Midwest Region
Conserving the Nature of America

Basin-wide Fisheries Management
Mass Marking in the Great Lakes

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Automated marking trailers have the capability to mark 60,000 fish in an eight-hour day, amounting to an overall cost savings of 11 percent over manual methods.


USFWS biologist explains how mass marking can provide valuable information on fish movements, survival and performance in the Great Lakes.


"Clipping trailer" tags fish from hatchery raceways.


USFWS Photos

The Great Lakes are one of our most valuable and treasured landscapes. They provide not only diverse habitats for freshwater fishes, but their coasts and tributaries also support a wide range of migratory birds and other wildlife, including many of the threatened and endangered species our agency works to protect.

Twenty-five to thirty million fish are stocked in the Great Lakes annually by tribal, state and Federal fishery programs on the U.S. side alone. An additional 10 million are stocked by the Ontario Ministry of Fisheries Resources. However, there has never before been a multijurisdictional-coordinated program across the Great Lakes basin for evaluating these fish in terms of their performance in the wild or their effects on the ecosystem.

The U.S. Fish and Wildlife Service (FWS) recently initiated a mass marking program to coded-wire tag and mark (finclip) state and tribal hatchery-reared fish, in addition to those fish stocked by the FWS in the Great Lakes. This technique that has been successfully used in the Northwest for marking hatchery-reared Pacific salmon, and is known as “mass-marking” since millions of fish are rapidly tagged and marked each year.

The mass-marking initiative began as the brain-child of the Council of Lake Committees, a group of policymakers for each of the Great Lakes, under the auspice of the Great Lakes Fisheries Commission (GLFC). They saw what mass marking was doing for salmon management in the Pacific Northwest, and wanted to bring that same capability to the nation’s most valuable freshwater resource, not only for salmon but for native species like lake and brook trout.

In 2003 the Council of Lake Committee initiated an implementation task force, co-chaired by Marianne Daniels from the Ontario Ministry of Natural Resources and the Fish and Wildlife Service’s (FWS) Chuck Bronte, to develop cost, equipment, and manpower estimates to implement mass-marking in the Great Lakes, as well as the associated data recovery and analytical capabilities.

“The Service already implements a basin-wide sea lamprey control program and lake trout restoration program, and was well-suited to lead the basin-wide mass marking initiative,” said Bronte, a fishery biologist and data analyst from the FWS’s Green Bay National Fish and Wildlife Conservation Office (FWCO).

The FWS’s Fisheries program already uses coded wire tags (CWT) to evaluate the performance of lake trout raised in Federal fish hatcheries; however, the idea behind the mass marking initiative was to equip the Service with capabilities to also tag State and Tribal hatchery fish.

Coded wire tags are small pieces of metal with numerical codes inserted into the nose of fish that, when recovered, allow fish biologists to look at movements, post release mortality, levels of natural recruitment, wild production and other key factors that influence fisheries management.

“It’s important for managers to know how many wild fish are out there, gauge the impact of the stocked fish, and balance forage availability with the number of salmon and trout that are out there,” said Bronte. “It’s also a way to manage non-native species that are naturalized and part of the system, and consider them in relation to native species management like lake trout and brook trout.”

The implementation task force visited each hatchery across the Great Lakes, to determine species and production schedules with the intention of mapping out equipment profiles.

The task force determined that the use of Northwest Marine Technology’s computer operated automated marking trailers would have the capability to mark 60,000 fish in an eight-hour day, amounting to an overall cost savings of 11 percent over manual methods. The automated trailer also provides better tag retention, more consistent tag placement, and easier tag recovery in the laboratory.

A Great Lakes Regional Marking Committee was established to oversee mass marking activities, and includes members from the States, Tribes, Province of Ontario and FWS. The Great Lakes Regional Marking Committee approved this year a project to mark all Federal lake trout in Region 3 (around 5 million fish) and assist with a validation study that examines natural reproduction by tagging 1.2 million of those fish with oxytetracyclene. The FWS also funded a Chinook salmon tagging study by New York Department of Environmental Conservation, which will evaluate the relative survival of pen-reared fish versus those grown out in the hatchery and released from trucks.

This spring the FWS, working with state hatchery personnel, tagged and marked 370,000 Chinook salmon from Wild Rose State Fish Hatchery, and 750,000 Chinook salmon at Platte River State Fish Hatchery, operated by Michigan Department of Natural Resources. The goal for the mass marking program is to reach more than 20 different facilities across the Great Lakes basin.

“Tribal treaty fisheries, inter-jurisdictional fisheries management, and native species restoration and conservation strategies rely on the exchange of information among management jurisdictions,” said Bronte. “Mass marking will improve our knowledge of fish movements, survival, performance and other valuable information about Great Lakes trout and salmon, and will promote cooperative strategic fisheries management.”

Ashley Spratt, External Affairs

Last updated: February 12, 2013