Fish migrations — the whys, whens and types/Tom Rozich
During my travel back from the Detroit Tigers spring training camp and the warm south to the Copper Country tundra, my mind was searching for a subject for March’s column. However, with my head filled with baseball sounds and sights, no topic popped up, until speaking with a fellow birding enthusiast (Thanks, Wendy), who was concerned about sand hill cranes and the timing of their migration. So, fish migrations and movements is the topic, which is also affected by our brutal winter weather.
Fish migrations or movements are made basically for one of three reasons: Reproduction (spawning), feeding, or refuge (best habitat). They can be daily or annual and either horizontal or vertical. Movements can be from a few feet to thousands of miles.
Most anglers think of migrations as fish on their annual spawning run. These are the primary reason most species move. Salmon move thousands of miles from the Pacific Ocean up their birth streams to reproduce. Sockeye salmon travel 2,250 miles up the Yukon River in Alaska to spawn. This kind of movement is termed andromous, moving from salt to fresh water. Our Great Lakes salmon may travel up to 50 miles to spawn. This movement within fresh water is termed potamadromous.
American eels are the North American champions of migrations. As adults, they move from streams along the Atlantic Ocean coast to the Sargasso Sea to spawn, a distance of up to 4,000 miles. This type of movement is termed catadromous, moving from fresh to salt water. They are the only fish in North America to do this. Lake Ontario has a population of eels and they are occasionally found in Lake Huron.
What triggers these migrations? Typically it is a combination of photoperiod (length of day), water temperatures, and water levels. My experiences with such species as steelhead, Coho salmon, Chinook salmon, walleye, pike, and lake sturgeon indicate water temperatures and levels are much more important than photoperiod. The length of day may cause them to stage, but the actual run is triggered by water temperature and level. This means local anglers will have to wait much longer this year for steelhead runs, with our freezing temperatures and mountains of snow.
Daily fish movements are typically for feeding purposes. These horizontal movements can vary from a few feet to miles. A trout will have a daytime hiding place, typically in dark woody cover, but will move a short distance to feed in mid-stream at night. Large brown trout will move several miles to feed at night. Telemetry studies on the Au Sable and Manistee Rivers in the Lower Peninsula have shown large browns travel miles at night to forage, but return to the same daytime cover. This author has had some great fishing at night on these rivers casting large mouse pattern flies.
Similar studies on Siscowet (fat) lake trout, which typically live in 400-600 feet of water, show they migrate vertically in the water column to feed on the surface. Walleye move from their dark daytime deep water haunts into 1-3 feet of water at night to chase minnows. My son thought it was crazy to cast body baits at the Lake Mitchell swimming beach, from shore, until he hooked a 3-pound walleye on his second cast.
The third type of movement is to seek refuge, which means better habitat. This can be for several reasons.
One is to seek thermal refuge, which in most cases means colder water. Brook trout studies have shown they are highly migratory seasonally. During the summer they will seek 68-degree water, which is their optimal temperature. Anglers that learn where these spring holes are catch a lot of brookies. These telemetry studies have shown brook trout will also move to a better winter habitat, typically downstream to warmer water. Fish also seek refuge from pollution, either chemical or thermal. The former can come from an outfall from a factory or municipality. The latter can be caused by a dam which draws water from its top layer.
Understanding fish movements can make one a better angler and increase catches tenfold.