Background
Migratory fish are species that move to accommodate their reproductive, feeding and refuge needs. Many fish migrate during only a small period of their lifetime. For several fish, migration takes place annually on a seasonal basis. Fish can migrate between marine and fresh water (diadromous fish) or between different fresh waters (potamodromous fish).
In the Great Lakes region, migrations are potamodromous and take on several different patterns. Some species, including Lake Sturgeon, Walleye, and Coaster Brook Trout migrate longitudinally from lakes to tributaries to spawn. Others migrate from lakes to coastal wetlands to spawn, like the Northern Pike. There are also species, such as the Lake Trout, that migrate from pelagic areas to near shore and off-shore spawning reefs. Not all migrations cover long distances, migrations by Great Lakes species range from 10s of meters to upwards of 200km. The following table summarizes a subset of Great Lakes migratory fish and their coarse migratory behaviors:
| Common Name | Scientific Name | Most Commonly-Referenced Migratory Behavior |
| American eel | Anguilla rostrata | Between lake and river |
| Atlantic Salmon | Salmo salar | Between lake and river |
| Bluegill | Lepomis macrochirus | Within river |
| Brook Trout | Salvelinus fontinalis | Within river |
| Channel Catfish | Ictalurus punctatus | Within river |
| Lake Herring | Coregonus artedi | Between lake and river / within lake |
| Lake Sturgeon | Acipenser fulvescens | Between lake and river |
| Lake Trout | Salvelinus namaycush | Between lake and river / within lake |
| Lake Whitefish | Coregonus clupeaformis | Between lake and river / within lake |
| Longnose Sucker | Catostomus catostomus | Between lake and river |
| Northern Pike | Esox lucius | Between lake and river |
| Shorthead Redhorse | Moxostoma macrolepidotum | Between lake and river |
| Walleye | Sander vitreus | Between lake and river |
| Source: Great Lakes Inform: An Information Management & Delivery System, https://greatlakesinform.org/knowledge-network/758 | ||
Role in Great Lakes
Migratory fish play important structural and functional role in the Great Lakes. They influence the Great Lakes through direct and indirect mechanisms as consumers, ecosystem engineers, modulators of biological and chemical processes, and transport vectors (Flecker et al 2010). For example, species moving from one area to another move nutrients and energy between and among lake and riverine habitats. When fish or unfertilized eggs decompose, those nutrients are then available to the local foodweb.
Threats to Migratory Fish
- Tributary connectivity. Barriers that restrict upstream movement, such as dams and road crossings, can limit migration. If fish are unable to migrate to an ideal spawning habitat, they may be forced to spawn in sub-optimal conditions that result in reduced egg survival.
- Habitat degradation. Poor land-use practices in surrounding watersheds and pollution from urban or industrial sources contaminates migratory fish habitat.
- Invasive species. Invasive species stress migratory fish through competition and associated shifts in food web dynamics. They can prey on native fish and potentially out-compete native fish for food sources, resulting in sub-optimal diet for native fish.
Conservation Efforts
Several agencies are working to combat threats to migratory fish. These efforts include restoring tributary connectivity by removing dams, improving road crossings, and constructing fish passageways around barriers. Efforts also include restoring habitat by returning forest cover to riparian zones, recovering key native migratory fish species by stocking hatchery-reared fish and restricting harvest, and stopping the spread and controlling established invasive species.
Tracking Migratory Fish in Lake Erie
Tracking migratory patterns of fish is important for conservation efforts. The Great Lakes Fishery Commission established the Great Lakes Acoustic Telemetry Observation System (GLATOS) in 2010, with the goal of understanding fish behavior in relation to Great Lakes ecology and to provide useful information to fish managers. Acoustic telemetry is used to track fish movement. An acoustic tag that transmits a unique signal is implanted in the target species, and an acoustic receiver is used to decode the signal (Figure 1). Some transmitters can incorporate biological and environmental information such as pressure (to determine depth), temperature, and acceleration (to determine swimming behavior). Lake Erie migratory fish projects shared on GLATOS include studies of Lake Sturgeon, Muskellunge, Walleye, Grass Carp, Lake Trout, Sea Lamprey.
Figure 1: Acoustic tag and receiver. Source: http://glatos.glos.us/projects.
Case Study: Assessing adult Muskellunge movement in Buffalo Harbor, Lake Erie, and the Niagara River
Recently, Justin Brewer from the New York State Department of Environmental Conservation and the Niagara Musky Association partnered with the Habitat Enhancement and Restoration Fund to determine migratory patterns of muskellunge in Buffalo Harbor, Lake Erie, and the Niagara River. Knowledge of the seasonal use of these areas will help fishery managers better understand the habitat requirements of Muskellunge and will be used to direct habitat restoration projects. They are using the GLATOS array to document Muskellunge movement. Electro-fishing techniques were used to secure 10 viable musky samples from the Niagara River and Buffalo Harbor, 5 males and 5 females. Acoustic tags were surgically implanted into the musky and 6 acoustic receivers were planted to track them. These receivers are few of many that are updated to the GLATOS database, so if a musky is picked up outside of their study region, it will be detected. This is an ongoing study that will answer important questions about prime Muskellunge spawning habitat, viability, and whether it can be expanded.
References
Great Lakes Inform: An Information Management & Delivery System. Migratory Fish. Available at https://greatlakesinform.org/knowledge-network/758 (Last accessed 29 October 2017).
Great Lakes Acoustic Telemetry Observation System. Available at http://glatos.glos.us/ (Last accessed 29 October 2017).
The Buffalo News. Why this musky study is an investment in the future. Available at http://buffalonews.com/2017/06/14/musky-study-investment-future/ (Last accessed 29 October 2017).
Flecker AS, McIntyre PB, Moore JW, et al (2010) Migratory Fishes as Material and Process Subsidies in Riverine Ecosystems. American Fisheries Society Symposium 73:559–592.