Pond Boss Forums STOCKING A NEW POND Creating the food chain How much loss in rain event?

We currently have 5 inches of rain on the ground with an additional 2-3" coming in the next 48 hours. The overflow pipe is handling the influx of water just fine in my 2 year old pond. I went down to the overflow this afternoon and noticed fathead minnows that had escaped the pond. My question is how much is lost during a rain event like this? I have FHM, GSH, LCS, BG, LMB stocked. I went through 1 year of bait production before stocking the predators this Spring. Is the natural tendency of fish to swim upstream and avoid heavy current downstream? We're these fish just flushed out accidentally or do they purposely head out the pipe? If so, any way to stop it? Thank you all for the valuable information!

The FHM I have observed generally try to head upstream. There will be some loss out the spillway, but usually not enough to hurt the numbers significantly. You might lose a few BG fry. As I stated in another post, I have never seen adult BG or CC go out the spillway downstream. It's more likely that any fish in downstream ponds will try to swim upstream to yours, given sufficient depth. Other than FHM, almost all migrating fish into spillways will be juveniles. Grass carp are the exception. They will try to swim downstream out of the spillway given sufficient water.

A neighbor of mine got gizzard shad in his pond a few years ago from a creek attached to the White River about a half mile away. This upset him initially, but a few months ago his son in law caught a LMB over 11 pounds. It's a 3.3 acre shallow (5 to 7ft) borrow pit.

The BG I found in my yard last year after going over the emergency overflow were all YOY. Any where from a half inch up to a couple inches. I think the smaller fish just get overcome by the current or combination of current/wind/waves and get flushed down stream.

I have stood at the outlet of my forage and sediment ponds that dump into my main pond with a tight mesh dip net over the outlet. I had to stand there several minutes to get a few fish in the net, BG and FHM. So some do go down stream but likely only the ones in close proximity to the outlet that get overcome by the current.

I would be more worried about contamination of BH and GSF coming upstream than loosing a few young fish at the outlet.

Upstream infiltration should be impossible due to the fact that the overflow pipe sends water out with a 3 foot drop to a rock bed that slows the flow down to the intermittent creek. Any fish swimming upstream would need to travel about a mile from the river into what generally is a dry or nearly dry creek. Then would need to climb the 3 ft. outflow water drop.

What about downstream infiltration?

There is a youtube video that I searched for a couple days ago to link to but could not find it.

It showed what looked like water coming out of about a 6" pipe and dropping about 3 to 5 feet to water. And sunfish of some sort swimming up the flowing stream of water to the pipe. Could not tell if any of them ever made it, but they were getting within inches of the pipe swimming up the falling stream of water.

And they were persistent about it.

Wow! Now that is determination!

John, I'm at the highest point in the watershed. My 12 acre CRP field is the only runoff coming in. I think the only possible way of getting natural introduction of unwanted fish would be eggs deposited from waterfowl and wading birds.

I don't think birds of any kind are much of a problem with unwanted stocking of fish. That's mostly legend.

So I did a short non-scientific study of organism loss coming out of discharge pipe. I spent about 20 minutes filtering the discharge through a net with approximately 1/8" mesh. I would use a stopwatch and filter in 1 min. intervals. I filtered the entire discharge for the 1 minute and dump the contents in a bucket. Here is what I found by each minute:

#1-3 toad tadpoles
#2-4 toad tadpoles
#3-4 toad tadpoles
#4-3 toad tadpoles
#5-1 toad tadpole
#6-0
#7-4 toad tadpoles
#8-5 toad tadpoles
#9-4 toad tadpoles + 1 bluegill
#10-4 toad tadpoles + 2 bluegill

All fish in the pond are fingerlings. Bluegill are 2". I also saw FHM in the discharge pools so I know they are coming through as well. The numbers lost seem to be sizable. This is out of a 8/10 acre pond.

In a flood, most fish try to go upstream. Only those close to a discharge seem to be sucked through the overflow.

I had the same situation at my pond a couple of years ago. The hole that the discharging water created a pretty good sized hole. When everything settled down, I put a trap in. I caught a bunch of small BG and GSF. Then I checked with a neighbor who had a previously barren small pond about 150 yards down from mine. We seined but found only smaller fish. If the same holds true for you, your loss should be minor.

Is it worth trying to install a screen of some sort before the discharge pipe entrance to stop any loss?

Hunter
I would hesitate putting a screen over the only water escape. Lots of floatsam in rain events that can block the water from escaping possibly causing flooding over the dam

We had 3 inches if rain over the weekend and my small pond ran out the spillway. I walked down the hill this evening to see what got out and was stranded down on the flat road. Lots of small BG in the 1-2 inch range, 4 YP in the 3-4 inch range, several small GSF which I didn't stock or want, and a few FHM, including some about 3 inches long in spawning colors. I collected the YP, the larger BG, and the large FHM and returned them to the pond. I was surprised by the YP leaving the pond but it was good to see I have hat at least some recruitment.

Pat, same concern here! I was tossing around the idea of using 1/2" square hardware cloth staked out from the discharge pipe abou 4' and extending either side of the pipe about 2'. Creating kind of a fish-free zone around the pipe but not close enough to the pipe to choke flow. If it extended no higher than the top of the pipe, it would allow water to escape over the top in case of obstruction but not high enough to force over the emergency spillway.

Poppy, glad you retrieved some of your fish! I did the same but most were headed downstream!