What happens to Steelhead when they reach a mature age that makes them so sensitive to having the protective slime removed from being touched by anglers?

When a smolt gets the Adipose clipped it must get some of the slime removed from handling. Not to mention having the adipose clipped off and raw flesh exposed to the elements.

I believe what I have read from Biologists about the removal of protective slime being harmful to the fish but am curious as why it does not seem to affect the smolts?

Mother Nature put all of those body parts on her fish for a reason, then along comes man and cuts them off!

Just one more "biological reason" why hatchery fish don't survive as well as wild unmarked smolts do. I don't exactly know what each fish fins function performs, or plays in its survival, but you could easily assume its like cutting off your big toe! You can keep walking and running, but you will never have the same kind of balance as you had when it was attached. You don't see very many track runners breaking records that have a missing big toe.

Cowlitzfisherman

Steelhead and salmon are normally fin-clipped when they are fingerlings, not smolts. A better analogy than cutting off a big toe would be removing an appendix. The adipose fin is a vestigial fin that no longer performs any useful function.

We all have hope for you too!

Some just take a little longer to come full circle

You'll get there someday Jerry


Cowlitzfisherman

There is always hope. I hope we all catch some fish.

But getting back to Vistigial... or Vestige...

"A rudimentary or degenerate, usually nonfunctioning, structure that is the remnant of an organ or a part that was fully developed or functioning in a preceding generation or an earlier stage of development."

--- --- ---

I like that. What a wonderful word for describing some aspects of steelhead that have returned to fresh water. I'll try putting it in a sentence.

"Upon entering fresh water the digestive tract of the wild steelhead shuts down becoming vestigial and valuless in its lack of functionality and should be discarded before releasing the fish so it will not encumber the fish in it's migration."

Or...

"In conformance with the new rule that fish required to be released not be completely removed from the water the vestigial digestive tract must be left in the water when releasing a wild steelhead to the cooler."

I wonder if the adipose is like our wisdom teeth. At one point in time they served a purpose, now they are no longer needed. Or at least that is what my dentist told me before he yanked all four of mine and went on a vacation to Hawaii.

Lead thrower

I see that you are around 30 years old. If you were "older" you might understand just how important those "wisdom teeth" can be. They don't make you any "smarter", but if you were to loose those "dumb funchional molars" located just in front of those unneeded wisdoms, I am sure you would understand why they where located there (the big old picture theory)

There are reasons why species like sharks have several rolls of teeth that keep replacing themselves when other are lost!


Cowlitzfisherman

The adipose fin does have a function, when a fish makes a fast acceleration, in speed or change of direction, that little fin is doing a job. That being said, you need to look at the costs to benefits of any "marking" strategy. How else can you externally mark a fry/smolt so you can easily identify it as an adult? They have tried some branding techniques but the adipose fin clip is pretty easy. Sure there is an associated mortality throughout their lifespan, but frankly, so what? As far as the handling and slime removal thing goes, when you are marking fry/fingerlings/smolts your are handling growing critters with, presumibly, healthy biological defense mechanisms. Returning spawners biological systems as they enter the river are placing priority on producing eggs/sperm and reserving energy for travel and spawning which is a big draw on their anti-inflamatory response. If you remove their slime they have little energy to replace it. See Sparky's Law!

Cripes Cowman I'm on my 3rd trip around the circle. I didn't realize I was supposed to stop at the beginning.

CFM

So my dentist was just after another trip to Hawaii

Beezer
Hey my light bulb just turned on

when mass marking fish you don't clip smolts. They are fry. They also don't have scales yet, so I think that has something to do with it. Just my opinion.

pimpinshrimp

As far as I know, they don't clip hatchery "fry"

Cowlitzfisherman

I think it would be more precise to say that they are clipping "parr"...these fish are definitely too old and too big to be fry, or they would be way too small to clip.

Juvenile fish go through a physiological change that immediately precedes their transfer from fresh to salt water, interestingly enough called "smoltification". Many fish released from a hatchery may be as much as a year away from becoming "smolts".

So...now that we know that they aren't really releasing smolts, at least not all the time, and that they definitely weren't smolts at the time they were clipped, what does that do to answer the question?

Nothing, really...but they're definitely "parr" at the time of clipping.

Do parr have slime/scale damage during the clipping? Maybe, but the water they're put back into is generally pretty clean. I think they used to put them through a quick antibiotic wash right after clipping, but I don't know if they still do or not.

At that life stage they are also in full possession of their immune systems, which as was noted above, adults returning are not.

These little guys have three different stages of scale/slime...juvenile fresh water, saltwater, and adult fresh water. They are at their physiological touchiest at the transitions; they are not at a transitional stage at the time of clipping.

While there's no doubt that some handling damage must occur during clipping, my guess is that the extent of damage generally occurring is a lower amount of damage that has a lower impact at the time of clipping, versus handling at a transitional stage, where the damage would be both more extensive and of a higher impact.

Fish on...

Todd

Thanks Todd

One thing for sure, it amazes me how tuff the little guys are. It's a wonder any of them make it back.

Anyone know how long after the clipping until they are released?

LT,

Generally, fin clipping is done from the fall through February, with smolt releases beginning around mid-April. The fin clipping is done when water temperatures are cool and the juvenile fish don't have loose scales. Loose scales are associated with smoltification. So there is a good amount of time for the marking scar to heal before the fish smolts and begins its seaward migration.

Mortality associated with fin clipping and coded-wire-tagging is typically less than 1%. Fin clipping and tagging juveniles while they are smolts is higher, depending on species, water temperature, and handling. It could be as little as 1 or 2% with coho and as high as 10 or 20% with sockeye or spring chinook smolts. You can see why it's generally preferable to avoid marking and tagging smolts, but sometimes that's the only way to obtain a mark group of wild fish.

Sincerely,

Salmo g.

Salmo

Same numbers for fall chinook???

CFM,

I don't have any personal experience with a fall chinook project. My understanding is that spring chinook, like sockeye smolts, are super-sensitive. I cannot account for any difference that might exist between relative sensitivity between spring and fall chinook smolts. I hear that fall chinook smolts are handled in large numbers at the juvenile fish sampling facilities at McNary Dam during June and July when the water temperatures are really on the rise. There probably are mortality estimates for the sampling work that occurs there, but I'm not familiar with any.

If you're interested in the potential effects of chinook handling on the Cowlitz, I'm most concerned about those chinook that migrate through Cowlitz Falls during July and August. The historical data indicate that migrations through that area were during the spring and fall, when temperatures would have less adverse effect. We'll have to see if the off-spring of natural chinook spawners exhibit a better migration timing. I'm expecting that they will.

Sincerely,

Salmo g.