Summer runs enter the rivers in late April thru the summer. They have a larger percentage of body fat than their winter cousins. They are active feeders in the rivers and are agressive. Their reproductive organs are not yet fully developed, and they do not spawn until winter. The winter runs start running in November thru winter. The winters are ready to spawn when they reach the rivers. Their reproductive organs are fully developed.

Sometimes in winter it is common to catch dark, "run back" (spawned out) summers while catching winters during their peak runs. You'll never catch a winter during the summer.