The Columbia Basin Bulletin –
The initial period after ocean entry for Columbia River basin juvenile salmon and steelhead is when most of the mortality occurs during their lives at sea, so ocean conditions – temperatures and nutrient supplies – during that period are critical to how many of the fish will return to the river as adults one to three years later.
The path the fish take after they enter the ocean makes a difference, according Laurie Weitkamp of NOAA Fisheries’ Northwest Fisheries Science Center, Newport, OR Field Station, especially lately with the “strange” ocean conditions.
Not all salmonids are the same, she said, and collectively that determines their marine survival.
The fish enter at different sizes, ages and times; they go to different areas after they enter the ocean; they even eat different food; and return at different ages and at different times.