This "thread" should bring out even more bowls of popcorn....

[Silver Creek]

Dudley,


I wrote:

Sometimes the hatchery fish are fin clipped so they can be identified. This is done to identify fish planted in a certain year so that later studies on survival and growth rate can be done.

You wrote:

I'm late to the party here and frankly I didn't read the whole thread.

I would however like to comment on a statement someone made about stocked trout having clipped fins.


I worked at a state trout hatchery for a short time. (more for the experience rather than the 9 bucks an hour. )
At this hatchery there were 30 indoor tanks that held 30,000 three inch trout each and when these fish reached 6-7 inches, they were netted, weighted, and trucked to outdoor tanks that held 13,000 fish each
Counting out (by weight) those 13,000 trout for each outdoor tank was done by 3 employees. 2 netting, one weighing.
Imagine if someone had to actually handle each and every one of those 900,000 fish to clip a fin !
The man hours involved would certainly not be cost effective, and the stress to the trout would not be at all healthy.
I'm not saying that other hatcheries don't clip a few fins..... but I can't picture it happening in too many.

You assumed that fins are clipped when the fish are adults.

Some studies require that thousands of fins need to be clipped as in the studies below. There are machines that do this and so this is NOT a big deal when the fins are clipped when the fish are FRY and NOT adults.

"The job is bigger at Lake Roosevelt, where 750,000 hatchery rainbows are fin-clipped before being stocked in net pens for rearing and release each year.

....the state acquired several machines. Operated by as few as three people, they can fin-clip 7,000 fingerlings an hour that's two fish a second."

http://m.spokesman.com/stories/2011/...distinguished/


Not every trout has to be fin clipped for all studies.

Only when serial studies are to be performed and even then there is NO NEED to CLIP EVERY fin to gather statistically significant data.

For example, you clip the fin of every 10th fish. Now you plant 2000 fish in the middle of a 2 mile stretch of river. So there are 200 fish with clipped fins but each fish represents 10 fish.

A month later you shock the 2 miles and find 20 fin flipped fish. That means you have a 10% survival rate and 200 of the stocked trout in that 2 mile segment.

Frequently the clipping is done by volunteers and fishing clubs.

http://articles.chicagotribune.com/2...rout-fish-data

https://www.youtube.com/watch?v=ub2lwmDjyKs

http://www.tu.org/events/adipose-fin-clipping