We established our experimental guppy populations with fish that were individually marked and genotyped.  We perform mark-recapture censuses every month to identify survivors, plus mark and genotype all new fish  that are approaching maturity.  Here we show the entire process of the monthly census.

First, David Reznick provides an overview of this part of the project.

Former graduate students Corey Handelsman and Andrew Furness demonstrate collecting guppies for the mark-recapture.

Captured guppies are put in buckets and David offers some details about how the guppy populations fared in the early phase of the experiment.

Former graduate student Sarah Fitzpatrick and field manager Justa Heinen elaborate on the collection process.

Some guppies go into hiding during the census. Sarah shows how we go after the elusive guppies.

Back in the lab, we process the guppies in an "assembly-line" fashion.

A key part of the processing line is the marking station. Justa demonstrates guppy marking.

After their time in the lab, the guppies return to the stream.