Salmon Bracelets

This is a cool way to motivate kids to explore their local stream ecosystem and think about how salmon or trout are connected not just to the stream and water, but all different aspects of the ecosystem.

How would you modify this activity for a trout stream where no salmon are present?  Has anyone done anything like this before?

http://www.troutintheclassroom.org/teachers/library/salmon-bracelet-learning-ecosystem