| The St Lawrence Seaway opened the Great | | | | Tanner, a University of Michigan Biologist proposed |
| Lakes to ocean going vessels. Since then 160 | | | | that a predator, the Coho salmon from the West |
| species have invaded the Lakes ecosystem, with | | | | Coast, be introduced into Lake Michigan to control |
| ship ballast water being the primary suspected | | | | the alewife population. Dr. Tanner's experiment |
| pathway causing drastic economic and ecological | | | | was a huge success which eventually led to state |
| changes to the lakes. | | | | salmon/trout hatcheries and annual Spring fish |
| It is thought that improvements to the Welland | | | | plants throughout the lakes. |
| Canal in 1919 allowed the invasive Sea Lamprey | | | | Today, Lake Michigan is a world class salmon |
| to spread throughout the lakes, were it decimated | | | | trout fishery. The invasive Alewife, and the |
| indigenous fish populations such as the Lake Trout. | | | | introduction of the Coho salmon has transformed |
| Another invasive was the Alewife (river herring), | | | | once industrial waterfronts into recreational |
| that had no natural predator, thus exploded in | | | | harbors and revitalized towns around the Great |
| population. In the 1960's the Alewife colonized the | | | | Lakes. Tourists have flocked back. |
| Lakes and became abundant mostly in lakes | | | | Charter fishing fleets have sprung up throughout |
| Huron and Michigan. They often had Summer die | | | | the lakes because of the great fishing. Waukegan, |
| offs, which washed up on the shorelines. | | | | Illinois, once an avoided industrial area, has been |
| These die offs presented the stench of decay | | | | revitalized and was declared, in the 1970's by |
| that closed beaches and resort communities. The | | | | West Port, Washington Captains, the Fresh Water |
| economic losses were staggering throughout the | | | | Salmon Capital of the Great Lakes. |
| lakes communities. To address this disaster, Dr | | | | |