Coho Fry Question

[pennel]

I have a ditch on our property which fills up with water from Oct. to May and then it dries out.
Every year I catch about 3000 coho fry that become landlocked and put them back into the river.
In the mix of fry which varies from smolts to a lot of fry that are about 1-11/2 inches long.
My question is,are these small fry likely born in the ditch or have they migrated from the river?
The ditch is a windy 500 yards long before it enters the river.
Have never seen any salmon activity in the ditch although it's hard to see because of water clour.

 

[Derby]

what river system ?

 

[agentaqua]

Coho fry often travel by getting displaced during flood events from reaches farther upstream and find "refugia" wherever they can (sidechannels, beaver sloughs, ditches, etc.). Many larger systems often end-up with coho fry in tribs with no spawning habitat because those tribs have become "refugia"; and in systems with lagoons and freshwater on the surface, coho fry end up entering small tribs with no spawning neither but got flushed out of a larger watershed and found refuge afterwards. The 1st YO YOY are particularly prone to this because the larger, older fry and trout chase them out of deeper, holding pools and they have comparatively weak swimming ability.

So short answer - likely migrated. Good questions & observations!

 

[pennel]

what river system ?

Somass

 

[Stosh]

I have a ditch on our property which fills up with water from Oct. to May and then it dries out.
Every year I catch about 3000 coho fry that become landlocked and put them back into the river.
In the mix of fry which varies from smolts to a lot of fry that are about 1-11/2 inches long.
My question is,are these small fry likely born in the ditch or have they migrated from the river?
The ditch is a windy 500 yards long before it enters the river.
Have never seen any salmon activity in the ditch although it's hard to see because of water clour.

Pennel
Thanks for looking after the fry.
Stosh

 

[pennel]

Pennel
Thanks for looking after the fry.
Stosh

Thanks ,I figured that instead of just taking from the system I have the opportunity to put something back.
Every little bit helps even if only one comes back.

 

[Stosh]

I help out as a volunteer Streamkeeper on Craigflower Creek in View Royal. The creek is over 12 k’s Long. Mature fish can spawn anywhere that seems to work best once they find gravel beds suitable. Often in summer months fry are found in pools throughout the Creek. We work all summer try to maintain water flow from various lakes to insure there is enough for the fry to survive. This often means opening blockages caused by high water, fallen trees/branches, working with local governments to release water from lakes where possible and getting help/permission from local land owners with large water reserves. Now with the recent discovery of how tires are adding to the problem, we need to find a way to reduce this contamination.
So we can all help like Pennel to keep the waterways flowing and saving more fish in our local systems.
My 2 cents
Stosh

 

[Bryan Allen]

Often ditches and very small streams have a small amount of ground water in them. That is like a magnet to young fish as its warmer. Even 1/2 a degree will pull them in.

 

[Dave]

Often ditches and very small streams have a small amount of ground water in them. That is like a magnet to young fish as its warmer. Even 1/2 a degree will pull them in.

Good point about warm water attracting fish. Another thing to remember when attempting to help stranded fry ... most times the water temperature in the area of concern is warmer, sometimes much warmer, than the recipient stream or river. The stress of handling the fry during capture, and a sudden drop in water temperature, is often enough to kill the fry. It's a fine line and tough call sometimes.

 

[agentaqua]

altho its an easier adjustment going from hot to cold verses the other way around...

Which also opens the discussion up to cold water refugia in the summer and how important it is.

 

[pennel]

Good point about warm water attracting fish. Another thing to remember when attempting to help stranded fry ... most times the water temperature in the area of concern is warmer, sometimes much warmer, than the recipient stream or river. The stress of handling the fry during capture, and a sudden drop in water temperature, is often enough to kill the fry. It's a fine line and tough call sometimes.

Well,if you have any pointers on how to help stranded fry I’ll be ready to take it on-board.
In my particular case there doesn’t seem to be any option as stranded means running out of water.
May be you have something on handling.
The fish I catch is done by using fry traps and walking in the ditch with a net.
The fish are put in a 5 gal. bucket,taken to the river and scooped out at roughly 4 at a time with an aquarium net so that they can be counted.
The catch process is done early morning before the sun gets going and they are no longer than an hour in the bucket .
Normal daily catch is around 200.

 

[Dave]

Well,if you have any pointers on how to help stranded fry I’ll be ready to take it on-board.
In my particular case there doesn’t seem to be any option as stranded means running out of water.
May be you have something on handling.
The fish I catch is done by using fry traps and walking in the ditch with a net.
The fish are put in a 5 gal. bucket,taken to the river and scooped out at roughly 4 at a time with an aquarium net so that they can be counted.
The catch process is done early morning before the sun gets going and they are no longer than an hour in the bucket .
Normal daily catch is around 200.

First, kudos to you for doing this.
Obviously if the area dewaters, whatever you do can't be worse. How many fish are in the 5 gal bucket at a time? If you can get it down to less than hour, that would help. When you release them, do it in an area they can find refuge, and add the river water gradually to the bucket to acclimatize the fish to the probably colder and more oxygenated water. Take a few minutes to do this; we used to put mesh over the top of the bucket and slowly poured in the new water; it overflows but the fish stay stay put.
The fry will be pale but will regain their normal color quickly.

 

[Birdbrain]

Good stuff, Pennel!
I use a battery powered aerator, when I transport aquarium fish. Fish consume the dissolved oxygen while they’re waiting in a container. This could be an issue, if there are many (or large) fish, and/or the water is warm. The warmer the water, the less oxygen it contains. I use this one, but I upgrade the airstone to one that‘s heavier and lasts longer:

Penn Plax Silent Air B11 Battery Operated Aquarium Air Pump For Power Outage Automatic Turn On Keeps Fish Safe: Amazon.ca: Pet Supplies

Penn Plax Silent Air B11 Battery Operated Aquarium Air Pump For Power Outage Automatic Turn On Keeps Fish Safe: Amazon.ca: Pet Supplies

www.amazon.ca