What happens to all the fish...

[auriemma]

What happens to all the fish after a hurricane like Irene? I know, total rookie question. But what does happen when the streams get really high and fast? Do they get washed down stream to the river? Do they find a calm spot and ride it out? Do other fish get washed in?

Help me get an understanding.

 

[gfen]

auriemma wrote:
Do they find a calm spot and ride it out?

What happened to you?
Did you get washed away?
Did new neighbors get washed in?
Did you find a safe, protected spot out of the wind and hunker down?

Fish will be moved around the water, but remember, these guys live here. It is their home, and they understand it innately. When water begins to get higher, they know how to take advantage of terrain to get out of the way and hunker down.

Not to say that fish don't die or get washed around the water, of course they do.. Same thing happens to people, too, but for the most part, you seek shelter and ride it out.

 

[pcray1231]

Most populations will handle it just fine.

As it comes down, there will be some incidents of fish getting isolated in side eddies which become separated from the stream, and they may die. But the number that wind up in this situation will be a small % overall. Go fish the side eddies and see if you can rescue a few. I've done it before, even resorted to bait (it was for the good of the fish!!!!!)

There will also be individual streams which experience acid spikes, however, I think that usually kills eggs, not fish, so in this case the timing isn't bad at all. The worst floods for this are usually early spring, when you get heavy rain on top of snow and frozen ground, the water is almost solely surface runoff unfiltered by soil, and the eggs are still unhatched.

There will also be changes in the structure of streams, some holes fill in, new ones are formed. Some spots get flushed of sediment, others get a dumping of sediment. Bugs especially are dependent on bottom type, so they will be effected more than fish. Some hatches may be weaker, some stronger, and in different places. So that hole that was an excellent sulfur hole this year may not be next year, but the other hole that wasn't a good sulfur hole may improve in a year or two.

In the long run, this kind of change is generally good, streams need a good scouring now and again. And I remember with the flooding associated with hurricane Ivan, a week or two later after the runoff subsided, we were left with supercharged aquifers and groundwater, which made EXCELLENT fishing in limestoner and freestoner alike. The water was ridiculously high, "blown out" by any other measure, except it was also clear.

 

[jjsjigs]

auriemma... love your avatar!!

 

[troutbert]

In very large floods, a lot of trout die.

The more natural the condition of the stream, floodplain, riparian vegetation, large woody debris, etc. the less trout will die in that stream during a flood.

The more the stream, floodplain, and riparian vegetation have been altered in the direction of making the stream a simple, straight, unobstructed ditch-like channel, the more trout will die in a flood.

 

[Chaz]

I have it on good authority that PFBC surveyed a couple of small brookies streams yesterday that I told them held trout. I don't know if more were there before the storm, but they were there after the storm. But small streams are very different from large streams and rivers. A population can be wiped out in a major flood. Small streams rise fast and drop fast and as long as the flood plain is accessible to the stream there is less chance of wiping out a population.
That said very few flood plains are intact.

 

[JackM]

While I agree that most trout survive moderate flood events, many that do survive are riddled with nightmares for weeks after the water subsides. I am given to understand it is very scary for them-- partuicularly the first time it happens. Some of them never recover, become neurotic or worse and end up in chemical dependency and depression.

 

[afishinado]

JackM wrote:
While I agree that most trout survive moderate flood events, many that do survive are riddled with nightmares for weeks after the water subsides. I am given to understand it is very scary for them-- partuicularly the first time it happens. Some of them never recover, become neurotic or worse and end up in chemical dependency and depression.

....and may up drinking bourbon from a homemade flask. :-?

 

[Fishidiot]

auri,
High water is, of course, a matter of degree. An extremely severe event in which a creek floods an entire forested flood plain can really change the structure of a stream and its fish populations. A series of these sorts of events over a few months can really have a cumulative effect. However, regular storms and high water events usually don't have much effect on fish. They'll hunker down and, when the water levels return to normal you'll find the same fish in the same spots.

 

[jdaddy]

afishinado wrote:

JackM wrote:
While I agree that most trout survive moderate flood events, many that do survive are riddled with nightmares for weeks after the water subsides. I am given to understand it is very scary for them-- partuicularly the first time it happens. Some of them never recover, become neurotic or worse and end up in chemical dependency and depression.

....and may up drinking bourbon from a homemade flask. :-?

Not sure which was funnier. Thanks for early morning chuckle.

 

[JackM]

Sorry, in trying to inject humor, I got the thread stalled. I think your question was answered, but to state it another way, trout must always seek refuge from current to avoid expending energy. They can swim and sustain effort to maintain a holding lie, but this requires nurtition and oxygen. A flood and highwater that last days can really tax weak fish and weaken stronger fish. There are many places to find refuge from current during high water, but it takes enrgy to find them, to maintain them and perhaps to just stay in them. Siltation which accompanies floods also can harm trout because they must filter water across the gills.

The important thing to realize is the stream and its inhabitants will survive. In fact, a strong storm often takes down dead wood and makes room for the more hardy individuals of the species.

 

[troutbert]

On some streams, severe floods may wipe out half the population, or more.

But they tend to rebound in a few years.

 

[wsender]

I think you'd be surprised at how resilient trout (and fish in general) are. They live in the stream, they're so very familiar with every nook and crany. It's not much different than animals in a forest during a storm.

Also, the water velocity at the bottom is significantly lower then at the top or in the main channel. Trout can just lie against the bottom, and exert very little effort, even during high water events. They'll even take less ideal feeding lies in favor of better more sheltered lies. They're pros at it. A million years of genetic magic is designed to keep that line going, high water and all.

I'm skeptical of anyone that says 'x amount of fish will die during these events'. Far too many variables to definitively make a statement like that.

 

[pete41]

troutberts right about mankind screwing up natures plans.

 

[auriemma]

jjsjigs... Thanks... its how I feel at work most of the time.

To the rest... thanks for the humor and info.

 

[jayL]

wsender wrote:
Also, the water velocity at the bottom is significantly lower then at the top or in the main channel. Trout can just lie against the bottom, and exert very little effort, even during high water events.

Yep. Watch underwater videos of trout feeding. They sit on the bottom, seemingly effortlessly in some very fast water. They only appear to expend effort when they move into the main flow to grab a meal. Big searching flies don't just work in fast water because they are easier to notice in the turbulent flows... they also work because the reward for working so hard for a meal has to be higher.

 

[Gone4Day]

Couple years ago I read a academic paper on fluid dynamics, partially funded by the defense department, where they measured the energy expenditure of swimming trout. The surprising result was as current velocity increased, trout used less energy to maintain position. Apparently in slow water, they had to work their fins and gills much harder to stay in place. As the current increased, their swimming efficiency increased as well.

The extra oxygen available from more water passing through the gills was not enough to account for the results. They went on to show the aerodynamic shape and sinusoidal body motion allowed trout to maintain position in a current while barely using its fins. Somewhat like a bird flying into the wind without flapping its wings.

 

[csoult]

It is amazing how efficient nature is.

 

[wsender]

Trout are really incredible when they're in their lies. I believe there is a video out there called "Trout Lies" or something to that affect and it's about an hour and change of great underwater footage of trout in a variety of lies. There is even footage showing that trout can move forward against current without using their tails and only manipulating their pectoral, dorsal, and anal fins. It's really quite remarkable.

Also, that video sheds a lot of light on to the whole 'adipose fin is useless' debate. It's worth the watch.

 

[mcneishm]

The stream I fish the most, the Saucon Creek, gets hammered by high water every year. Usually at least one of the events is not unlike Irene the other day. The stream gets very far out of it's banks. Trees fall; some are washed down. Pools are scoured out or filled in; new channels appear. I've never known that to have much effect on the stream. Despite the high water events and the number of people that frequent it, whether fishermen or picnickers, I've been very successful there over the years and continue to call it my "home" water.