Environmentalists in North America are looking at options to control an invasive species of fish, the Asian carp, which threatens to squeeze out other species if its numbers continue to grow.

Imported as a farmed species in the 1970s, Bighead and Silver carp from China were first seen as a way to produce cheap food, but floodwaters overwhelmed the fish farms, spreading the fish throughout the US Midwest.

The threat from the species is so grave that authorities could end up spending billions of dollars and physically separating two river basins.

Al Jazeera's Daniel Lak reports from Toronto, Canada.