Great Lakes Fishery Commission

Upstream migrating fish must balance energetic costs with environmental and ecological constraints. Theoretical models predict that fish can conserve energy by adjusting swim speed in response to changing water velocity, but detailed field tests of these predictions remain rare. We used fine-scale acoustic telemetry and hydrodynamic modeling to track adult sea lamprey (Petromyzon marinus) migrating through a river and evaluated how movement speeds varied with environmental conditions and individual traits. Swim speed increased with faster water velocities, while ground speed remained constant, supporting the hypothesis that lampreys regulate swim effort to maintain a fixed migration pace. The average ground speed aligned with a predicted optimum of ~1 body length per second. Both swim and ground speeds declined slightly in deeper water, suggesting a trade-off between movement efficiency and predator avoidance. These findings provide field-based support for a theoretical model of energy optimization and underscore how migratory fish adaptively adjust behavior to local hydrodynamic conditions. Our results highlight the value of using high-resolution tracking and environmental modeling to reveal behavioral tactics that underlie efficient migration strategies.

ABSTRACT Treating Indigenous Peoples as equal participants in decision making requires that groups be prepared to work together in mutually respectful ways. Here, we draw on interviews with Indigenous and non-Indigenous fisheries professionals working for Indigenous fisheries agencies and organizations around the Laurentian Great Lakes (in Canada and the United States) to hear their perspectives on relevant training and learning opportunities that could be helpful to individuals preparing to work in such roles and contexts. We note that participants, most of whom were trained in Western academic institutions and the majority of which were themselves non-Indigenous, felt largely underprepared coming into their roles. We found that the most useful learning opportunities were acquired through mentorship and lived experience on the job. We share reflections on the importance of readiness and training that emerged from the interviews that are useful for individuals who are employed by, or who work in collaboration with, Indigenous groups, such as Indigenous fisheries agencies and organizations. These reflections include a desire for more training on Indigenous history, issues, and culture, which are useful for future fisheries professionals no matter their employer. However, participants also described how personal behaviors, such as genuine intentions, respect, openness, and honesty, are necessary to translate learning into meaningful action. Collectively, the outcomes from this study have the potential to transform not only formal educational opportunities and professional development, especially for non-Indigenous people wishing to work with and for Indigenous Nations, but also set expectations for individual responsibilities and reframe the way in which Indigenous knowledge systems are bridged with Western science and treated by all fisheries professionals.

Evaluating passage performance at migratory barriers is essential for managing connectivity within a watershed and is essential for improvements to fish passage and, in some cases, with invasive species control. To quantify upstream passage opportunities at barriers with complex geometry, a 3-D stochastic leaping model that couples species-specific behavior with hydraulics derived from Computational Fluid Dynamics simulations is developed. The model expands on traditional ballistic-trajectory models to evaluate attempts from any location downstream of a barrier and integrates stochastic variation in fish characteristics—including body length, launch speed, and leap origin—while maintaining computationally-derived local velocity and depth inputs in three dimensions. The revised model provides a spatially detailed assessment of conditions most conducive to successful leaping attempts, offering a more comprehensive evaluation of conditional passage probability at migratory barriers. Applied to two case studies (Union Street Dam—calibration; FishPass arc–labyrinth and low-flow weir—design), the model predicted conditional passage probabilities ranged from < 1% at base flow to ~ 10% at a 200-year flood. Results highlight how barrier geometry, tailwater depth, and flow cues shape leaping success, providing actionable guidance for either facilitating desirable passage or strengthening migration barriers.

Sea lamprey (Petromyzon marinus) control in the Laurentian Great Lakes of North America is among the largest and most successful control programs of an invasive species anywhere on the planet. The effort began more than 75 years ago; it unites multiple nations, states, and provinces with the common goal of controlling this invasive species and protecting a valuable fishery. The science-based control program is administered by the Great Lakes Fishery Commission (GLFC), a body arising from a treaty signed by the United States and Canada. In the present article, we share 10 lessons learned from decades of successful sea lamprey control with the hopes of informing ongoing and future control programs targeting biological invasions. The 10 lessons we identified are to act boldly in times of crisis, to maintain the social license, to invest in capacity building, to break down the silos, to support fundamental science, to diversify your portfolio of control measures, to strive for continuous improvement, to confront the trade-off between information and action, to keep your foot on the gas, and to keep your eyes on the prize. The GLFC has long fostered a framework that uses some military strategy and verbiage that extends across the lessons (e.g., know your enemy). Other lessons are more nascent as the GLFC reenvisions its relationship with Indigenous peoples and governments in a path to reconciliation where two-eyed seeing is being embraced. Through adaptive management, horizon scanning methods, and embracing implementation science, the lessons learned about sea lamprey control will continue to evolve, which is itself a lesson. We submit that the lessons shared in the present article will help guide invasive species control programs spanning taxa, ecosystems, and regions.

Dam removals and fish passage can enhance aquatic connectivity but may also promote upstream transport of legacy contaminants by migratory fish. This study assessed the potential for contaminant biotransport in Michigan's Boardman River following the planned removal of the Union Street Dam and installation of FishPass, a selective fish passage facility. We quantified polychlorinated biphenyls (PCBs), mercury (Hg), and organochlorine pesticides in carcass and egg samples from migratory species including Chinook and coho salmon, migratory rainbow trout, common white and longnose sucker, lake trout, walleye, and sea lamprey. Chinook salmon exhibited the highest PCB concentrations in both carcasses and eggs, exceeding those of rainbow trout and native suckers. Similarly, Chinook salmon were predicted to deposit up to 2,200 mg PCBs upstream under a high run size scenario, over 80 and 100 times greater than rainbow trout and native suckers. Although suckers had lower individual contaminant burdens, their relatively large run sizes contributed moderately to potential contaminant biotransport compared with rainbow trout, indicating an interaction between abundance and spawner contaminant burden. Stream-resident brook and brown trout in reaches open to migratory fish had higher PCBs and lower Hg concentrations than in closed reaches, likely reflecting dietary exposure to eggs and growth dilution. These results demonstrate that the potential for contaminant biotransport varies widely among migratory species and highlights the need for managers to consider both contaminant burden and run size when making fish passage decisions to balance ecological restoration with contaminant exposure risk.

This research paper presents a novel approach to fish surveillance, specifically detecting fish jumping out of water, by leveraging deep learning-based object detection techniques. The study focuses on the use of an EfficientDet-Lite model, a lightweight and efficient model suitable for edge computing devices. The model was trained using a machine learning pipeline that significantly reduces the amount of data requiring manual review. The performance of the model was evaluated using standard average precision (AP) metrics and manual image- and clip-based evaluation. For the TFLite model running on the GPU, the precision derived from the manual evaluation was 0.841 and the recall was 0.279. For the same model compiled for and run on the Coral Edge TPU, the precision was slightly lower at 0.838 with a recall of 0.274. In the clip-based evaluation, the Edge TPU in the Frigate environment achieved a precision of 0.030 and a recall of 0.11. Although the AP metrics appear relatively low, the model demonstrated a high capacity to accurately detect and approximate the location of fish, which is the primary objective of this research. The model was further evaluated in a simulated production environment, demonstrating its potential for real-time fish detection during jumping events. Overall, this study contributes to the field of fish surveillance by introducing an efficient and effective method for fish detection. This research serves as a proof of concept for fish emergence observation using object detection.

Abstract Coregonus populations across their Holarctic range have often undergone unexplained collapses. Here, we document causes of collapse for two of the largest Coregonus populations in the world, cisco (C. artedi) in Green Bay, Lake Michigan, and Saginaw Bay, Lake Huron, during the 1950s. We used simulation models, rank‐order correlations, and historical literature to evaluate effects of overfishing, interactions with introduced rainbow smelt (Osmerus mordax), and overwinter bottom hypoxia on both cisco populations. Fully selected exploitation rates for cisco were alarmingly high (0.82–0.84), correlations and anecdotal evidence suggested negative interactions with rainbow smelt, and extensive areas of hypoxia coincident with cisco declines suggested incubation of cisco embryos was impaired regionally. Our findings suggested that negative effects of rainbow smelt were mainly responsible for the cisco population collapse in Green Bay and that overfishing and hypoxia had suppressed the Saginaw Bay cisco population before rainbow smelt caused its final collapse.

In-stream barriers pose threats to fishes, including habitat loss, constraints on migration, and reduced connectivity between populations. Despite many negative consequences, barriers can serve to protect native species by limiting the spread of invasive species. For example, in the Laurentian Great Lakes, physical barriers have long been used to control invasive sea lamprey (Petromyzon marinus) populations by limiting access to potential upstream spawning and rearing habitat. Selective fish passage systems could solve this management trade-off, termed the “connectivity conundrum”, but must efficiently pass multiple native or desirable species while blocking invasive species. Designing such fish passage systems requires an understanding of the attribute dimensions of the fish community, specifically, the phenology, morphology, physiology, and behaviour of each species. Here, we describe the first comprehensive collection of sortable attributes associated with fish passage. The integrated database consists of 21 biological attributes that influence the movement and passage of 220 species in the Great Lakes, including native species, established non-native species, and unestablished but potentially invasive fishes. Data coverage varies with species, taxonomic orders, and attribute dimensions. Behavioural attributes were typically underrepresented in the literature, and the ecology of potential invaders was not well understood. The synthesis described herein is a critical step towards a holistic approach to fish passage design and may help to inform management actions related to population connectivity. The database is openly accessible online and is expected to be updated periodically.