How can we tap the wisdom of the crowd? “Crowd Truthing,” also known as “crowd sourcing” is one approach, in which hundreds or thousands of individuals analyze numerous small segments of very large data sets. The collective findings are then sifted to answer questions no single researcher could hope to tackle alone. This approach is being used with great success to help scientists do everything from classify galaxies to map craters on the moon.

Researchers at the University of Victoria wondered if crowd sourcing might be harnessed to identify and classify fish swimming through Ocean Networks Canada’s many hundreds of hours of underwater video archives. Two biology...