virolinica) and the presence of pigment on the adipose fin
is distinguished from the remaining species of the genus Leporinus by its color pattern of: one longitudinal and discontinuous narrow dark brown stripe running inconspicuously from a vertical through middle of dorsal fin to base of caudal peduncle along lateral line; two or three large dark brown vertically elongated blotches along middle trunk: first at the vertical through dorsal-fin, second anterior to adipose fin and third on the caudal peduncle; mainly in young specimens, 12-13 short transversal dark brown bars meeting small dark brown blotches laterally.
Median dorsal line of trunk with 15-16 scales between supraoccipital and dorsal-fin origin, 11-13 between dorsal fin and adipose fin and 8-9 between adipose fin and upper caudal-fin insertion.
Color pattern of preserved specimens: A lateral and discontinuous narrow dark brown stripe running inconspicuously on lateral line from a vertical through middle dorsal fin to base of caudal peduncle; two or three large dark brown vertically elongated blotches along middle trunk: first vertically aligned with dorsal fin, second anterior to adipose fin and third on caudal peduncle.
(The adipose fin is that small, fleshy fin located between a salmon's tail and its dorsal fin.
See page 67 of the 2003 Oregon Sport Fishing Regulations for additional details on how to tell one from the other - or if you're not sure what the adipose fin looks like.
While most of the released fish were coho with intact adipose fins, that category also includes fish below the minimum size or hatchery coho released by anglers targeting chinook.
But anglers all along the coast were smiling on opening weekend of the "selective coho season" - so-called because anglers must be selective in their harvest, keeping only hatchery-reared coho with a clipped adipose fin.
To avoid getting ticketed, Day says anglers at the dam are releasing about half of the salmon they reel in because the fish have adipose fins that either were not clipped properly at the hatchery before they were released or have partially "regenerated." (Wild Willamette spring chinook are federally protected, so the angling regulations require the release of any salmon from which the adipose fin has not been "completely removed.")
"The water's too high" (on the Willamette River below Dexter Dam); "the water's too low" (on sections of the McKenzie River bypassed by Eugene Water & Electric Board "power canals"); the poachers are snagging salmon; and "too many fish have to be released because their adipose fin wasn't clipped properly."
About the only thing our group found to complain about was the number of fish that had to be released due to what appeared to be either partially clipped or regenerated adipose fins. Half of the six fish we released fell into that category.
The four of us in Eugene guide Todd Linklater's jet sled also boated six other salmon (including two of the day's biggest) which had to be released because they had an adipose fin on their backs.