The Hudson River became a science classroom for students from one Brooklyn High School Tuesday.
Bishop Loughlin Memorial High School students teamed up with Cornell University scientists in Chelsea.
It was part of their "Fish Tracker" program.
The students collected DNA samples to identify fish that are on the brink of becoming endangered.
Scientists tell us the students are playing a critical role in their research.
"What we really want is to inspire that next generation of citizen scientists. We want kids to understand and care about their environment. We want them to know they can make a difference," said Dr. Donna Cassidy of Cornell University.
So far 10 city schools have taken part of the program.