Sometimes drastic measures need to be taken to prevent an even more drastic situation, and that is the dilemma today's scientists are facing on the topic of the Alewife, a small silver fish who have wreaked havoc on freshwater ecosystems across Ontario. The invasive species were first spotted in Lake Ontario in 1873, having been carried over in the ballast water of ships. They quickly reproduced in those bodies of water, then bypassed Niagara Falls through the Welland Canal By 1960, they had established themselves in all 5 Great Lakes. Despite being valued as fishing bait and even a human food source, these schools of silver fish are fundamentally altering the Great Lakes ecosystems and doing far more harm than good. Alewives are filter-feeders,
