Was that salmon stocked? For the first time anglers will know at a glance

Fisheries research projects often make use of marked fish. Usually only a proportion of all fish in a lake are marked, but thanks to the Great Lakes mass-marking project, nearly all stocked Chinook salmon in Lake Michigan will have a clipped fin in 2014.

Guidelines for Volunteer Collection of Coded Wire Tags (CWT).
Guidelines for Volunteer Collection of Coded Wire Tags (CWT).

A few years back, I was fishing in the Grand River and came across another angler who was very excited about catching several “wild” steelhead. He was convinced that, because the fish he caught did not have any clipped fins; he was seeing evidence of more reproduction that is natural and a healthier river. I hated to burst his bubble, but the fact of the matter was that a research project had ended a few years before and stocked steelhead were no longer receiving fin clips.

Marking fish using fin clips, tags, or other methods can help shed light on fish movements, the number of fish in a lake, mortality rates, and natural reproduction. Marking fish is expensive, though, and even in fisheries as important as the Great Lakes, it is not often possible to mark a large percentage of fish.

That is where the Great Lakes mass-marking project comes in. The U.S. Fish & Wildlife Service is leading this effort to ensure that a greater percentage of Great Lakes fish are marked. This will provide fisheries managers with a better understanding of fish populations. The project involves clipping the small, fatty adipose fin from fish reared in state, federal, and tribal hatcheries. 

Beginning in 2011, all Chinook salmon stocked in Lake Michigan and U.S. waters of Lake Huron were marked with adipose clips and coded wire tags (CWTs). These tiny tags are injected into the snouts of young salmon before they leave the hatchery. As salmon grow, the position of the tag can change. As a result, the tags in adult fish can be as far back as the eye. While anglers cannot see or remove a CWT on their own, they can recognize a tagged fish by its adipose fin clip. 

Anglers can help biologists and managers to understand the status of salmon fisheries and the role of stocking and natural reproduction by participating in a variety of programs that collect data. Some, like the creel census efforts and “headhunter” collections, simply involve taking some time to talk with state or federal employees that conduct interviews with anglers at dockside. Anglers who are willing to participate, may submit data from all of their Chinook salmon catches for the 2014 season through the Salmon Ambassadors program, which involves measuring each salmon and looking for an adipose fin clip. Finally, if you catch any adipose-clipped salmon or trout, you can remove its head (or snout behind the eye) and submit it to biologists who will excise the CWT and determine where the fish was stocked by reading a microscopic number engraved on the tag. 

Drop-off locations have been set up in Michigan and Wisconsin. Indiana anglers can drop heads off at the INDNR office in Michigan City. Anglers will need to bag each head or snout individually and include a completed data form for each head (Michigan and Indiana use the same form, the Wisconsin form can be found on the Wisconsin DNR website). The completed form can be placed in a sealed bag and then included in the larger bag with the head or snout. 

In the past, Michigan offered free lures to anglers who submitted heads. Due to the much larger number of tagged fish in recent years, the free lures are no longer offered, but Michigan anglers will be notified of the stocking location of each fish they submitted after the end of the season.

For additional information about tagged fish:

Southwest Michigan Sea Grant News (Perch Summit videos and Salmon Ambassadors info)

Michigan Sea Grant YouTube Channel

Michigan DNR Coded Wire Tag Program (includes map with tag return info)

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