GLEAM

Great Lakes Environmental Assessment and Mapping Project

Native fish stocking

Lake trout fry (USFWS)
Lake trout fry (Image: U.S. Fish and Wildlife Service)

Several important Great Lakes fish species have been severely diminished or extirpated because of over-exploitation, habitat degradation, invasive species introductions, and other ecosystem changes. Native fish stocking has been pursued for the rehabilitation of native fishes and restoration of native fish communities.

Although it is unlikely to be an important stressor, any stocking activity has the potential to introduce disease organisms, alter the population’s genetic make-up and affect species interactions. Lake trout, lake sturgeon, Atlantic salmon and walleye currently are stocked in some locations of the Great Lakes.

Mean Annual Quantity Stocked (2000-2009) by Lake1

Native Species

Superior

Huron

Michigan

Erie

Ontario

Atlantic salmon*

0

0

0

0

230,000

Brook trout

280,000

0

25,000

11,000

0

Lake sturgeon

2,200

0

7,800

0

0

Lake trout

960,000

3,600,000

2,800,000

230,000

780,000

Muskellunge

0

0

8,900

0

0

Splake

200,000

32,000

100,000

0

0

Walleye

9,700,000

1,100,000

2,300,000

260,000

86,000

Yellow perch

140,000

0

0

300,000

0

*Atlantic salmon is a native species to Lake Ontario

Mapping native fish stocking as a Great Lakes stressor

  • Fish stocking data were derived from the Great Lakes Fish Stocking Database maintained by the Great Lakes Fishery Commission (GLFC).
  • Stocking data for native species were obtained for the years 1999-2008 for all lakes.
  • The data, summarized by 10-minute grid cell where they enter the Lakes, were then associated with a point at the center of the cell before propagating the data into the lakes.
  • Dispersal was estimated based on several studies of fish movements, especially lake trout.
    • Lake trout dispersal is relatively limited, with the majority of recaptures of tagged fish occurring within 60-80 km of release. (ADD CITATION)
    • We assumed that only 10% of stocked native fishes dispersed more than 50 km, and only 1% went as far as 100 km.

 

Spatial distribution of non-native fish stocking as a stressor in the Laurentian Great Lakes (Inset: Northern Lake Michigan).

Web_20_NativeFishStocking.jpg

Data Sources: 

1. U.S. Fish and Wildlife Service and Great Lakes Fishery Commission. 2010. Great Lakes Fish Stocking database. U.S. Fish and Wildlife Service, Region 3 Fisheries Program, and Great Lakes Fishery Commission.