Super Cool

You might assume that the two adjectives in the title of this post refer to the groovy guy that I am.  But most of you know that ain’t true, dork would likely be closer to the truth, and all of you know I blog about fish most of the time.  This post is going to be no exception.

You might also assume that this mild winter we have been having would be good for our fish.  Winter is the hard time for most wild creatures and in some ways the worse the winter the harder it can be on the fish.  But that is not always true.  In fact, for some species of fish, this “mild” winter may actually be worse.  How in the world can that be?  Well, keep in mind that with the relatively mild weather we have not had the “normal” ice cover on many bodies.  When a body of water freezes over the cap of ice actually stabilizes conditions.  With open water through much of the winter, the water in lakes, reservoirs, pits and ponds is free to continue to mix every time the wind blows, and Lord knows the wind blows in this state!  So, when we have a winter in which the water stays open late into the winter, the water in lakes, reservoirs, pits and ponds may actually be mixed and cooled to a greater degree than if we had an early freeze that then persisted all winter.  Thus, if you wish, you could say the water becomes “super cooled” during winters when we have a late freeze up or as this winter has been in much of Nebraska, little or no freeze up.

We have some species of fish in Nebraska that are very much cold-sensitive; species that are near the edge of their range or warm-water species that just do not tolerate cold water temperatures as well as cool-water or cold-water species of fish.  For example, gizzard shad are a species of bait fish common in many Nebraska reservoirs and gizzard shad are very much cold sensitive.  Many gizzard shad die from the cold every winter, and in fact the “ideal” shad population in most Nebraska reservoirs would be one where most of the shad perish every winter leaving just a few shad to reproduce the next spring.  Under those conditions, the few surviving shad tend to produce an exceptionally large year class the following spring and the high abundance of young-of-the-year (YOY) gizzard shad results in an abundance of relatively slow growing shad that remain small enough to be available for a variety of predator fish to eat throughout the summer and fall.  Ideally, then most of those small YOY shad perish the next winter and the cycle repeats itself.  On some bodies of water, we have documented winters where there was a late freeze coupled with high winds that resulted in exceptional winter mortality of gizzard shad.

On the other hand, we have documented winters, and they were not necessarily mild winters, where there was less mortality of gizzard shad.  With less winter mortality there are more large shad in a population, shad that become too large for all but the largest predator fish to eat, and production of YOY shad tends to be suppressed in populations that already have an abundance of adult shad.

Let me give you an example of this super-cooling :  Years ago gizzard shad were the primary prey in Lake McConaughy.  McConaughy is so large and wind-swept that it seldom completely freezes over and in the worst winters super-cooling would eliminate almost all gizzard shad from Lake McConaughy.  When that happened there would be a lot of skinny, hungry predator fish swimming around in McConaughy, and the largest of those predators, striped bass, got blamed for eating all the other fish, especially rainbow trout.  The striped bass became the scapegoat for what was really a problem with the prey base in Lake McConaughy, and the result was a ban on all striped bass stocking in Nebraska waters–a moratorium that exists to this day.  The real solution to the problem at McConaughy was diversification of the prey base and a variety of species of prey fish were stocked into McConaughy.  Alewives were one of the species that were stocked and they successfully became established in McConaughy.  Now, alewives are also cold-sensitive, but with a greater diversity of prey fish in McConaughy, that fishery has been much more stable and continues to produce excellent fishing for several species of predator fish.

As I continue to ramble, let me mention a couple of other things about this “super cooling” that are important to anglers.  First of all, besides gizzard shad and alewives, there are other species of fish in Nebraska waters that are sensitive to cold temperatures.  White perch are also cold sensitive; hopefully we will see a lot of those stinkin’ buggers killed this winter.  Redear sunfish are a species of sunfish native to waters east and south of Nebraska.  Redears have been stocked into some Nebraska waters, but they tend to disappear from waters where they do not have some refuge from the coldest water in the winter.  Redear sunfish tend to do best in Nebraska waters where there is some groundwater flow or stream flow that provides some winter refuge for them.  I suspect that on Nebraska waters where redears have little or no refuge from the coldest water, there might be higher winter mortality this winter.  Bluegills and even largemouth bass are also warm-water species that can suffer some over-winter mortality; again, that might be worse this winter on waters that have been left exposed to “super cooling”.

On waters where shad, alewife, and perhaps white perch populations take a big hit this winter, the fishing might be exceptional next spring into early summer.  If the populations of baitfish are less than they usually are, then predator fish will have to search more for prey and they will be hungry more of the time.  When that happens those predator fish are much more vulnerable to anglers.  So, yes, I have been grumpy about not being able to ice fish as much as I would like this winter, but the “pay off” may come in the form of better than average fishing later this year.

Another thing I have noticed, and I have talked with other hard core “ice sticks” who have noted this same thing:  If we do eventually get some more cold weather this winter and things freeze up so we can get on the ice again, I would predict that the fishing on that “re-freeze” might be tough.  Remember that ice cover stabilizes conditions below the ice.  With all the mild weather, wind, and open water we have had this winter, it may take a while to stabilize conditions under the ice, if it ever freezes over again.  In my experience, and we have had winter ice conditions like this before, the fishing is really tough after it freezes, completely thaws, and then re-freezes.  If we get safe ice again this winter, the fishing might not get hot until at least a couple of weeks after the re-freeze and maybe not even until we get towards late ice, shortly before it breaks up next spring.

Another favorite saying of mine is “every year is different”.  Conditions are always changing and the fish we love to catch are always reacting to those changing conditions.  It can be hard to stay on top of it all, but the best anglers are always adapting and adjusting.  Some times we just have to go along for the ride and see what happens, but having some hunches about conditions and what might happen can sure make catching fish easier; at least until it all changes again.

No, neither one of those guys are me. However, I do believe they are "super cool". Ha.