The Science Line: Clean Water Results in Smaller Fish

By: Jake Bussolini

In a previous issue, I wrote about my concern that the food source for the fish in Lake Norman is slowly disappearing by the noticeable absence of large schools of shad. Since that time, I have had some feedback from anglers and I have discussed the possible problem with wildlife officials. This writing is an update of my findings.

Anglers who do most of their fishing in the upper areas of the lake have reported that they do not see that problem in the areas that they fish, primarily north of the 150 bridge. There is also a general feeling that the game fish in the northern regions of the lake are larger than those caught in the southern part of the lake. I have also come to that conclusion. That naturally leads me to ask why?

In one of my books, written several years ago, I answered the question asked on a local angler. “Why are the game fish in Lake Norman smaller than those caught in other waters elsewhere in the country?” My answer then possibly relates to the shad shortage problem that I am now discussing. Lake Norman waters are very clean compared to many lakes in terms of the level of nutrients contained in the water. There is an adequate amount of food in the lake but the water quality is so high that it lacks the nutrition required by the fish to extend their growth.

Nitrogen and phosphorus are nutrients that are natural parts of the aquatic ecosystem. These two elements support the growth of algae and aquatic plants, which provide food for fish and other smaller organisms that live in the lake. Lake Norman is but one of many lakes fed by the Catawba River. The river itself, because it flows over miles of different types of land, picks up several different nutrients along the way. As the river flows into Lake Norman, if drops its high nutrient levels into the north end of the lake. Lake Norman is so large, that the current flow downstream slows to nearly neutral flow in the south part of the lake resulting in the water at the north end of the lake containing higher nutrition than the water in the southern regions. The fish, including the small bait type fish, will naturally gravitate to the higher nutrition water closer to where the river water enters the lake.

This theory makes some sense to me and we may see some change as the spring approaches since the recent water draw down and the large amount of rain will certainly cause a change in the water flow rate, even in the south areas of the lake. Anglers should keep their eyes on their sonar screens and let me know if they begin to see the shad return to the south end of the lake. Like the weather, these things are often cyclic, and hopefully those of us who normally fish the south end of the lake will see the shad return soon. My e mail is Let me know your experiences.

Jake Bussolini is a freelance writer who has written several books about freshwater fishing. His books can be seen at