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To learn about the movement patterns of bigeye tuna in eastern Taiwan, pop-up satellite archival tags were attached on five tuna ~55 kg and prematurely detached and popped-up after 32 to 132 days-at-liberty. Two tags were physically recovered and provided fine-scale data archiving the full 47 and 132 days-at-liberty. The deepest descent recorded was 1,292 m and the coldest temperature visited 2.7°C. During daytime, the fish spent the majority of time above 400 m at temperatures from ~10 - 25°C and at nighttime; residency was largely confined to the mixed-layer from the surface to ~100 m. Vertical movements traversing through the thermocline during the daytime are based on physiological constraints and/or rapid directional changes conducive for optimal search strategies that increases the chances of prey encounters. Bigeye tuna appear to follow the diel vertical movements of prey organisms comprising the deep sound scattering layer to exploit them as a resource. [ABSTRACT FROM AUTHOR]

Freshwater mussels are one of the most endangered groups of animals. Translocation is a common conservation measure for protecting them, but the success of this procedure varies widely, and the reasons for failure are frequently unknown.The dispersal and mortality of freshwater mussels was studied using a novel method: the radio tracking of Unio crassus translocated to new sites during a reintroduction project for this threatened species in the River Biała (Poland).Individual mussels were equipped with radio transmitters (10 mussels at each of four sites during low water in autumn, and 10 mussels at each of 11 sites during the spring flood). After being released into the water, the mussels generally moved away from the bank, and then performed erratic movements, dispersing over a larger area on flat parts of the riverbed, finally congregating on steep parts of the river bed in shallow water (0.20 m) near the bank.Mussel mortality was surprisingly low: all survived the autumn trial, and 80% of the radio‐tracked adults survived the spring flood. Some of them were displaced quite far within the channel (>100 m), apparently suffering no harm. The confirmed cases of mortality were a few individuals that had become stranded on gravel bars formed during the flood that were now drying out.Long‐distance displacement was more frequent in lotic or regulated parts of the channel and in the parts where the channel morphology was unstable during the flood.Radiotelemetry should be used to test the suitability of receptor sites before translocation, in order to find places where mussels will choose to stay, and to standardize mussel detectability when monitoring relocation success. [ABSTRACT FROM AUTHOR]

The dynamic ebb and flood of tides makes the marine intertidal zone a habitat with temperatures that fluctuate rapidly in both space and time. This is problematic for slow intertidal organisms that cannot move at the speed of tidal fluctuations. The timing of low tides determines which days organisms may experience extreme body temperatures, controlling microclimate to a greater degree than weather patterns. When low tides occur midday, temperatures can exceed critical thermal maxima for many species. Although high shore areas experience the greatest environmental extremes, they often harbor untapped food resources. The periodicity of low tide timing creates a predictable cycle that marine animals can use to obtain food in risky areas while minimizing exposure to thermal extremes. Here, we use a two-part approach to assess whether the snail, Nucella ostrina , uses the predictability of the tidal cycle to obtain food in risky areas while minimizing exposure to thermal extremes. Radio tracking detected the presence/absence of snails in high shore feeding areas continuously for 14 weeks and physical thermal models approximated snail body temperature in those high shore areas. Snails were absent when extreme low tides occurred at times of high solar irradiance (midday). Comparing the subset of physical model body temperatures foraging snails experienced to all available body temperatures in the high shore environment showed snails in foraging areas disproportionately at 9–12 °C and absent at body temperatures > 31 °C, suggesting that N . ostrina is not present when and where thermal risk is greatest. These patterns demonstrate that censusing only at low tide yields an adequate picture of foraging behavior of this species in its natural habitat, and that migratory foraging behavior effectively moderates snail experience of environmental temperature in nature and may buffer this species from aerial warming. [ABSTRACT FROM AUTHOR]

The effect of nocturnal and diurnal releases on survival and migration of wild and hatchery-reared Atlantic salmon, Salmo salar, L., smolts ( n = 82) was investigated by releasing acoustically tagged smolts at the lower end of the River Vosso, Norway. Hatchery smolts was registered in the estuary within hours of their release, whereas wild smolts migrated over a prolonged period. The time of estuary exit was affected by river discharge but not by time of release. Progression rates were slow through the estuary (0.25 BL/s ± 0.18 SD) and fast through the fjord (1.80 BL/s ± 0.69 SD), and they were not affected by the time of release or origin. Survival to the fjord was low (0%-15%). Survival was not affected by body length but was lower for wild smolts than for hatchery smolts, and survival of the former was lower when the fish were released in daylight. [ABSTRACT FROM AUTHOR]

Downstream migration of radio-tagged Atlantic salmon smolts, Salmo salar L., was studied in the Kinzig, Germany, to examine effects of passing a run-of-river hydropower station with a movable bulb turbine. Immediate mortality for smolts passing the power station was low (3%-6%), probably facilitated by a curved rack in front of the turbine and the possibility to pass over it. Mortality in the impounded stretch above the power station was also low (1.5% extra mortality compared to a control stretch). The combined mortality due to hydropower was 5%-8%, excluding delayed effects. Most smolts followed the main flow passing through the turbine area (94%). Only few used a fishway (4%) or a nearby millstream (2%). Migration speed was slowed down at the power station, but the passage only caused a short delay (average/median 8.6/1.3 hr). However, even low mortality and short delays at several power stations and reservoirs may have considerable cumulative effects. [ABSTRACT FROM AUTHOR]

Electrofishing-based estimates of fish abundance are common. Most population models assume that samples are drawn from a closed population, but population closure is sometimes difficult to achieve. Consequently, we individually electrofished 103 radio-tagged trout of two species, westslope cutthroat troutOncorhynchus clarkii lewisiand brook troutSalvelinus fontinalis, in five streams in western Montana to quantify the influence of habitat and fish size on capture efficiency and movement related to electrofishing with unpulsed DC. First-pass capture efficiency was 46% and declined on subsequent passes. No variables were related to capture efficiency, and only the percentage of cobble or larger substrate was related to the probability that uncaptured fish would move during the first electrofishing pass. About 20% of the uncaptured fish did not move, and 95% traveled less than 18 m. We concluded that for these streams, the bias in abundance estimates from disregarding movement would be relatively minor. Received January 18, 2011; accepted June 11, 2012 [ABSTRACT FROM PUBLISHER]

We conducted an experiment to assess the effects of radio- tagging on adult spring Chinook salmonOncorhynchus tshawytschaduring the late stages of their spawning migration. Fish were captured at Roza Dam, Yakima River, Washington (river kilometer 208). Each fish had a radio tag inserted into the stomach via the esophagus and was then transported to a raceway and held for 50 d to assess survival. In the same raceway we also held a control group that was handled but not tagged and a group with externally attached transmitters. Survival of fish with gastrically implanted radio tags was low (10%), while 70% of controls and 90% of fish with externally mounted tags survived to the end of the experiment. Postmortem dissections revealed that after implantation, some radio tags had migrated from the stomach position to the posterior digestive tract and peritoneum. Fish from all treatments exhibited some level of tissue degeneration of the gastrointestinal tract. Gastric implantation should be used with caution, particularly for fish at vulnerable life stages. For spring Chinook salmon in the Columbia River basin, tagging with gastric implants should be conducted early in the freshwater migration to improve survival and reduce tag effects. Received September 30, 2011; accepted June 4, 2012 [ABSTRACT FROM PUBLISHER]

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This study investigated the movement patterns of yellow moray eels Gymnothorax prasinus using acoustic telemetry. Gymnothorax prasinus were found to use multiple sites within a localized area or home range. [ABSTRACT FROM AUTHOR]

Passive integrated transponder (PIT) tags have been widely used as a tool for various monitoring and research needs, but the retention of PIT tags has rarely been tested in resident salmonids. We quantified the short-term (≤1 week), annual (1 year), and long-term (≥1 year) retention rates of PIT tags placed in the peritoneal cavity of small resident rainbow trout Oncorhynchus mykiss in 11 study streams and assessed whether fish size and gender affected tag retention. Short-term retention rates were at least 92% and averaged 96% for all streams, but a paired t-test nevertheless indicated that experienced taggers had significantly higher short-term retention rates (mean, 98%) than did inexperienced taggers (mean, 95%). Annual retention rates for PIT tags averaged 81% among all study streams, ranging from a low of 67% to a high of 92%. Annual retention rates were lower for larger rainbow trout than for their smaller counterparts. Long-term tag loss for females was the same as for males for fish smaller than 15 cm but significantly higher for fish 15 cm or more, suggesting that egg expulsion was the primary cause of tag loss. [ABSTRACT FROM AUTHOR]

We evaluated the distribution and population characteristics of nonnative lake trout Salvelinus namaycush in Lake McDonald, Glacier National Park, Montana, to provide biological data in support of a potential suppression program. Using ultrasonic telemetry, we identified spatial and temporal distribution patterns by tracking 36 adult lake trout (1,137 relocations). Lake trout rarely occupied depths greater than 30 m and were commonly located in the upper hypolimnion directly below the metalimnion during thermal stratification. After breakdown of the metalimnion in the fall, lake trout primarily aggregated at two spawning sites. Lake trout population characteristics were similar to those of populations within the species' native range. However, lake trout in Lake McDonald exhibited lower total annual mortality (13.2%), later maturity (age 12 for males, age 15 for females), lower body condition, and slower growth than are typically observed in the southern extent of their range. These results will be useful in determining where to target suppression activities (e.g., gillnetting, trap-netting, or electrofishing) and in evaluating responses to suppression efforts. Similar evaluations of lake trout distribution patterns and population characteristics are recommended to increase the likelihood that suppression programs will succeed. [ABSTRACT FROM AUTHOR]

We evaluated the movement of adult brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss in relation to a catch-and-release area in the White River downstream from Beaver Dam, Arkansas. Nine fish of each species were implanted with radio transmitters and monitored from July 1996 to July 1997. The 1.5-km river length of a catch-and-release area (closed to angler harvest) was greater than the total linear range of 72% of the trout (13 of 18 fish), but it did not include two brown trout spawning riffles, suggesting that it effectively protects resident fish within the catch-and-release area except during spawning. The total detected linear range of movement varied from 172 to 3,559 m for brown trout and from 205 to 3,023 m for rainbow trout. The movements of both species appeared to be generally similar to that in unregulated river systems. The annual apparent survival of both trout species was less than 0.40, and exploitation was 44%. Management to protect fish on spawning riffles may be considered if management for wild brown trout becomes a priority. [ABSTRACT FROM AUTHOR]

Estimating salmon escapement is one of the fundamental steps in managing salmon populations. The area-under-the-curve (AUC) method is commonly used to convert periodic aerial survey counts into annual salmon escapement indices. The AUC requires obtaining accurate estimates of stream life (SL) for target species. Traditional methods for estimating SL (e.g., mark-recapture) are not feasible for many populations. Our objective in this study was to determine the average SL of chum salmon Oncorhynchus keta in the McNeil River, Alaska, through radiotelemetry. During the 2005 and 2006 runs, 155 chum salmon were fitted with mortality-indicating radio tags as they entered the McNeil River and tracked until they died. A combination of remote data loggers, aerial surveys, and foot surveys were used to determine the location of fish and provide an estimate of time of death. Higher predation resulted in tagged fish below McNeil Falls having a significantly shorter SL (12.6 d) than those above (21.9 d). The streamwide average SL (13.8 d) for chum salmon at the McNeil River was lower than the regionwide value (17.5 d) previously used to generate AUC indices of chum salmon escapement for the McNeil River. We conclude that radiotelemetry is an effective tool for estimating SL in rivers not well suited to other methods. [ABSTRACT FROM AUTHOR]

A streamside rearing facility (SRF) on the Big Manistee River, Michigan, was constructed for the purpose of rearing larval and age-0 lake sturgeon Acipenser fulvescens. Size, movement, and habitat selection were studied from 2007 to 2008 to determine whether there were differences between age-0 lake sturgeon reared in the streamside facility and natural cohorts. Lake sturgeon reared streamside showed no significant difference in length from their wild counterparts. Movement patterns were studied by attaching external radio transmitters to 17 age-0 streamside (198-250 mm total length) and 17 age-0 wild lake sturgeon (206-262 mm). The average weekly distances traveled by SRF fish ranged from 0.05-2.28 km (of 46 km surveyed) while wild fish traveled 0.04-2.81 km. In the river sections sampled, sand, pebble, and gravel comprised over 92.5% of the encountered substrates and Strauss index values indicated no differences in the presence of wild and SRF sturgeon over these substrates. Age-0 lake sturgeon were most often found in water 1.7 m deep with a velocity of 0.5 m/s, and no statistically significant differences were observed between wild and SRF sturgeon for either depth or velocity during the study years. By September, streamside-reared age-0 lake sturgeon attained a size similar to that of their wild cohorts and exhibited similar movement patterns and substrate association. [ABSTRACT FROM AUTHOR]

The movement of koi, a highly colored variant of common carp Cyprinus carpio, was monitored for 18 months in the Waikato River, New Zealand, with both radiotelemetry and acoustic telemetry. Koi had large total linear ranges (mean, 39 km), and most fish (74%) monitored for more than 250 d traveled between the Waikato River and lateral habitat. Differences in total linear range and mean daily movement between years suggest a behavioral response associated with reduced habitat availability during periods of low flow. The movements of koi were highly variable and infrequent, suggesting that important long-range movements are missed in short-term studies (<250 d), resulting in underestimations of total linear range. Our data suggest that large numbers of koi could have been intercepted traveling between lateral habitat and the Waikato River during 1 of 2 years, indicating that point source removal would be highly effective. [ABSTRACT FROM AUTHOR]

Genetic differences among muskellunge Esox masquinongy populations are related to residence in major river drainages, suggesting the existence of divergent stocks. By use of radio-telemetry we compared different seasonal and diel temperature selection in a southern Illinois reservoir for three geographically and genetically distinct stocks of age-2 muskellunge from throughout the latitudinal range of the species. Muskellunge from the Upper Mississippi River drainage were represented by the Leech Lake, Minnesota, population and the Ohio River drainage was represented by the Cave Run Lake, Kentucky, population. Progeny from North Spring Lake, Illinois, an interstock, or mixed-origin stock, were also evaluated. No differences in temperature selection were observed among stocks of juvenile muskellunge across seasons or diel periods. The seasonal mean temperatures of the water varied significantly—spring 21.7°C, summer 28.4°C, and fall 14.8°C, with an overall average temperature of 24.1°C, in agreement with previously published values obtained in laboratory trials. This lack of different temperature-selection patterns among stocks is in contrast with other life-history characteristics, for example growth, metabolism, and conversion efficiency, which have been shown to differ among populations and stocks. [ABSTRACT FROM AUTHOR]

The muskellunge was introduced in the Saint John River system from stockings in a headwater lake in the 1970s. They have migrated down the system as far as the river’s first dam, Mactaquac Hydroelectric Facility, at Fredericton and appear to have established several reproducing populations along the river. This exotic invader represents a potential threat to the severely depleted Atlantic salmon stocks in the river. We radio-tracked muskellunge over a 2-year period in the middle reaches. Home ranges extended to ∼100 km in both riverine and lacustrine areas, including 78% of individuals trans-located upstream of the dam making their way back through the dam successfully. Downstream of the dam, home ranges were <25 km. No spawning areas were detected. An isotope analyses of diet indicated that the large sub-adults and adults had established the greatest proportion of their biomass in a more 15N depleted environment typical of areas farther upstream. Isotope mixing models could not accurately determine the proportion of Atlantic salmon smolts that may have been consumed by muskellunge, but anadromous salmon had ≤7% probabilities of being in the diet. A bioenergetics model suggested ≤5% of the annual food intake by muskellunge occurs during the smolt out-migration period. For the Saint John River, the impacts of growing numbers of muskellunge are multi-faceted creating a complex management challenge. Muskellunge appear to minimally increase predation risk for Atlantic salmon smolts while their increasing numbers are creating a growing recreational fishery and potential threat to the native fish community and ecosystem. [ABSTRACT FROM AUTHOR]

A whole-lake acoustic telemetry array was utilized to monitor the three-dimensional position of 20 largemouth bass ( Micropterus salmoides). Code division multiple access (CDMA) technology enabled the simultaneous monitoring of the 20 transmitters (equipped with pressure and temperature sensors) at 15 s intervals with sub-meter accuracy. Fish were monitored between November 2003 and April 2004 to evaluate the behaviour of fish across different temporal and spatial scales. The distance moved by largemouth bass, assessed both on a daily and hourly basis, varied by season and was positively correlated with water temperature. For example, daily movement rates were 2.69 ± 1.45 km/day in mid November (average daily water temperature 5.9°C), 2.24 ± 0.73 km/day in early January (5.1°C), and 7.28 ± 2.62 km/day in mid April (7.7°C). Interestingly, daily movement rates varied by as much as 25 fold among individual fish. Visualization of fish swimming paths revealed that whereas some fish occupied discrete areas and made only localized movements, other individuals made lengthier journeys covering much of the lake in periods of as little as one day. Analysis of fish behaviour at a finer temporal scale revealed that during the winter, fish spend more than 95% of their time swimming at speeds less than 0.1 m/s (0.07 ± 0.24 m/s). During late fall, and especially in spring, swimming speeds were higher with mean swimming speeds of 0.11 ± 0.27 m/s and 0.19 ± 0.29 m/s, respectively. When the telemetry dataset was queried to simulate 24 h manual tracking intervals, it was clear that manual tracking data would not have been representative of actual daily movement rates, underestimating daily movement and swimming speeds by at least 75 fold. This study identifies the importance of evaluating fish activity at multiple spatial (whole lake to sub-meter position) and temporal (seasonal to seconds) scales and illustrates the potential of CDMA telemetry to yield such data. [ABSTRACT FROM AUTHOR]

Degradation and destruction of valuable spawning and rearing habitat due to anthropogenic changes (e.g., flow modification and channelisation) is known to have dramatic impacts on fish populations. To compensate for habitat losses due to hydropower development, an artificial fluvial habitat channel (‘Compensation Creek’) was constructed in south-central Newfoundland, Canada. The creek was designed to include appropriate habitat features for the two dominant salmonid fish species, landlocked Atlantic salmon ( Salmo salar L.) and brook charr ( Salvenius fontinalis Mitchell). The study examines the habitat use of landlocked Atlantic salmon and brook charr in the Compensation Creek using electromyogram (EMG) radio telemetry. Ten landlocked Atlantic salmon and eight brook charr were captured and tagged with EMG transmitters. In laboratory swimming experiments, the EMG values were calibrated against swimming speed. Fish were then released in the Compensation Creek and tracked on a daily basis. The results show that (1) during residence in the creek, both species used preferentially the habitat features designed to match their rearing habitat preferences, and (2) swimming speed did not vary among habitat types for either species. [ABSTRACT FROM AUTHOR]

Ecological and economical sustainability of marine aquaculture operations depend on proper feeding management. Feed wastage from overfeeding is a source of pollution, represents futile use of precious marine resources, and undermines the economic viability of operations. Additionally, underfeeding reduces growth and fish welfare. Finding an optimal feeding regime in terms of temporal and spatial distribution of the feed ration require intimate knowledge of the individual feeding behaviour of fish sustaining intensive culturing conditions. Fish telemetry has proved to be a valuable tool for studying spatial behaviour in sea cages, however there are currently no practical methods available with respect to detection of actual feed intake in fish on the individual level. The present study investigates pressure transients arising in the opercular cavity of farmed Atlantic salmon ( Salmo salar L.) in connection with feeding, and whether such measurements can serve as an indication of feed ingestion. A technical solution to the sensing problem based on a differential pressure transducer is presented along with typical pressure signal traces obtained during feeding in a hard wire tank experiment. Measurements showed considerable variation of sub-ambient pressure transients (1.5 kPa ± 0.95) and their duration (519 ms ± 117), suggesting that the fish modulates its strike intensity depending on the particular feeding situation. Despite variations in scale, opercular pressure waveforms have distinct structural features that repeat between feeding instants. From a signal processing point of view waveforms provide sufficient information with respect to isolation and detection of feeding incidents, which is important with respect to a potential implementation of the sensing principle in a telemetry tag design. Issues regarding development and application of a telemetry system based on this sensing principle are discussed. [ABSTRACT FROM AUTHOR]

A telemetry study in a Norwegian regulated river was conducted through a 12-day period in mid-winter 2003. The objective was to study activity (defined as number of movement per hour) and movement (defined as distance moved per hour) during different ice formation events. Twenty-four Atlantic salmon ( Salmo salar L.) parr were radio tagged and continuously monitored by both manually tracking ( N = 24) and by fixed recording stations ( N = 15). Detailed data on climate, flow and ice formation and its spatial distribution were collected and used in the analyses. Fish activity was not found to be affected by their size ( L F). There was a significant difference in activity between diel periods with highest activity during dusk (5–6 p.m.). Between high and low flow (mean ± SD, 21.1 m3 s−1 ± 1.7 SD and 11.1 m3 s−1 ± 1.7 SD, respectively) no significant difference in activity was found. During the experiment extensive anchor ice growth occurred mainly in the riffle part with thickness up to 50 cm. Juveniles tend to avoid riffle section during anchor ice formation and exploited ice covered areas, indicating critical and preferable habitats respectively. Further, a significant difference in movement was found between five selected ice events with highest mean movement during an anchor ice event and lowest mean movement during an ice break up with no anchor ice formation. No significant difference in activity or movement between parr exposed to frazil ice and parr not exposed were found. [ABSTRACT FROM AUTHOR]

Adult roach Rutilus rutilus (L.) ( N = 24; 19.9–36.1 cm FL) from three highly fragmented Belgian rivers were tagged with surgically implanted radio transmitters. Their seasonal movements were observed from March to August 2004 (circum reproduction period) in river stretches delimited by two physical barriers. In the three rivers, roach displayed similar patterns of movements which were mainly influenced by the date of observation (movements increased in late April–May) and water temperature (travel distances were more important when water temperature ranged between 10°C and 14°C). Roach sometimes cleared physical obstacles. The mean distances travelled in each river were relatively short (max. 2.5 km) and mainly influenced by the length of the study reach, which was delimited by physical barriers. [ABSTRACT FROM AUTHOR]

Radio-tagging is widely used for studies of movements, resource use and demography of land vertebrates, with potential to combine such data for predictive modelling of populations from individuals. Such modelling requires standard measures of individual space use, for combination with data on resources, survival, dispersal and breeding. This paper describes how protocols for efficient collection of space-use data can be developed during a pilot study, and reviews the ways in which such data can be used for space-use indices that help answer biological questions, with examples from a study of riverine pike ( Esox lucius). Analyses of diurnal activity and spatio-temporal correlation were used to assess when to record locations, and analyses of home range increments were used to define the number of location records necessary to assess seasonal ranges. We stress the importance of developing protocols that use minimal numbers of locations from each individual, so that analyses can be based on samples of many individuals. The efficacy of link-distance (e.g. cluster analysis) and location density (e.g. contouring) techniques for spatial analysis for river fish were compared, and the utility of clipping off areas to river banks was assessed. In addition, a new automated analysis was used to estimate distances along river mid-lines. These techniques made it possible to quantify interactions between individuals and their habitat: including a significant increase in core range size during floods, significant preference for deep pools, and a lack of exclusive territories. [ABSTRACT FROM AUTHOR]

Evidence‐based management of fisheries means being continually open to new sources of scientific findings and data, but this is difficult when there is uncertainty or disagreement about their value and utility. We submit that this is the case for rapidly advancing animal tracking research, or biotelemetry. While biotelemetry science has been broadly accepted in fisheries and aquatic research communities, its incorporation into fisheries policy and management has been limited. To gain insight into this disjuncture, we conducted an exploratory study of perspectives on biotelemetry among government employees and nongovernmental stakeholders involved in co‐managing salmon fisheries in Canada's Fraser River. Using a knowledge mobilization theoretical framework, we examine how respondents perceived biotelemetry research across three dimensions: its epistemic value (its capacity to generate useful and valid new knowledge), its practical value (relative to real‐world considerations such as cost), and its degree of fit or discord with existing policy and management practices. We find a wide range of views between both groups, which may explain the hesitant uptake of biotelemetry into policy and management in this case. We conclude by advancing several research questions as a guide for future study of the integration of new sources of knowledge into evidence‐based management. [ABSTRACT FROM AUTHOR]

The article discusses research in New Jersey involving studying and tagging Black Sea Bass in order to investigate their sex change. It states that if a male Black Sea Bass is removed from a group of females the largest female will change her sex. It also suggests that the sex change patterns in their populations can be related to overfishing.