Physiological responses of Pacific halibut, <Emphasis Type="Italic">Hippoglossus stenolepis</Emphasis>, to intracoelomic implantation of electronic archival tags,with a review of tag implantation techniques employed in flatfishes

Management of Pacific halibut (Hippoglossus stenolepis), a long-lived flatfish, is complicated by possible ontogenic and sex-specific variation in migration. Archival tags promise the ability to help uncover long-term movement patterns at the individual level, if the tags can be retained and recovered from healthy fish. We examined fifteen individuals (69–90 cm fork length) for long-term physiological response to intracoelomic implantation of three types of archival tags: fully internal, internal with right angle protruding light stalk, and internal with straight protruding light stalk. Tags represented 0.05–0.16% of initial fish weights. Fish were reared at 10.8 ± 1.1°C for 59 weeks post-surgery. One fish died after 39 weeks from thermal stress unrelated to the surgical procedure. Temporal variation in behavior of tagged fish was indistinguishable from that of controls (n = 15 tagged, 5 controls). Treatment and control-group fish grew at similar rates. No tag expulsion or physiological response was evident in the individual that died at 39 weeks, but nine of eleven individuals dissected at the end of 59 weeks had developed internal responses. These responses ranged from deposition of fibrous protein and/or calcitic material on tag surfaces to partial or full tag encapsulation in either the visceral peritoneal layer (fully-internal tags) or the intestinal mesenteries (stalk-bearing tags). The responses were within the range reported for other pleuronectids implanted with tags of similar configuration and may have implications for design and interpretation of long-term tagging studies. Encapsulation may reduce the probability of tag recoveries even in the absence of tag expulsion, especially in species eviscerated at sea.     

External tagging does not affect the feeding behavior of a coral reef fish, <Emphasis Type="Italic">Chaetodon vagabundus</Emphasis> (Pisces: Chaetodontidae)

Increasingly, the ability to recognize individual fishes is important for studies of population dynamics, ecology, and behavior. Although a variety of methods exist, external tags remain one of the most widely applied because they are both effective and cost efficient. However, a key assumption is that neither the tagging procedure nor the presence of a tag negatively affects the individual. While this has been demonstrated for relatively coarse metrics such as growth and survival, few studies have examined the impact of tags and tagging on more subtle aspects of behavior. We tagged adult vagabond butterflyfish (Chaetodon vagabundus) occupying a 30-ha insular reef in Kimbe Bay, Papua New Guinea, using a commonly-utilized t-bar anchor tag. We quantified and compared feeding behavior (bite rate), which is sensitive to stress, of tagged and untagged individuals over four separate sampling periods spanning 4 months post-tagging. Bite rates did not differ between tagged and untagged individuals at each sampling period and, combined with additional anecdotal observations of normal pairing behavior and successful reproduction, suggest that tagging did not adversely affect individuals.     

Tag retention,wound healing,and subsequent reproductive history of southern right whales following satellite‐tagging

This paper presents data from 48 resightings of 16 southern right whales that were satellite‐tagged on the South African coast in September 2001, up to and including 2012. Tag performance in terms of number of days with locations received was significantly higher in males than females, and lowest in cows with calves, and attributed to behavioral differences leading to variable degrees of antenna damage. Resightings occurred from 4 to 4,054 d after tagging: tags were retained in all whales seen within 27 mo, but were apparently shed in all but one individual seen within 36 mo of tagging. The exception was a whale that still had the tag present 11 yr after tagging. Healing at the tag site occurred gradually and within 5 yr of tagging (and 2 yr after tag shedding). No significant difference in the subsequent frequency of calving was detected between 12 tagged and 382 untagged females photographed contemporaneously, and although statistical power was low, a 21% or greater reduction in calving rate in tagged females would seem incompatible with the observations. The death of one female 3 yr after tagging was more likely attributable to a ship strike on an animal debilitated by a prolapsed uterus.     

Movements and Site Fidelity of two Juvenile Fish Species Using Surf Zone Nursery Habitats Along The Southeastern North Carolina Coast

We examined the extent of movements of juvenile Florida pompano, Trachinotus carolinus, and gulf kingfish, Menticirrhus littoralis, along an open ocean beach. Fishes were collected by seine at three sites along Masonboro Island and Carolina Beach, NC between 7 June and 7 July 1995. All specimens 40 mm standard length (SL) were tagged with coded wire tags and released at the capture sites. Between 7 July and 9 August and on 15–16 September Masonboro Island and northern Carolina Beach were surveyed for tagged fish. A controlled tag mortality/retention study was conducted for both species. Overall, 1569 Florida pompano (40–135 mm SL) were tagged. Sixty-one (3.9%) of these were recaptured, and only eight moved away from the original tagging sites. The largest movements by two Florida pompano were 2.1 and 10.5 km. Many fish remained at their original tagging sites for 21–27 days. Of 488 gulf kingfish (36–158 mm SL) tagged, 16 (3.3%) were recaptured. Gulf kingfish also exhibited little movement away from tagging sites during the study, with individuals remaining at original tagging sites up to 21 days. Stock size estimates for Florida pompano ranged from 3354 to 4670 among the tagging sites, with densities ranging from 1.9 to 2.6 fish m^–2. The remarkable site fidelity exhibited by these two species suggests that resources were not limiting or that predation pressure was not high enough to cause large scale movements during the study. This implies that local disturbances could impact behavior or survival of juvenile fishes in the surf zone.     

Subcutaneous injection of visible implant elastomer in sterlet (Acipenser ruthenus Linnaeus, 1758): a study on compatibility and retention

The purpose of this study was to mark endangered sterlet (Acipenser ruthenus) with visible implant elastomer (VIE) in order to assess mortality, compatibility, retention, persistence and histological reactions resulting from this tagging technique. It was hypothesized there would be only minor effects on the fishes' health, and assumed that acute effects would be more pronounced than long‐term effects. On 11 September 2013, 20 specimens were tagged ventrally with visible implant elastomer, 20 received a subcutaneous injection with 0.9% NaCl solution, and another 20 served as untreated control. Mean total length was 28.0 ± 1.8 cm and mean body mass 64.1 ± 12.0 g. The sterlets were kept in four 4,000‐L tanks filled with 2,400‐L water. Acute effects were monitored for 95 days, where fish were held at temperatures between 2.4°C and 15.2°C, reflecting outdoor conditions. Chronic effects were examined 282 days post‐tagging through histological sections of the tagging region in five sterlets. During the first 95 days of observation, tag retention was 100%. No signs of incompatibility were detected. Body mass did not significantly differ between VIE‐tagged fish and controls. At day 282 post‐tagging, however, distinct tissue reactions were visible at the tagging sites of nine fish. Histological examination of five fish revealed a variable degree of infiltration with leukocytes in the areas around the elastomer, which did not necessarily correspond with the externally visible degree of inflammation. After medical treatment, the lesions healed without complications, whereas the retention rate of the VIE tags was 5%. According to the findings, the tag location rather than the tag itself was responsible for the externally visible irritations, indicating that the ventral subcutis of sterlet is not a suitable site, even for small VIE tags in long‐term studies. The results of this study also suggest that VIE marking should in general be critically evaluated before application in field studies.     

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.     

Effects of double bands on Magellanic Penguins

ABSTRACT Banding penguins is controversial because bands can alter the survival, reproduction, and behavior of marked individuals. The effects of bands are not consistent among band types and, although stainless steel is thought to be better than other materials, tests of the long‐term impact of bands on tag‐loss rates and the reproduction and survival of individuals are needed. We tested three types of external tags on Magellanic Penguins (Spheniscus magellanicus) to measure band effects and tag‐loss rates. In 1993, we double‐tagged 300 penguins with aluminum flipper bands, stainless‐steel flipper bands, or small (2 mm × 10 mm) metal tags attached to foot webbing. We searched for double‐tagged birds for 13 of 15 yrs (1994–2008). Aluminum bands deformed, caused feather wear, injured and killed some penguins, and were lost more often than stainless‐steel bands or web tags. During the first 2 yrs of our study, at least nine penguins lost one aluminum band (N= 71 penguins resighted), but no penguins lost a stainless‐steel band (N= 84) or a web tag (N= 88). During the next 13 yrs, five penguins lost one of their two web tags (N= 89), but none lost a stainless‐steel band (N= 84). Females laid eggs of similar size before they carried a band and in the year following tagging (P= 0.09). The type of tags a female carried did not significantly change egg size (P > 0.22). During the first breeding season after tagging, penguins with aluminum bands had lower reproductive success than penguins with stainless‐steel bands or web‐tags (P= 0.04). The annual survival of females with two stainless‐steel bands was lower (0.79) than that of males with two stainless‐steel bands or males and females with two web‐tags (0.87). Aluminum bands injured Magellanic Penguins, were lost at high rates, and should not be used. Double stainless‐steel bands had no apparent effects on adult male Magellanic Penguins, but reduced survival rates of adult females. A single stainless‐steel band would likely have less impact than two bands, and our results suggest that the impact of a single band would be difficult to measure.     

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.     

Tag retention and mortality of adult Atlantic salmon Salmo salar gastrically tagged with different sized telemetry transmitters

A batch of 1 sea winter pre‐spawning adult Salmo salar from the Bush river in Northern Ireland, U.K., were gastrically tagged with large (13 mm diameter) and small (9 mm diameter) dummy acoustic telemetry tags alongside untagged control fish. Survival differed between control and tagged fish and the estimated probability of survival by the end of the study for control fish with no tag was 0·94, small tags was 0·90 and large tags was 0·72. Tag loss through regurgitation was slightly higher for fish tagged with larger tags than for fish tagged with smaller tags and the estimated probability of tag loss for fish with a small tag was 0·10 and for large tags was 0·14.     

Evaluation of passive integrated transponder tag retention from two tagging locations in juvenile pallid sturgeon

Population augmentation and propagation of pallid sturgeon (Scaphirhynchus albus) have been a focus of scientists since the mid‐1990s. Various tag types have been used to gain a better understanding of population characteristics, stocking success, and movement patterns. Passive integrated transponder (PIT) tags have been consistently used since the inception of recovery efforts to mark age‐1 and older pallid sturgeon. This tag has been successfully used with other sturgeon species, and tagging protocols for pallid sturgeon were developed in response to those successes. Tag retention rates in pallid sturgeon have been reported as variable or unknown and there has been no formal study to determine PIT tag retention in pallid sturgeon, particularly with age‐1 individuals that are propagated in hatcheries to be stocked into the wild. The objective was to evaluate retention rates of PIT tags inserted into the operculum and along the base of the dorsal fin of age‐1 pallid sturgeon (total fork length [FL] range = 214–358 mm). Tagged sturgeon (n = 80) were held in a large holding tank and inspected for tag loss twice a month for a total of 189 days. Final tag retention was 83% for tags inserted into the operculum and 85% for tags inserted near the dorsal fin. Tags shed from the operculum were from smaller fish (mean FL = 265 mm) and losses occurred during the first 60 days of the experiment. Tags shed from the dorsal site were predominantly from larger individuals (mean FL = 305 mm) and losses were continual throughout the experiment. Future research should determine size‐specific tag retention rates so that hatcheries can maximize retention in either tag placement location.     

Telemetry tag effects on juvenile lingcod Ophiodon elongatus movement: a laboratory and field study

This study tested the behavioural effects of tagging subyearling and yearling lingcod Ophiodon elongatus with acoustic telemetry tags in laboratory tanks and in the natural environment (Puget Sound, WA). In the laboratory, tagged individuals showed less movement and feeding behaviour soon after tagging than untagged controls. The effect dissipated after c. 1 week, presumably as the tagged O. elongatus recovered from surgery or adjusted to the presence of the tags. This dissipation enabled a field study that compared early‐tagged individuals with a long recovery period after tagging to recently‐tagged individuals with a short recovery period after tagging. Consistent with findings from the laboratory experiment, recently tagged individuals showed less movement away from three release sites in Puget Sound than early‐tagged individuals. Together, the laboratory and field results provide evidence of temporary tag effects on actual movement in the natural environment and provide a method for testing tag effects in the field. This study suggests that subyearling and yearling O. elongatus should be held for a recovery period before release. If holding after tagging is not an option, then movement data collected during the first week should be interpreted cautiously.     

Efficacy of tagging European catfish Silurus glanis (L., 1758) released into ponds

The efficacy and sub‐lethal consequences of single and double tagging European catfish Silurus glanis with Petersen disc and passive integrated transponder (PIT) tags were examined in short (laboratory) and longer‐term (field) experiments. Tag retention in the laboratory was 100%, with normal behaviour (i.e. feeding) in all fish returning within 36 h. In the field, 65 of 120 tagged S. glanis were recaptured from five small study ponds, with 85% retaining their PIT tags, though recapture rates and tagging efficacy were highly variable amongst locations. This is consistent with literature for other fishes, suggesting that tagging efficiency is variable across species and largely context dependent (fish length, tagging location, habitat).     

Effect of GPS tagging on behaviour and marine distribution of breeding Arctic Terns Sterna paradisaea

Tracking tags have been used to map the distributions of a wide variety of avian species, but few studies have examined whether the use of these devices has impacts on the study animals that may bias the spatial data obtained. As Global Positioning System (GPS) tags small enough for deployment on terns (family: Laridae) have only recently become available, until now tracking of this group has been conducted by following unmanipulated individuals by boat, which offers a means of comparing distributions obtained from GPS‐tracking. We compared the utilization distributions (UDs) of breeding Arctic Terns Sterna paradisaea obtained by GPS‐tracking 10 individuals over 2 weeks, with UDs derived from contemporaneous visual boat tracks from 81 individuals. The 50% and 95% UDs of both methods had high similarity scores, indicating good agreement in the density distributions derived from the two methods. The footprints of the UDs of tagged birds were ~ 75–80% larger, which may reflect an effect of tagging on foraging range or the occasional inability to follow by boat individuals which roamed further from the colony. We also compared the nest attendance and chick provisioning rates of adults that were (1) fitted with a GPS tag and leg‐flag, (2) handled and marked with a leg‐flag but not tagged and (3) fitted with a leg‐flag in a previous year but unhandled in the year of the study. There was some evidence that birds fitted with both a GPS tag and leg‐flag spent slightly less time at the nest compared with unhandled birds and those fitted with a leg‐flag only. Both treatments where birds were fitted with a leg‐flag in the year of the study had similarly lower provisioning rates to those of unhandled control birds > 48 h after handling, suggesting that negative effects on provisioning are due to capture and handling or leg‐flag attachment rather than to GPS tag attachment/loading per se. Overall brood‐provisioning rate was compensated for by the increased effort by the unhandled partner. Our study suggests that despite slight effects of GPS‐tagging on behaviour, the estimates of marine density distribution obtained were very similar to those of unmanipulated birds.     

Long‐term effects of passive integrated transponder tagging (PIT tags) on the growth of the yellow European eel (Anguilla anguilla (Linnaeus, 1758))

Passive Integrated Transponder tags (PIT tags) are recommended as the most suitable method for tagging fish on the basis of their high retention and fish survival rates. The objective of this study was to determine the long‐term effects (between 1 and 11 years) of the PIT tag on the growth of the yellow European eel (Anguilla anguilla). A difference of more than 50% was observed in the growth of marked and unmarked yellow eels. If this is a general long‐term effect in all eels, it would seriously restrict the use of PIT tags for studying the dynamics of European eel populations, and so for their management.     

A passive integrated transponder tag implanted by a new alternative surgical method: effects on the oriental weather loach (Misgurnus anguillicaudatus) and application in a small irrigation system

We validated the effects of a passive integrated transponder (PIT) tagging process on the oriental weather loach Misgurnus anguillicaudatus. Laboratory experiments were conducted to assess the effects of PIT tagging on fish survival, growth, wound healing, and tag omission. Two tagging protocols, standard syringe injection versus insertion through a small hole pierced by a fine needle-shaped awl, were compared using a 12.5 × 2.07 mm² tag. A control group was also included. In comparison with the awl technique, syringe injection heightened the mortality of the loach and delayed healing of the wound caused by tag insertion. No effects of either PIT tagging method were detected on the growth of surviving loach. We also field-tested similarly tagged populations within a river-based irrigation system of Sado Island, Japan. Two different sized tags (long, 12.5 × 2.07 mm²; short, 8.5 × 2.12 mm²) were compared by using antenna loggers which detected fish movement through gates and automatically logged tagged fish’s tag IDs and timestamps. By comparing logged data and actual fish collection surveys both below and above the gates, 77% and 30% of actual loach movements were confirmed to have been successfully logged for the long and short tags, respectively. The awl insertion technique with the longer tag is therefore recommended for use in similar studies of smaller fish species.     

Retention of loop,monel, and passive integrated transponder tags by wild,free‐ranging Lake Sturgeon (Acipenser fulvescens Rafinesque, 1817)

Tagging or marking of fish is instrumental to fisheries biologists and managers seeking to distinguish groups of fish, track movement or migration patterns, and monitor population characteristics. However, tag loss can inhibit the ability of biologists and managers to reach these objectives. The ability of Lake Sturgeon to live for long periods of time and reach large sizes, in combination with their dynamic spawning activity, requires tags to be retained under a variety of environmental and physically demanding conditions. This study evaluated tag retention of loop, monel, and passive integrated transponder (PIT) tags on wild, free‐ranging Lake Sturgeon in Lake Huron and the St. Clair – Detroit River System. Lake Sturgeon in this study were double‐tagged with both a PIT tag under one of the three anterior‐most dorsal scutes and an external tag (loop or monel) at the base of the dorsal fin. Fish were at large for up to 16 years. Overall, tag loss for PIT tags was 1% followed by monel tags at 12% and loop tags at 36%. Tag loss for loop tags was higher when the initial length of Lake Sturgeon tagged was smaller. Tag loss for monel tags increased with time at large but was not related to length at initial tagging. Monel tags left behind abrasion marks when attached to smaller Lake Sturgeon. PIT tag retention was higher than reported in previous studies that tagged other sturgeon species in different body locations. Monel tag retention was higher than other external tag types evaluated in previous studies while loop tags had similar retention rates to external tag types. Most previous studies on tag retention of sturgeon species were of shorter duration and conducted in laboratory settings, therefore loop tags may have performed more favorably during studies under short term laboratory settings. Results of this study suggest that PIT tags inserted below dorsal scutes represent a viable option for long‐term tracking of Lake Sturgeon. Monel tags attached at the base of the dorsal fin also seem to be a viable option relative to other external tag types, but should be limited to larger sturgeon as they can leave behind abrasion marks.     

Mark retention and fish survival associated with a low-cost marking technique for common carp Cyprinus carpio (Linnaeus, 1758)

Common carp (Cyprinus carpio, [Linnaeus, 1758]) have long been established in the United States and in some cases their populations can be very dense, leading biologists to expend significant effort towards reducing numbers of common carp in some populations. Estimating abundance of common carp prior to removal efforts would be useful in evaluating success of these removal efforts, but marking large numbers of fish can be expensive. Therefore, a low-cost tagging option is needed. In this study, we used tank and field experiments to determine the retention and longevity of hole-punch marks in the opercula of common carp. For the tank experiment, fish were double marked with a size-3 self-piercing tag and an operculum hole-punch mark (using a paper hole-punch tool with a hole diameter of 6.4 mm) on opposite sides of the fish. Over the entirety of the 180–day tank experiment, retention of the self-piercing tags and hole-punch marks was 100% and no marking mortality was observed. For the field experiment, 883 common carp were tagged at random in two groups, a double-marked group (n = 416, both self-piercing tags and hole-punch) and a single-mark group (n = 467, self-piercing tag). Fish were sampled monthly for 398 days. Because the length distribution sampled was bimodal, we evaluated tag retention of fish <330 mm TL (small fish, n = 273) and > 331 mm TL (large fish, n = 143), separately. Hole-punch mark retention was high for both size classes throughout most of the field experiment. For large fish, retention of hole-punch marks was 100% for the entire 398-day experiment. For small fish, retention of hole-punch marks was 100% through 184-day and remained above 93% through 328-days, but declined to 0% by day 398. Our results suggest that the operculum hole-punch mark is a valuable low-cost, long-term technique for tagging common carp.     

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.     

Patterns of migration and residency in coastal cutthroat trout Oncorhynchus clarkii clarkii from two tributaries of the lower Columbia River

Coastal cutthroat trout Onchorhynchus clarkii clarkii life-history variants, migration and freshwater residency were monitored using stationary passive integrated transponder (PIT) tag arrays in two tributaries of the Columbia River from 2001 to 2005 (Abernathy Creek, river kilometre, rkm 76) and from 2002 to 2005 (Chinook River, rkm 6). In 2001–2003 and 2002–2003 (Abernathy and Chinook, respectively), 300–500 coastal O. c. clarkii were captured in each tributary by electrofishing and implanted with 23 mm PIT tags. PIT arrays monitored movements from the initiation of tagging through the spring of 2005. Rotary screw traps were also operated on both tributaries. In Abernathy Creek, 28% of tagged individuals were observed through either active capture or passive interrogation. Of these, 32% were identified as migrants and 68% were identified as residents. In the Chinook River, 48% of tagged fish were observed subsequent to tagging; 92% of these fish were migrants and only 8% were resident. In both tributaries, a greater proportion of resident fish were in the upper reaches. The majority of migrants (78–93%) moved the spring following tagging. Migrants leaving at age 2+ years tended to grow faster than those that migrated at age 3+ years or residents. Patterns of growth or growth opportunities may influence both patterns of life-history expression and the timing of migration.     

A Comparison of Floy and Soft VIalpha tags on Hatchery Arctic Charr, with Emphasis on Tag Retention, Growth and Survival

The Floy FTF-69 'fingerling' tag and the soft VIalpha tag are designed to be used on small salmonid fishes (> 100 and > 150mm, respectively). The two tags were compared for 160 days on hatchery-reared Arctic charr, Salvelinus alpinus, (170–209mm). Tag retention and effects on growth rate and survival were analysed. VIalpha-tagged and untagged control fish had similar growth rates and grew significantly faster than Floy-tagged fish during the experiment. Tag retention was significantly higher for Floy tags (94%) than for VIalpha tags (78%). Most VIalpha tag loss (11%) took place within the first 10 days of tagging while there were no Floy tags lost during this period. Survival rates were about equal for all three groups (96–98%), and thus the tags did not seem to affect the survival of charr under hatchery conditions.