A Trick to Predicting Migration

The Fishscape team, lead by researchers from the the University of Connecticut in Storrs, CT (Mark Urban and Heidi Golden), the Marine Biological Laboratory (Cameron MacKenzie), and the Woods Hole Research Center (Linda Deegan), studies genetically distinct Arctic grayling populations from watersheds that differ in temperature, aquatic connectivity, and sensitivity to climate change. Through genomics, otolith microchemistry, PIT tagging, remote sensing and common garden experiments, the team investigates population genetics, impacts to fish movement patterns and genetic and environmental contributions to performance of fish from different physical environments.

By Heidi Golden

We always find difficulty predicting the Arctic spring thaw due to the variability of this environment, but knowing when the Arctic grayling will begin their spawning migrations presents an even greater challenge.  In order to raise baby fish in our common garden experiment, we must first capture adults on their way to spawning locations within the newly flowing streams.  Ripe with eggs and milt (fish sperm), these adults provide gametes for us to artificial fertilize and raise from eggs to larvae to fry in our local adaptation experiment.  Between preparing our common garden aquariums and setting up adult fish monitoring antennas, we also check the river temperatures daily using iButton temperature loggers.  I set these tiny loggers to record river temperature at 10 minute intervals to help us gauge when the rivers approach spawning temperatures of 4 to 6 degrees C.  Right now, our rivers are still running cold, hovering close to zero, but it won’t be long before the 24 hours of radiant sunshine warms these streams and the grayling leave their overwintering locations en route to spawning grounds.  We will only have a small window of opportunity to capture these fish because when the time is right, then move fast.  But with a little help from our iButtons, perhaps we can make an educated guess at migration timing and nab them!