In our Research Highlights blog series, we debut newly published fisheries research by our women of fisheries colleagues. If you have research you would like to highlight and share with our readers, submit a nomination form here!
This Month’s Research Highlight:
Gatch, A.J., S.L. Furgal, D. Gorsky, J.E. Marsden, Z.F. Biesinger, and B.F. Lantry. 2022. Evaluation of post-stocking dispersal and mortality of juvenile lake trout Salvelinus namaycush in Lake Ontario using acoustic telemetry. Journal of Great Lakes Research 48:572-580.
With temperatures searing in much of the northern hemisphere right now, we’re going to try to cool things down a bit. We’re heading to the deep, cold waters of the Great Lakes to talk about a fish with a long history in these waters, the lake trout (Salvelinus namaycush). The species was an important food fish for indigenous people throughout the Great Lakes region, but with European colonization came commercial fisheries, land use changes, and the introduction of the invasive sea lamprey (Petromyzon marinus). By the early 1900s, the species was already in decline and by the late 1950s, they were completely gone from Lake Ontario.
Since that time, lake trout have been stocked in ongoing efforts to re-establish this native top predator and support a recreational fishery in Lake Ontario. Despite these efforts, however, the recreational fishery is dependent on stocking because natural recruitment is critically low. While many impediments to restoration have been overcome, scientists are uncertain why this issue with recruitment still exists. There is some evidence that early life history and changes to vital habitat, such as spawning substrate, may play a role. Reduced habitat quality due to the presence of invasive zebra and quagga mussels, for example, may lead to poor lake trout egg survival and ultimately recruitment failure. That makes this stocking program even more important, as it provides the seed for future generations and the key to recovery of the species.
Photo Credit: Stacy Furgal
And it is stocking that brings us to this research highlight.
This month we are focusing on a group of researchers trying to learn more about what happens after lake trout are stocked and what may be limiting them from reproducing in the wild. Stacy Furgal, a Great Lakes Fisheries Specialist with New York Sea Grant, recently worked with Alexander Gatch of the U.S. Fish and Wildlife Service and three other colleagues on a study that used acoustic telemetry to gather information about the mortality and dispersal of stocked lake trout in Lake Ontario. In all, 38 hatchery-reared, age-1 lake trout were fitted with acoustic tags, a novel approach for these young fish. This allowed researchers to calculate the magnitude and timing of post-release mortality and movements at a much finer scale than previously possible.
Over a 15-month period, mortality of tagged fish was estimated at 26% and researchers found tagged fish stayed in the area for up to two months following stocking. This indicates the stocking area contains favorable conditions for these young fish, but warmer water temperatures and other factors cause fish to later move into deeper habitats. “Using acoustic telemetry allowed us to collect fine-scale movement data and offered some insight into juvenile lake trout behavior that can be used to inform future restoration research, particularly when identifying/evaluating future stocking locations and considering suitable locations for survival of naturally reproduced juveniles,” noted Stacy. Future work will include a lab-based experiment that will evaluate acoustic tag retention and mortality for stocked lake trout that will help researchers improve their estimates.
This work was part of a larger project focused on spawning habitat and egg deposition. Ultimately, in order for the lake trout population to become self-sustaining, obstacles to recruitment need to be identified and overcome. The recovery of the species is at stake, and no one feels that urgency more than the people actively studying and managing this species with that goal in mind. For now, stocking will continue to provide recreational angling opportunities and hopefully lead to the establishment of a naturally recruiting, self-sustaining population.
Stacy will be playing a vital role in communicating scientific information and future work to groups through targeted outreach efforts. “There are many exciting studies that will be happening in the next five years, and I’m thrilled to be able to be a part of such a collaborative effort. My goal is to work with researchers to engage with stakeholders and actively share the results with new audiences.”
Communication, like stocking of lake trout, will be key to recovery.
The full manuscript can be found and downloaded here:
doi.org/10.1016/j.jglr.2022.01.014
My career over the last decade has been laser focused on Great Lakes fisheries and ecology. I’ve bounced between several government agencies in roles ranging from technician to biologist, before finally landing in my current position as the Great Lakes Fisheries Specialist with New York Sea Grant. My strongest ability has always been communication, and with scientific misinformation on the rise, my role as a science communicator feels incredibly important. As a science communicator, I hope that I can become a trusted source of information for my partners and stakeholders within NY’s Great Lakes region, and that I’m able to share fisheries research in a way that is both accessible and engaging.
Photo Credit: Stacy Furgal