Hatchery trout question

Empire · 03-02-2002, 01:14 PM

Hatchery trout question:

I understand that a wild fish can be distinguished from a hatchery fish by the dorsal fin. On a wild fish, the dorsal fin will have straigt rays. On a hatchery fish the fin will have wavy rays.

I also know that the dorsal fin is sometimes clipped on a hatchery fish.

My question is, how do they make the rays "wavy" on a hatchery fish? I doubt it is a genetic thing, as I have read the argument that the fish are genetically identical.

ampersat · 03-02-2002, 02:30 PM

since these fish are raised in concrete holding ponds, their fins will get ragged and scarred from having rubbed against the rough surfaces.

Mad Mikey · 03-02-2002, 04:23 PM

<<
My question is, how do they make the rays "wavy" on a hatchery fish? I doubt it is a genetic thing, as I have read the argument that the fish are genetically identical>>

The messed up dorsal come from beating around in a concrete surrounded pool with a jillion other fish.

Mike

Empire · 03-02-2002, 05:38 PM

Thank you ampersat and Mad Mikey for your responses. Please elaborate on your response. I have seen lots of fish swimming around in hatcheries, and they are definately crowded. The concrete pond liners can definately wear the fins, but it seems to me that the ventral, **** , and tail fins would be worn (that I have seen on fish I have caught). Unless the fish is swimming belly up, how does the dorsal fin get worn? Than-Q!

Empire · 03-02-2002, 05:40 PM

Oh, I guess I cannot use a certain word, because I see that it is all **** in my post above. I should have put "the fin nearest the vent."

STGRule · 03-02-2002, 05:46 PM

When the fish are really crowded they tend to nibble on each others fins too.

Mad Mikey · 03-03-2002, 02:42 PM

<<When the fish are really crowded they tend to nibble on each others fins too.>>

STG nailed it. I worked at a lodge in AK a while back and the owner had a private trout tagging program which he used to prove the rainbows in that system wandered hundreds of miles and helped convince AKDFW to implement C&R on many feeder streams in the system. The interesting part was that they used drab colored tags, no phosphorescent stuff because they found the brighter tags(plastic tube clipped behind dorsal) caused other fish to attack tagged fish at the point of attachment. Some of the big bows we caught with bright tags from the start of the program had lotsa little nasty bite marks on their backs and their dorsals were almost gone. White and grey seemed to stop this.
Just thought I'd throw that in for kicks....