Monitoring the Fish of Crater Lake

Rainbow trout from Crater Lake

A Rainbow Trout caught in Crater Lake.


Crater Lake contains kokanee salmon and rainbow trout

  • the introduction of these fish is the greatest human impact on Crater Lake
  • Kokanee exhibit a boom and bust cycle in abundance over about a ten year
    • when the kokanee are abundant certain zooplankton become scarce due to predation
    • the kokanee "eat themselves out of house and home"
  • kokanee vary widely in size and maturity during the boom/bust cycles
    • when the zooplankton prey is scarce size is reduced and fewer reach maturity

Did You Know?