This chart shows the number of river herring passing through Upper Mystic Lake Dam on each day in 2016.

Some herring started arriving on April 21, but most did not start arriving until May 9. How do the herring decide when to begin migrating?

During spring, water temperatures begin rising. Could this be a trigger for the herring to start migrating?

Based on this data, it looks like herring only migrate on days when the water temperature is 55 F or higher. Do you think this is true in all years?

Now let's look at the daily herring count along with both water and air temperature for the past five years. Water temperature is only shown in 2016 because it was not measured in the other four years.

How does the start of the migration vary between years? Does air temperature seem to be a factor? In 2016, how are air temperature and water temperature related?

Switch Year: 2012 2013 2014 2015 2016