of this study suggest that VIE tags have the potential to be detectable in juvenile and adult Coastal Cutthroat Trout for at least 12 months after insertion, with blue and red performing the best. Additional monitoring extending beyond 12 months after tagging would be necessary to identify the maximum life of VIE tags.

Visible implant elastomer (VIE) success in early larval stages of a tropical amphibian species.

Animals are often difficult to distinguish at an individual level, and being able to identify individuals can be crucial in ecological or behavioral studies. In response to this challenge, biologists have developed a range of marking (tattoos, brands, toe-clips) and tagging (banding, collars, PIT, VIA, VIE) methods to identify individuals and cohorts. Animals with complex life cycles are notoriously hard to mark because of the distortion or loss of the tag across metamorphosis. In amphibians, few studies have attempted larval tagging and none have been conducted on a tropical species. Here, we present the first successful account of VIE tagging in early larval stages (Gosner stage 25) of the dyeing poison frog (Dendrobates tinctorius) coupled with a novel anesthetic (2-PHE) application for tadpoles that does not require buffering. Mean weight of individuals at time of tagging was 0.12 g, which is the smallest and developmentally youngest anuran larvae tagged to date. We report 81% tag detection over the first month of development, as well as the persistence of tags across metamorphosis in this species. Cumulative tag retention vs tag observation differed by approximately 15% across larval development demonstrating that “lost” tags can be found later in development. Tagging had no effect on tadpole growth rate or survival. Successful application of VIE tags on D. tinctorius tadpoles introduces a new method that can be applied to better understand early life development and dispersal in various tropical species.

Factors Affecting the Retention of Visible Implant Elastomer (VIE) Tags in Smooth Newts (Lissotriton vulgaris) During the Breeding Period

Population parameters can be estimated on the basis of capture-mark-recapture (CMR) studies, which require accurate and continuous identification of studied individuals. Amphibians that cannot be identified by unique color patterns represent a problem for these types of studies due to variable interspecies suitability of different marking methods. One alternative to the traditional but questionable toe-clipping method is visible implant elastomer (VIE) tagging. VIE has been used successfully, mainly for tagging different species of terrestrial salamanders, but it has not been evaluated systematically for biphasic newts. In this study, the efficiency of VIE tagging was tested on smooth newts (Lissotriton vulgaris), with controls for body length, sex, position of tag, color of tag, and personal experience with tagging. Two tags, originally injected into each individual, were visible only in 39.5% of the newts after 49 days. Most of the tags that failed (72.4%) were lost completely. Retention rates for the VIE tags were lowest for younger tags but improved over time. Tags were lost more from the front than from the hind legs (42.1% vs. 34.2%), the person more experienced in marking had fewer tag losses (22.8% vs. 51.2%), and males lost more tags from their hind legs than females (52.8% vs. 17.5%). This study shows that VIE marking is not a conclusively reliable method for CMR studies of small salamanders during the breeding (water) period. The future of individual recognition, for the purpose of CMR studies, lies probably in non-invasive, computer-assisted photo identification methods.

The behavioural response of the white-clawed crayfish (Austropotamobius pallipes) to five standard marking techniques over a 14-day period

ABSTRACTThe white-clawed crayfish (Austropotamobius pallipes), is classified as endangered in the 2010 IUCN Red List and is protected under Irish and European legislation due to a drastic decline in abundance and range over the past century. Mark-recapture methods play a vital role in the process of estimating population size, and in the monitoring and conservation of mobile species. A variety of marking techniques are routinely used in a range of crayfish species for ecological research. The majority of information on the effects of these marking techniques on the physiology of crayfish species focuses on survivability and growth, whereas information is scarce on the effects on crayfish behaviour. This study investigates the behavioural changes of crayfish in reaction to five commonly used marking techniques in laboratory conditions. The marking techniques used were internal and external passive integrated transponder (PIT) tags, visible implant elastomer (VIE) tags, cauterisation and ablation. Effects of marking technique on behaviour were evaluated immediately after marking, and over a 14-day period, on 78 crayfish. Results indicated that the internal passive integrated transponder (PIT) tags negatively affected crayfish behaviour by increasing resting levels. Ablation and cauterisation also increased grooming levels, while marking reduced activity levels in general. These effects on behaviour occurred immediately after marking, but quickly dissipated. These results suggest that the use of internal PIT tags for marking white-clawed crayfish may need to be avoided as increased resting levels could lead to increased exposure out of refuge and predation. This may have a detrimental impact on the welfare and conservation of white-clawed crayfish and also lead to biased population estimates during mark-recapture projects. The remaining marking techniques (external PIT tag, VIE tag, ablation, cauterisation) may be used, as changes in behaviour will not have a detrimental impact and therefore should not lead to biased population estimates.

Effect of different stock types and dietary protein levels on key enzyme activities of glycolysis‐gluconeogenesis, the pentose phosphate pathway and amino acid metabolism inMacrobrachiumrosenbergii

A feeding trial was conducted to study the effect of dietary protein (DP) levels on the enzyme activities of different stocks of Macrobrachium rosenbergii juveniles, fed two diets prawn type diets either at optimum (ODP, 32%) or sub-optimum (SDP, 27%) dietary protein. The activity of key enzymes: glycolysis, gluconeogenesis, amino acid catabolism, pentose phosphate pathway, and energy metabolism was examined on different stocks of M. rosenbergii juveniles in various tissues (muscle, hepatopancreas, and gill). Wild juveniles of M. rosenbergii were collected from the west coast of India, Gujarat (G), Maharashtra (M) and from the east coast of India, Andhra Pradesh (A), and raised in culture ponds of 200 m2 at 1 juvenile m-2. The experiment was conducted for a period of 60 days. A Visible Implant Elastomer (VIE) Tag was injected into different prawn juveniles’ stocks A, (3.06–3.10 g), M, (0.80–1.01 g) and G (0.90–1.06 g) for the individual identification of each class. All the animals were acclimatized for 7 days before being released into the pond. Each of the two diets, the first with 27% SDP, termed the sub-optimum level (S), and the second 32% DP, termed the optimum level (O), was fed in triplicate ponds. The weight gain of stocked prawn was significantly higher for G stock (3.03 ± 0.18 g) compared to M stock (2.53 ± 0.25 g) and A stock (1.33 ± 0.10 g). In addition weight gain in ODP was significantly higher (3.05 ± 0.22 g) compared to SDP (2.11 ± 0.17 g). Furthermore, both protein level and stock type had a significant (p ≤ 0.05) effect on the survival rate, specific growth rate, and feed conversion ratio of the prawn. A significant interaction was recorded between metabolic enzyme activities and the variation of dietary protein levels and differences in M. rosenbergii stocks, in which stock “G” and “M” exhibited healthier enzyme physiological status than stock “A”. The findings presented here may conclude that the enzymes quickly respond to dietary protein manipulations of cultured shrimp. The results can be useful in identifying the optimum stock (genotypes) in a given culture condition and subsequently higher production may be achieved.

Long-term individual marking of small freshwater fish: the utility of Visual Implant Elastomer tags

Tracking wild animals over long periods of time is a non-trivial challenge. This has caused a bias in the availability of individual-based long-term datasets with the majority including birds and mammals. Visual Implant Elastomer (VIE) tags are now a widely used technique that may facilitate the collection of such data for fish and amphibians. However, VIE tags might have important drawbacks. Overall, four potential issues with VIE tags have been proposed: tag loss or misidentification, limited number of individual identifiers, enhanced mortality risk, and effects on intra-specific interactions. Here, we present three experiments in which we investigated these potential problems with VIE tagging in small freshwater fish both in the laboratory and in the wild, using the cooperatively breeding Lake Tanganyika cichlid Neolamprologus pulcher. We find VIE tags to be generally suitable for work with these fish as they did not impair survival, were recognisable up to 2 years after injection, and did not generally disturb group formation. Nevertheless, we identify specific issues of VIE tagging, including colour- and position-dependent variation in tag identification rates, and indications that specific colours may influence social behaviour. Our results demonstrate the suitability of VIE tags for long-term studies on small freshwater fish, while also highlighting the need of validating this method carefully for any species and study.Significance statementInformation on the survival, dispersal, and reproductive success of wild individuals across their lifespan is among the most valuable data in Behavioural Ecology. Because tracking of free-ranging individuals over extended periods of time is challenging, there exists a bias in the taxonomic distribution of such long-term datasets. Here, we investigate the suitability of visible implant elastomers (VIE) as a tracking technique to allow for the collection of such data also in small tropical freshwater fish. We show that VIE tags neither alter social behaviour in our study species, nor do they reduce survival, but they enable the tracking of wild individuals across years. We also identify colours and tag positions that are less suitable. We conclude that VIE tags can help produce long-term datasets also for small fish, provided certain precautions are met.

Influence of geographic origin on post-stocking survival and condition of European grayling (Thymallus thymallus) in a small river

The post-release survival and condition of 1+ year old European grayling Thymallus thymallus reared in a local (Husinec) and two 250–300 km distant, hatcheries (Pardubice and Hynčice) were evaluated by the recapture of tagged fish five months after release into the Blanice River, Czech Republic, the fish population of which was depleted by cormorant predation during several previous winters. The fish were marked using Visible Implant Elastomer tags and released into six sites along the river in May 2014: 100 locally sourced fish and 100 of a strain from a distant source per site. Significantly higher recapture of Husinec (33%) than Pardubice (20%) was found at one site but was offset by results in the remaining two sites into which they were stocked. Significantly higher site fidelity was shown by Husinec (12%) than Hynčice (7%) fish in the three sites. Lower initial weight and condition factor of the Husinec fish was equal to or higher than fish from the distant hatcheries at recapture. Some differences in final weight, length, and condition factor were found among groups regardless of release site. Lower recapture rate, growth, and condition were displayed in fish released into the three downstream sites (Husinec 1 and Hynčice). The results indicated the potential for successful use of non-autochthonous stock for grayling population recovery.

No Evidence of Site Fidelity in Atlantic Croakers or Spot in the Shore Zone of Lower Delaware Bay

AbstractWe conducted a mark–recapture study over a 98‐d period from June 20 through September 26, 2013, in lower Delaware Bay, USA, to examine movement and site fidelity of the Atlantic Croaker Micropogonias undulatus and Spot Leiostomus xanthurus. A secondary objective was to evaluate the effectiveness of visible implant elastomer (VIE) tagging for these species. Fish were tagged at five shore‐zone sites along approximately 5 km of gradually sloping sandy beach and at a site along 300 m of riprap‐hardened shoreline. Additional tagging occurred in an adjacent area (~36 ha) of nearshore habitat. Atlantic Croakers and Spot (15 individuals per species) were also tagged and held in the laboratory for 2 months to examine tag retention and fish survival. In total, 133 Atlantic Croakers and 253 Spot were tagged and released. The VIE tagging was shown to be a highly effective technique for studying the movement of these species; tag retention rates were 100% and 98% in Atlantic Croakers and Spot, respectively, and no mortality was observed among tagged fish held in the laboratory. No tagged fish were recaptured in shore‐zone or nearshore sampling, indicating a lack of site fidelity by either species in these habitats. These results demonstrate the need for more extensive research on the movements of shore‐zone nekton in the U.S. mid‐Atlantic region.

An evaluation of elastomer and coded wire tag performance in juvenile Tibet fish Oxygymnocypris stewartii (Lloyd, 1908) under laboratory conditions

A 95-day experiment was conducted to evaluate the performance of a visible implant elastomer tag (VIE) versus a coded wire tag (CWT) implanted in juvenile Tibet fish Oxygymnocypris stewartii (Lloyd, 1908; total length 5~7 cm) under laboratory conditions. Mortality, tag retention and growth in three groups of juvenile O. stewartii (VIE-tagged, CWT-tagged and control) in duplicate were determined in six indoor tanks (300-L/tank volume, 100 fish/tank) at 15.6 ± 0.5°C water temperature. Results showed that neither tagging method had a significant difference on the mortality of the experimental fish, but that the growth rate in the VIE group was significantly lower than in the CWT and control groups. Mean tag retention in the VIE group was 95.2%, and 98.9% in the CWT group, with no significant differences in tag retention in the two methods. The study indicates that both VIE and CWT are suitable short-term tagging methods for hatchery O. stewartii juveniles.