Development of a Novel Telemetry Tag Attachment Method for Understanding Coregonine Ecology, Movements, and Habitat Use

Michael Lowe (USGS, mlowe@usgs.gov); Andrew Honsey (USGS); Benjamin Marcy-Quay (USGS)

Acoustic telemetry is at the forefront of fisheries research and management in the Great Lakes, and the combination of the ever-expanding receiver network coupled with over 25,000 tagged fish across 53 species (since 2010) continues to provide a wealth of critical information. The majority of acoustic telemetry research to date has focused on relatively large, robust species (e.g., walleye Sander vitreus, lake trout Salvelinus namaycush). However, recent advances in tagging technology and methods have broadened the scope of acoustic telemetry research and led to an increase in the number of planned, in progress, and published acoustic telemetry studies focused on smaller-bodied fishes, such as ciscoes Coregonus spp. in the Great Lakes (Klinard et al., 2020; McKenna Jr et al., 2021; Gatch et al., 2023; Kraus et al., 2023, 2024) and elsewhere (Hadden, Smith and Sutton, 2018; Koeberle et al., 2023). While the results from these recent telemetry projects provide important insights into coregonine spatial ecology, they are complicated by high presumed mortality following tagging and release. Coregonines, particularly ciscoes, are susceptible to handling stress (Harper et al., 2012; Dupuis and Sutton, 2014; Smith, McCall and Sutton, 2017; Hadden, Smith and Sutton, 2018) and tag burden (McKenna Jr. et al. 2021) and, as a result, were once viewed as delicate and difficult to tag. In fact, only lake whitefish are considered in the current (and only) version of “Standardized Surgical Procedures for the Implantation of Electronic Tags in Key Great Lakes Fishes” (Cooke et al., 2012). That narrative has shifted in recent years, and short-term survival (i.e., post-tagging) rates regularly exceed 90% for coregonines implanted with intracelomic electronic tags (Hadden et al. 2018; McKenna Jr. et al. 2021). However, considerable mortality can still occur once the tagged animals are released into the environment due to predation or delayed mortality (Kraus et al. 2024), both of which are likely exacerbated by handling stress during the tagging and release procedure. Advances in materials science offer the potential to externally tag fish with minimal handling stress using hydrogels. Hydrogels are a 3D network of hydrophilic polymer chains that are capable of adhesion to a variety of surfaces, including biological tissue (Zhang et al., 2022; Duque Londono et al., 2024). When cross-linked with other polymers, they form a soft, durable disc that conforms to and flexes with the target organism’s body. Londono et al. (2024) recently demonstrated the feasibility of attaching external sensors to marine animals (e.g., squid, jellyfish, lobsters, sharks, and fish) using a hydrogel derivative. Overall, the attachment method was robust, having high tensile strength and minimal effects on animal behavior. More importantly, the hydrogel performed better in colder water and the entire tagging process took 22 seconds. Validation of such a quick-acting, non-invasive attachment method for Great Lakes fishes could eliminate the need for anesthesia, suturing, and prolonged holding for monitoring after tagging, thereby broadening the scope of potential future research. We propose to develop a novel, non-invasive hydrogel tag attachment technique to reduce handling stress and improve both tagging and post-release survival. We will explore the viability of this approach by conducting trials with cisco C. artedi using multiple hydrogels and hydrogel derivatives. We view this work as the low-cost first step in a potentially high-value line of research, with applications that could lead to fundamental shifts in our understanding of Great Lakes coregonines and other aquatic organisms around the world. For example, the reduced tagging time and handling stress associated with hydrogel tag attachment could allow for tagging of particularly sensitive fishes and/or individuals that are captured with damaging gears (e.g., recaptured stocked cisco collected with gill nets). More importantly, hydrogels potentially allow for attaching acoustic transmitters without removing fish from the water, even at depth (Ma et al., 2022) and could open the door for (1) tagging fishes that are virtually impossible to tag effectively using current methods, including deepwater ciscoes, and (2) selectively tagging fishes at key barriers (e.g., FishPass) or other strategic locations.