Early approaches to surgical implantation of electronic tags in fish were often through trial and error, however, in recent years there has been an interest in using scientific research to identify ...techniques and procedures that improve the outcome of surgical procedures and determine the effects of tagging on individuals. Here we summarize the trends in 108 peer-reviewed electronic tagging effect studies focused on intracoleomic implantation to determine opportunities for future research. To date, almost all of the studies have been conducted in freshwater, typically in laboratory environments, and have focused on biotelemetry devices. The majority of studies have focused on salmonids, cyprinids, ictalurids and centrarchids, with a regional bias towards North America, Europe and Australia. Most studies have focused on determining whether there is a negative effect of tagging relative to control fish, with proportionally fewer that have contrasted different aspects of the surgical procedure (e.g., methods of sterilization, incision location, wound closure material) that could advance the discipline. Many of these studies included routine endpoints such as mortality, growth, healing and tag retention, with fewer addressing sublethal measures such as swimming ability, predator avoidance, physiological costs, or fitness. Continued research is needed to further elevate the practice of electronic tag implantation in fish in order to ensure that the data generated are relevant to untagged conspecifics (i.e., no long-term behavioural or physiological consequences) and the surgical procedure does not impair the health and welfare status of the tagged fish. To that end, we advocate for (1) rigorous controlled manipulations based on statistical designs that have adequate power, account for inter-individual variation, and include controls and shams, (2) studies that transcend the laboratory and the field with more studies in marine waters, (3) incorporation of knowledge and techniques emerging from the medical and veterinary disciplines, (4) addressing all components of the surgical event, (5) comparative studies that evaluate the same surgical techniques on multiple species and in different environments, (6) consideration of how biotic factors (e.g., sex, age, size) influence tagging outcomes, and (7) studies that cover a range of endpoints over ecologically relevant time periods.
Salmon recovery and the potential detrimental effects of dams on fish have been attracting national attention due to the environmental and economic implications. In recent years acoustic telemetry ...has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing a bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter lasts four times longer and weighs 30% less than other transmitters. Because the new transmitter costs significantly less to use and may substantially reduce adverse effects of implantation and tag burden, it will allow for study of migration behavior and survival of species and sizes of fish that have never been studied before. The new technology will lead to critical information needed for salmon recovery and the development of fish-friendly hydroelectric systems.
In 2001 the U.S. Army Corps of Engineers, Portland District (OR, USA), started developing the Juvenile Salmon Acoustic Telemetry System, a nonproprietary sensing technology, to meet the needs for ...monitoring the survival of juvenile salmonids through eight large hydroelectric facilities within the Federal Columbia River Power System (FCRPS). Initial development focused on coded acoustic microtransmitters and autonomous receivers that could be deployed in open reaches of the river for detection of the juvenile salmonids implanted with microtransmitters as they passed the autonomous receiver arrays. In 2006, the Pacific Northwest National Laboratory began the development of an acoustic receiver system for deployment at hydropower facilities (cabled receiver) for detecting fish tagged with microtransmitters as well as tracking them in two or three dimensions for determining route of passage and behavior as the fish passed at the facility. The additional information on route of passage, combined with survival estimates, is used by the dam operators and managers to make structural and operational changes at the hydropower facilities to improve survival of fish as they pass the facilities through the FCRPS.
A substantial percentage of the Pacific salmon Oncorhynchus spp. and steelhead O. mykiss smolts that emigrate to the ocean each year are smaller than 110 mm (fork length). However, relatively few ...researchers have implanted acoustic transmitters in fish of this size, and none have reported minimum fish lengths below 110 mm for which the tag burden did not negatively influence growth or survival. The influence of a surgically implanted acoustic microtransmitter and a passive integrated transponder (PIT) tag on the growth and survival of hatchery‐reared juvenile Chinook salmon was examined over a period of 30 d. Growth and survival were compared between treatment (tagged) and control (untagged) fish within three size‐groups (80–89, 90–99, and 100–109 mm). The acoustic microtransmitter and PIT tag implanted in our study had a combined weight of 0.74 g; the combined tag burden for implanted fish ranged from 4.5% to 15.7%. The results indicated that growth and survival among implanted juvenile Chinook salmon were size dependent. Significant differences in growth rate and survival were observed between treatment and control fish in the 80–89‐mm group. The survival of implanted fish smaller than 11.1 g (tag burden, >6.7%) and the growth of fish smaller than 9.0 g (tag burden, >8.2%) were negatively affected by the implantation or presence of an acoustic microtransmitter and PIT tag. The results of this study will aid researchers in determining the minimum fish size suitable for use in acoustic telemetry studies that estimate the short‐term (30‐d) survival and growth of juvenile salmonids.
Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitter are key limiting factors. The ...newly developed injectable transmitter is the first acoustic transmitter that can be implanted via injection instead of surgery. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the proceeding generation of commercially-available JSATS transmitters tested concurrently. Snake River subyearling Chinook salmon smolts implanted with the injectable transmitter had a higher survival probability from release to each of eleven downstream detection arrays, because reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The reduction in size and ability to implant the new transmitter via injection has reduced the tag or tagging effect bias associated with studying small fishes. The information gathered with this new technology is helping to evaluate the impacts of dams on fishes.
The Juvenile Salmon Acoustic Telemetry System (JSATS) is an active sensing technology developed by the U.S. Army Corps of Engineers, Portland District, for detecting and tracking small fish. It is ...used primarily for evaluating behavior and survival of juvenile salmonids migrating through the Federal Columbia River Power System to the Pacific Ocean. It provides critical data for salmon protection and development of more "fish-friendly" hydroelectric facilities. The objective of this study was to design and build a Measurement and Calibration System (MCS) for evaluating the JSATS components, because the JSATS requires comprehensive acceptance and performance testing in a controlled environment before it is deployed in the field. The MCS consists of a reference transducer, a water test tank lined with anechoic material, a motion control unit, a reference receiver, a signal conditioner and amplifier unit, a data acquisition board, MATLAB control and analysis interface, and a computer. The fully integrated MCS has been evaluated successfully at various simulated distances and using different encoded signals at frequencies within the bandwidth of the JSATS transmitter. The MCS provides accurate acoustic mapping capability in a controlled environment and automates the process that allows real-time measurements and evaluation of the piezoelectric transducers, sensors, or the acoustic fields. The MCS has been in use since 2009 for acceptance and performance testing of, and further improvements to, the JSATS.
The intracoelomic surgical implantation of electronic tags (including radio and acoustic telemetry transmitters, passive integrated transponders and archival biologgers) is frequently used for ...conducting studies on fish. Electronic tagging studies provide information on the spatial ecology, behavior and survival of fish in marine and freshwater systems. However, any surgical procedure, particularly one where a laparotomy is performed and the coelomic cavity is opened, has the potential to alter the survival, behavior or condition of the animal which can impair welfare and introduce bias. Given that management, regulatory and conservation decisions are based on the assumption that fish implanted with electronic tags have similar fates and behavior relative to untagged conspecifics, it is critical to ensure that best surgical practices are being used. Also, the current lack of standardized surgical procedures and reporting of specific methodological details precludes cross-study and cross-year analyses which would further progress the field of fisheries science. This compilation of papers seeks to identify the best practices for the entire intracoelomic tagging procedure including pre- and post-operative care, anesthesia, wound closure, and use of antibiotics. Although there is a particular focus on salmonid smolts given the large body of literature available on that group, other life-stages and species of fish are discussed where there is sufficient knowledge. Additional papers explore the role of the veterinarian in fish surgeries, the need for minimal standards in the training of fish surgeons, providing a call for more complete and transparent procedures, and identifying trends in procedures and research needs. Collectively, this body of knowledge should help to improve data quality (including comparability and repeatability), enhance management and conservation strategies, and maintain the welfare status of tagged fish.
The miniaturization of acoustic transmitters may allow greater flexibility in terms of the size and species of fish available to tag. New downsized injectable acoustic tags similar in shape to ...passive integrated transponder tags can be rapidly injected rather than surgically implanted through a sutured incision. Before wide-scale field use of these injectable transmitters, standard protocols to ensure the most effective and least damaging methods of implantation must be developed. Three implantation methods were tested in various sizes of juvenile Chinook salmon (Oncorhynchus tschawytscha). Methods included a needle bevel-down injection, a needle bevel-up injection with a 90° rotation, and tag implantation through an unsutured incision. Tagged fish were compared to untagged control groups. Weight and wound area were measured at tagging and every week for 3 weeks; holding tanks were checked daily for mortalities and tag losses. No significant differences among treatments were found in tag loss, or survival, but wound area was significantly reduced among fish tagged via an incision and growth was slightly reduced in bevel down fish. Although there were no significant differences, the bevel-up injection trended toward having the worst results in terms of tag loss and wound area and had high mortality. Implantation through an incision resulted in the lowest tag loss but the highest mortality. Fish from the bevel-down treatment group had the least mortality and smaller wound areas than the bevel-up treatment group but also showed reduced growth. Cumulatively, the data suggest that the unsutured incision and bevel-down injection methods were the most effective; the drawbacks of both methods are described in detail.
This study assessed performance of seven suture types in subyearling Chinook salmon Oncorhynchus tshawytscha implanted with acoustic microtransmitters and held at two water temperatures (12°C and ...17°C). Nonabsorbable (Ethilon) and absorbable (Monocryl) monofilament sutures and nonabsorbable (Nurolon and silk) and absorbable (Vicryl, Vicryl Plus, and Vicryl Rapide) braided sutures were used to close incisions in Chinook salmon. When differences existed among suture types, tag and suture retention were generally highest for monofilament sutures. Wound inflammation and ulceration were generally lower for Ethilon and Monocryl than for most of the braided sutures. In this study, Nurolon (braided) often resulted in low wound inflammation and ulceration, although suture retention was poor. Generally, fish held in 12°C water had more desirable postsurgery healing characteristics (i.e., higher tag and suture retention; lower incision openness, wound inflammation, and ulceration) at 7 and 14 d postsurgery than fish held in 17°C water. On days 34 and 63, tag retention remained high among fish in 12°C water, while suture retention decreased dramatically in both water temperatures. We found a significant effect of surgeon on tag and suture retention, wound inflammation and ulceration, and incision openness. Surgeons in this study were initially thought to have similar surgical proficiency based on their extensive previous experience. However, surgeons who had received feedback on their previous surgical technique performed better in this study. Results indicate that surgical training (i.e., feedback) and perhaps aptitude, rather than surgeon experience alone, may be as important as suture type in influencing the retention of sutures and tags. The overall results support the conclusion that Monocryl is the best suture material for closing incisions created during surgical implantation of acoustic microtransmitters in subyearling Chinook salmon. Future research should include testing different suturing patterns and knotting techniques as well as the number of knots required for different incision lengths.
The size reduction of acoustic transmitters has led to a reduction in the length of the incision needed to implant a transmitter. Smaller suture knot profiles and fewer sutures may be adequate for ...closing an incision used to surgically implant an acoustic transmitter. As a result, faster surgery times and reduced tissue trauma could lead to increased survival and decreased infection for implanted fish. The objective of this study was to assess the effects of five suturing techniques on mortality, tag and suture retention, incision openness, ulceration, and redness in juvenile Chinook salmon Oncorhynchus tshawytscha implanted with acoustic transmitters. Suturing was performed by three surgeons, and study fish were held at two water temperatures (12°C and 17°C). Mortality was low and tag retention was high for all treatments on all examination days (7, 14, 21, and 28 d postsurgery). Because there was variation by surgeon in suture retention among treatments, further analyses included only the one surgeon who received feedback training in all suturing techniques. Incision openness and tissue redness did not differ among treatments. The only difference observed among treatments was in tissue ulceration. Incisions closed with a horizontal mattress pattern had more ulcerations than did other treatments among fish held for 28 d at 17°C. Results from this study suggest that one simple interrupted 1 × 1 × 1 × 1 suture is adequate for closing incisions on fish under most circumstances. However, in dynamic environments, two simple interrupted 1 × 1 × 1 × 1 sutures should provide adequate incision closure. Reducing bias in survival and behavior tagging studies is important when making comparisons with the migrating salmon population. Therefore, by minimizing the effects of tagging on juvenile salmon (reduced tissue trauma and reduced surgery time) researchers can more accurately estimate survival and behavior. Received December 6, 2010; accepted May 4, 2011
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