Document Category: Tagging and Marking

Fisheries professionals charged with managing muskellunge (Esox masquinongy) frequently seek population information that requires the ability to identify cohorts as well as individuals; hence, reliable tagging methods are needed. Our approach was to simultaneously assess multiple marking techniques on different life stages of muskellunge over short and long time scales. We evaluated the short‐term detection of visible implant elastomer (VIE) and passive integrated transponder (PIT) tags in muskellunge fingerlings in experimental ponds. We compared survival (relative to that of control fish) and tag retention for two PIT tagging locations (the cheek and dorsal musculature) and one VIE location (the jaw). Overwinter survival did not differ between tagged and untagged fish (84–98%), but overwinter PIT tag retention was lower for the cheek (92%) than the dorsal musculature (100%). We also fin‐clipped and VIE‐tagged (jaw) 1,651 muskellunge fingerlings from 1997 to 2002 to evaluate long‐term tag retention in a broodstock lake. In addition, 125 adult muskellunge were captured and PIT‐tagged from 2003 to 2006. Muskellunge were sampled annually with trap nets and electrofishing during spring and fall. Only 2 VIE tags were detected in adults marked as fingerlings. The proportion of PIT‐tagged adults recaptured ranged from 52% to 84% during the sampling period. Our results indicate that both VIE and PIT tags are viable short‐term marks for muskellunge fingerlings, while PIT tags appear to be reliable long‐term tags when implanted in the dorsal musculature of adults.

Fisheries management requires an understanding of the processes regulating populations, including recruitment, growth, mortality, emigration, and immigration. Tagging provides one of the best methods for addressing these questions, and PIT tags represent one of the newest technologies. Passive integrated transponder tags generally have high retention rates and minimal effects on fish growth and survival. Multiple PIT tag sizes are available, but little is known regarding the effects of tag size on tag retention, growth, or survival in fish. Thus, our objectives were to evaluate the effects of three PIT tag sizes (12, 23, and 32 mm) and two implantation sites (dorsal muscle and body cavity) on tag retention, growth, and survival of age‐0 walleyes (Sander vitreus) and muskellunge (Esox masquinongy) . Fish (210 individuals per species per year) were randomly assigned to one of six treatments or a control during 2014 and 2015 and were held for 112 d. Walleye survival was lower in 2014 (87%) than in 2015 (>99%) but did not vary between implantation sites or among tag sizes; muskellunge survival was 100% during both years. Tag retention over 112 d was nearly 100% in walleyes regardless of tagging site or tag size. In muskellunge, tag retention was lower during 2014 (65%) than during 2015 (93%) and was lower when implanted in the body cavity (63%) than in the dorsal muscle (87%); however, tag retention was similar among tag sizes. Walleyes and muskellunge grew little over the winter, and growth was generally similar among fish with different implantation sites and tag sizes. Collectively, our results indicate that PIT tags larger than 12 mm can be successfully used in walleyes and muskellunge and will likely increase the tag detection rates for these species, particularly in studies that use stationary PIT tag antennas.

The development of small acoustic transmitters has enabled researchers to monitor earlier life stages and smaller fish species than was previously possible. The underlying assumptions of any telemetry study are minimal tag loss and negligible effects on the behavior, survival, and growth of tagged individuals. To that end, tag retention, healing, survival, specific growth rates, and behavior were evaluated for 96 age‐0 muskellunge (Esox masquinongy) (TL [mean ± SD] = 205 ± 10 mm) from three treatment groups. Tagged fish were compared to untagged controls and sham fish (fish that had undergone anesthesia and laparotomy but not transmitter implantation). Thirty‐two fish (tagged group) were implanted with one of the smallest commercially available acoustic transmitters (Juvenile Salmon Acoustic Telemetry tag; 12.0 × 5.3 × 3.7 mm, 0.217 g in air, >120‐d tag life) and monitored in a 4‐month, overwinter tank experiment. Tricaine methanesulfonate was used for anesthesia, incisions were closed with a synthetic absorbable monofilament, and all surgeries were conducted by a single trained researcher. All tags were retained throughout the experiment; surgical wounds healed within 30 d, 32% of sutures were retained at 120 d postsurgery, and survival did not differ between treatments. No biologically significant effects of tagging on mean relative growth rates (percent change in weight/d) were observed among the three groups (tagged, untagged, and sham fish) at 4 months postprocessing. The reaction of tagged fish to a moving object within 15 minutes after tagging was slower than the reaction at 7 d postsurgery, reiterating the importance of testing appropriate sedation methods prior to releasing fish in field studies. Results validate the utility of surgical implantation of small acoustic transmitters in juvenile muskellunge for future studies, although immobilization methods for early life stages require further study.

When added to pelleted diets, liquid oxytetracycline (500 mg/kg of fish per day) was effective in marking (after 12 d) and disease treatment (after 3 d) of tiger muskellunge (the hybrid of northern pike, Esox lucius, and muskellunge, E. masquinongy). Liquid oxytetracycline is more easily applied and costs less than traditional methods for these purposes.

Intracoelomic implantation of transmitters into fish requires making a surgical incision, incision closure, and other surgery related techniques; however, the tools and techniques used in the surgical process vary widely. We review the available literature and focus on tools and techniques used for conducting surgery on juvenile salmonids because of the large amount of research that is conducted on them. The use of sterilized surgical instruments properly selected for a given size of fish will minimize tissue damage and infection rates, and speed the wound healing of fish implanted with transmitters. For the implantation of transmitters into small fish, the optimal surgical methods include making an incision on the ventral midline along the linea alba (for studies under 1 month), protecting the viscera (by lifting the skin with forceps while creating the incision), and using absorbable monofilament suture with a small-swaged-on swaged-on tapered or reverse-cutting needle. Standardizing the implantation techniques to be used in a study involving particular species and age classes of fish will improve survival and transmitter retention while allowing for comparisons to be made among studies and across multiple years. This review should be useful for researchers working on juvenile salmonids and other sizes and species of fish.

Mark–recapture studies are an important component of fisheries research and management. Underlying assumptions of such studies include minimal tag loss and negligible effects on the behavior, fitness, and survival of tagged individuals. Passive integrated transponder (PIT) tags are becoming increasingly commonplace, largely because of their small size, ease of implantation, longevity, and reportedly high rates of retention. We evaluated tag retention and survival and growth effects on age‐0 muskellunge Esox masquinongy marked with PIT tags at two implantation sites, the peritoneal cavity and the dorsal musculature, during overwinter trials in Illinois and Wisconsin. For both trials, no significant differences in survival (88.0–89.8%), relative daily growth (0.0006–0.00062 mm·mm−1·d−1), or tag retention (99.5–99.8%) were observed among the two implantation groups and a control group. Survival and tag retention were also similar between trials. Our findings suggest that PIT tags implanted either in the peritoneal cavity or the dorsal musculature are acceptable for use in marking age‐0 muskellunge.

The Rideau River supports an active muskellunge (Esox masquinongy) sport fishery. However, it also faces heavy recreational use and increasing development pressures. Little is known about the specific spawning habitats utilized by this population of muskellunge. This study was conducted by a group of concerned anglers from Muskies Canada Inc. (MCI) to provide an insight into critical spawning habitats used by these fish. External radio tags were attached to ten fish. Immediate catch-and-release survival for the study fish was high. Preliminary results suggests that spawning sites include bays, creeks and river bend areas.

Tiger muskellunge (Esox masquinongy × E. lucius) were marked with magnetic wire tags in the cheek musculature, dorsal fin, and anal fin and later examined with a magnetic wire wand detector in an effort to determine the viability of using tag location as a means of identifying groups of fish. Tag retention was 88.3% in the dorsal fin after 185 d, 99.4% in the cheek after 185 d, and 99.0% in the anal fin after 72 d. Varying tag location appears to be a useful way to identify groups of tiger muskellunge.

Mark–recapture studies require knowledge of tag retention rates specific to the tag types, fish species and size, and study duration. We determined the probability of tag loss for passive integrated transponder (PIT) tags implanted into dorsal musculature, T‐bar anchor tags attached to dorsal pterygiophores, and both tags in relation to years post-tagging for double‐marked adult muskellunge (Esox masquinongy) over a 10‐year period. We also used PIT tags as a benchmark to assess the interactive effects of fish length at tagging, sex, and years post-tagging on T‐bar anchor tag loss rates. Only five instances of PIT tag loss were identified; the calculated probability of a fish’s losing its PIT tag was consistently less than 1.0% for up to 10 years post-tagging. The probability of T‐bar anchor tag loss by muskellunge was related to both the number of years post-tagging and the total length (TL) of the fish at tagging. The T‐bar anchor tag loss rate 1 year after tagging was 6.5%. Individuals of less than 750 mm TL at tagging had anchor tag loss rates less than 10% for up to 6 years after tagging. However, the proportion of fish losing T‐bar anchor tags steadily increased with increasing years post-tagging (∼30% after 6 years) for larger muskellunge. Fish gender did not influence the probability of T‐bar anchor tag loss. Our results indicate that T‐bar anchor tags are best suited for short‐term applications (≤1 year) involving adult muskellunge. We recommend use of PIT tags for longer‐term tagging studies, particularly for muskellunge larger than 750 mm TL.

Catch-and-release fishing for muskellunge is one direct method by which anglers can contribute to the future of quality of their fishing experience and enhance the survival of these trophy fish. Muskellunge fishing club members from seven states participated in tagging studies in an effort to quantify survival of angler-caught and released muskellunge. Data from over 1,600 fish tagged and released since 1976 were examined for this summary. Approximately 17% of these angler-tagged muskellunge were recaptured by anglers. Recapture rates for 578 muskellunge caught, tagged and released by 16 experienced anglers ranged from 22% to 44% and averaged 28%. These rates equal or exceed most muskellunge exploitation estimates reported by fisheries agencies, which indicates excellent survival and tag retention for the fish handled by these anglers. In the future, even more extensive tagging studies on fewer bodies of water may provide even more useful information on the positive effects of muskellunge catch-and-release fishing.