GLEAM

Great Lakes Environmental Assessment and Mapping Project

Non-native fish stocking

Atlantic salmon, brown trout, Chinook salmon, coho salmon and rainbow trout are all currently stocked in one or more of the Great Lakes.

  • Non-native salmonines species were first introduced to the Great Lakes more than 150 years ago, but only the rainbow trout prospered.
  • More recent stocking efforts date back to the 1960s-1970s, following the collapse of lake trout populations and the invasion by alewives and rainbow smelt.
  • Chinook and coho salmon were specifically introduced to control alewives and to create a sport fishery.

 

Mean Annual Quantity Stocked (2000-2009) by Lake1

Non-native species

Superior

Huron

Michigan

Erie

Ontario

Atlantic salmon

0

35,000

0

0

0

Brown trout

179,000

220,000

1,500,000

60,000

600,000

Chinook salmon

835,000

2,300,000

3,700,000

0

1,900,000

Coho Salmon

25,000

0

2,300,000

42,000

360,000

Rainbow trout

859,000

450,000

1,800,000

1,400,000

880,000

Non-native fish stocking has negative and positive impacts on native fishes in the Great Lakes, with the potential to harm both native species and to facilitate the rehabilitation of diminished, threatened, or extirpated native species.

Impacts of non-native fish stocking

  • Non-native fish may compete with native fishes for food and spawning habitat
  • May cause excessive mortality to native prey and competitor species.
  • Stocking may provide vectors for disease and parasite introductions
  • Highly mobile non-native salmonines may disperse native and non-native pathogens and parasites throughout the Great Lakes.

 

Benefits of non-native fish stocking

  • Non-native salmonines provide highly effective control of alewife and rainbow smelt that has facilitated the recovery of native species.
  • Play key role in regional economy through support of profitable sport fisheries.

 

Mapping non-native fish stocking as a Great Lakes stressor

  • Non-native fish stocking data were derived from the Great Lakes Fish Stocking Database for the years 1999-2008.
  • 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 salmon movements, which disperse greater distances than stocked native species. (ADD CITATION) 
  • We assumed that 10% of stocked non-native fishes dispersed 100 km and 1% traveled as far as 150 km.

 

Non-native fish stocking stressor map

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.