Barbs and Backlashes

Fish Need Water by Nebraska Game and Parks Commission
June 18, 2009, 3:12 pm
Filed under: Fishing | Tags:

One of my sarcastic replies when asked how drought or low water levels affect fish populations is “fish need water”!  Water is the most basic habitat requirement for fish.  Nebraska is a great plains state where most of our water bodies are man-made, many of them reservoirs or impoundments of some kind.  “Life on the Great Plains” means we will have wet cycles and dry cycles.  Water levels in our reservoirs will always fluctuate and those fluctuations will have a dramatic impact on fish populations!

In recent years we have had drought conditions in Nebraska that have been as severe as any drought most of us have experienced.  How does that affect fish populations?  How many minnows could you keep alive in 5 gallons of water?  Now, how many minnows could you keep alive in 1 gallon of water?  During the duration of the recent drought we have seen water levels in some reservoirs drop that much–to 25% or even 20% of capacity!  In an environment that changes that much, fish populations have to adjust.  Less water means there will be less fish, “fish need water”.

In some cases there are fish that migrate out of reservoirs with water that is released and that is one way that those populations adjust.  They also adjust to less available habitat with increased mortality rates–more fish die.  Some of that additional mortality is the result of natural mortality and in extreme cases major fish die-offs may occur.  Ironically, the fishing usually remains quite good while water levels are declining because you have fish concentrated into a smaller area and there is less natural prey available in that reduced habitat.  Concentrations of hungry fish mean easy fishing, and with declining water levels increased fishing mortality will also reduce fish populations to the level the smaller habitat can support.  There is absolutely nothing wrong with anglers utilizing that resource and being part of that “down-sizing” process.

Fortunately, dry spells are followed by periods of more precipitation.  Many Nebraska reservoirs have recovered from their drought levels of a couple of years ago.  Again there is irony in the fact that when the water levels come back up, anglers then pay the price for the drought.  Fishing is usually good while water levels decline, but when water levels start to rise you have a down-sized population of fish that now has more available habitat to utilize.  Couple that with the fact that the bottom substrates of Nebraska reservoirs with low water levels grow lots of cottonwoods, willows, cockleburrs, smartweed and other vegetation that provides great fish habitat when it is re-flooded.  As water levels rise the fish spread throughout that extremely productive flooded habitat where they find plenty to eat and become tough to find and catch.  We are seeing this phenomenon now on some Nebraska reservoirs that had low water levels just a couple, three years ago.  Harlan County Reservoir has acres and acres of flooded vegetation right now, and fishing has been tough.  Lake McConaughy is still a long way from being full but even last year water levels recovered to the point where some of the terrestrial vegetation that sprouted during the drought was re-flooded and that has made the fishing a little tougher.

But, we will take the water!  Although water levels rising back to full pool levels may make the fishing tough right now, in the long run our reservoir fisheries will benefit from more water!  The flooded terrestrial vegetation is very productive and will produce some big year-classes of fish for the coming years.  In fact in some cases populations of  crappies or northern pike that thrive in the flooded terrestrial vegetation will experience a boom in the coming years.

Reservoirs with more stable water levels will tend to have more stable fisheries.  We have some irrigation reservoirs in Nebraska that have a consistent supply of water even during drought conditions.  Reservoirs like Merritt, Sherman, Calamus and Medicine Creek fill to full pool or near full pool every year regardless of the severity of the irrigation drawdown the previous summer.  Although water levels in those reservoirs still fluctuate on an annual basis, just the fact that they fill back to full pool every year is a luxury that benefits fish communities in those reservoirs.  In eastern Nebraska reservoirs are smaller and used more for flood control and less for irrigation.  Water levels in flood control reservoirs can also fluctuate, but typically fluctuations are much less dramatic; therefore, fish that thrive in those reservoirs and the fisheries that develop are different than those found on larger irrigation reservoirs.

Most reservoirs in Nebraska have recovered from their drought conditions of a couple years ago.  Some of the reservoirs in the Republican River basin are still below full pool and Lake McConaughy is still just over 50% of capacity.  We have a ways to go especially at McConaughy and in other waters in that system, but overall the water situation right now is a lot better than it was a couple of years ago.  Anglers can expect some tougher fishing following the recovery of water levels, but hopefully we all remember that “fish need water” and our fisheries will benefit from water levels back near full pool!  And keep praying for rain, snow, sleet, drizzle, mist, precipitation in any form!


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