A new study proposes and tests the hypothesis that rivers can act like diverse stock portfolios that dampen variability (PDF).

 

The Moore lab team as well as Fisheries and Oceans collaborators compiled and analyzed an enormous dataset of fisheries catches, water flows, and water temperatures that spanned 30 years from a total of 142 sites located throughout the vast Fraser River watershed.

 

Sites that drained larger catchments had more stable flows, temperatures, and fisheries, with less frequent fisheries crashes and floods.

 

This paper was featured as an Editor's Choice in Science magazine (link) and in the Vancouver Sun (link).

 

Previously, postdoctoral researcher Justin Yeakel, Jonathan Moore, and colleagues used mathematical theory to find that the tree-like branches of river networks may help dampen the population variability of river animals (PDF).

 

Collectively, these findings speak to the importance of considering watersheds as whole systems, connected by the flows of water and migrations of fish. While large free-flowing rivers may have an underappreciated natural defense system against variability, habitat loss or blocked connectivity may erode their stability.