Duc, Dog and Dan, sorry you guys, but you're wrong. Just got off the phone with the Quinault tribe's net pen manager, and he says they've never clipped the DORSAL off any fish from any tribal facility, and that they are only marking a portion of their steelhead with an adipose clip even now, just to indicate a coded wire tag in their snouts. Also talked to the regional fish bio at Mill Creek WDFW, and he also said they've never clipped dorsals off steelhead from any state hatchery. Like I said, the dorsals do get deformed from hatchery rearing, sometimes to the point non-existence. That's why 12, 15 years ago, and recently on the Hoh as I recall, you could measure the dorsal to determine if the fish was hatchery or wild. It was never because the dorsals were clipped, because they weren't.

Read the regs on the Salmon.

Do you wonder why dorsal fin height is listed as a way to identify hatchery fish?

If they aren't clipping dorsals, then why would their fins be less than 2 1/8" high, or not there at all?

They rub their dorsals off, but their tails and ventral fins aren't worn? Do they swim upside down?

I'll just say that if I'm wrong, it wouldn't be the first time.

Dan, we've all been wrong plenty of times and that's no crime. It's not exactly certain why those dorsals get stubbed in the hatchery environment. I've heard that they get rubbed off on the concrete raceways, and that doesn't seem plausible to me either, and more recently I've heard that it might be a bacterial or infectious thing due to crowded conditions in the raceways. But what is known is that those dorsals tend to weird out on hatchery steehead, and its measurable and that's the reason for the dorsal height regulation. The state actually used to issue cards marking the height that anglers could put up against the dorsal to see if it was a hatchery or wild fish.

In a fish tank it's caused by PH of the water or a bacterial infection.

Duc, Dog, & Dan,

As best as I know, Salmonbelly has this correct. Let's try to keep this civil. I think there are clear explanations for the observations of dorsal fins we all make. State, federal, and tribal hatcheries mark steelhead by clipping the adipose fin, ventral fin, and very occasionally, the pectoral fin.

The Quinault Tribe marks only a percentage of their hatchery steelhead production, which is why many hatchery steelhead in the Quinault, Queets, Salmon have adipose fins.

Deformed dorsal fins are common to most hatchery steelhead, and are a good way to identify hatchery steelhead not intentionally marked. When tested against scale reading some years ago, it was about 85% accurate. Some hatchery steelhead do have "perfect" dorsals, like their wild brethren. Dorsal fins are deformed on hatchery fish due primarily to nipping by other steelhead in the close quarters of the hatchery rearing environment. The dorsal fins, and hearsay has suggested, that some pectoral fins are eroded by rubbing against concrete rearing pond walls. Personally, I've never witnessed the behavior. Further, the net pens used for rearing a lot of hatchery steelhead that end up with similarly deformed dorsal fins, do not have concrete walls.

Hatchery steelhead with deformed dorsals, often do have dorsal fins greater than 2 1/8". I released two last weekend. The "credit card" rule for dorsal fin height is not a very good indicator for hatchery fish, in my opinion. Small wild fish have smaller, but usually perfect dorsal fins. Large hatchery fish with obviously deformed dorsal fins may have dorsal greater than 2 1/8". The NPS has adopted a regulation that was discarded by the state about 20 years ago when they began adipose clipping all hatchery steelhead production.

TK,

Bacterial infection can often lead to fin erosion, but it isn't limited to dorsal fins. Do you have documentation for your statement? I'm not aware of pH being associated with the common occurance of deformed dorsal fins on hatchery steelhead. The pH is about the same in most steelhead streams that I've sampled (6.5 to 7.8), and that covers both hatchery and wild fish rearing environments. How do you associate it with the effect on hatchery steelhead?

Sincerely,

Salmo g.

A bacterial infection that targets one of six fins.......hmmmm. :rolleyes:

I could be wrong, although it would be the first time.

Whatever the cause of the "trimmed" dorsal is, the end result is the same: Right between the mashed potatos and peas.

Okay ... With the science input from Salmo G provided, I think we'll put this to bed.

A last comment from me ... while many think the law is stupid, I've worked with it for ten years in AK and it's not the end of the world.

I think it's a case of a few bad apples spoiling the rest. I'll tell you, I've seen some atrocious handling over the years ... saw one grabbed by the gills yesterday and thrown up on the bank until it was found out that it was a nate and not legal and then thrown back in.

I think it's more of a tool of giving enforcement some options when gross mishandling occurs ... I don't think you're going to see any tix if the fish is 1/2 inch of the water for a pic opportunity. But for those that let 'em flop around the boat for a bit or drag them up into the rocks ... you can now get one and you probably deserve it anyhow