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Explanations for Some 'Fishy Questions'

Posted Jul. 1, 2005

As you might expect, a lot of questions regarding fishing are generated during the summer. Like me, many folks are itching to get outside and enjoy summertime activities such as those involving a rod and reel in hand. This often brings up a lot of questions about the favorite "fishing hole" based on the presence or absence of fish on the stringer.

The following are examples of some of those questions, followed by explanations.

Question: How can I keep those blue herons from bringing fish eggs to my pond on their feet? I caught a fish in my pond this year that was not supposed to be there.
Explanation: Blue herons are not responsible for bringing fish eggs to ponds. New fish species are usually introduced in ponds when small fish swim up or down the watershed during overflow events. This can be minimized by having only one pond in the watershed or having a man-made or natural vertical drop in the watershed inhibiting the fish from entering the pond from below. Another frequent cause of unwanted fish is from people stocking fish in a pond, thinking they are doing the pond owner a favor. It's a good practice to try to prevent people from stocking fish, including bait, in your pond without your permission.

Question: I have had largemouth bass, bluegill and channel catfish in my pond for more than 15 years. Now I can't seem to catch any catfish. What's the problem?
Explanation: If channel catfish are stocked in a pond with abundant largemouth bass, channel catfish recruitment will be very low to non-existent because largemouth bass consume most, if not all, of the channel catfish fry and fingerlings each year. Over time, catfish may disappear due to natural mortality and harvest. Most channel catfish generally do not live past 10 to 15 years. In ponds stocked with largemouth bass, channel catfish will need to be restocked periodically to maintain a good-quality channel catfish fishery. Be sure that the newly stocked channel catfish are larger than 7 inches so existing adult bass will not consume them.

Question: The vegetation in my pond is reducing fishing access. How can I get rid of the vegetation?
Explanation: This question is difficult to answer without learning more about the pond and identifying the species of plant(s) causing the problem. The presence of some aquatic vegetation in a pond can provide habitat for fish and help maintain good water quality. Obviously, there is a limiting threshold for fishing access, but that threshold is often subjective among those doing the fishing. Variables that can confound the issue include goals for the pond, aquatic plant species, plant abundance, pond surface area, depth of water, water temperature, local regulations and water quality parameters. Some species of aquatic vegetation cause more problems than others. Therefore, proper identification is vital to implementing techniques for successful control. Vegetation can be a problem in shallow ponds with clear water. Some control options are more costly than others.

Question: When I went down to the pond to go fishing this afternoon, I found a lot of my fish dead along the shoreline. What happened?
Explanation: Fish kills usually occur when the water is warm and phytoplankton or aquatic vegetation is most abundant and there is little wind. Fish kills in these conditions are usually caused by low dissolved oxygen in the water and usually occur during the early morning (pre-daylight) hours. This is because phytoplankton and aquatic vegetation produce oxygen during the daylight hours through the process of photosynthesis, but, at night, these same plants use oxygen through the process of respiration. The amount of oxygen used at night by plants is directly proportional to the amount of plant biomass in the pond. As a result, there is usually enough dissolved oxygen for fish during the day, but, at night, especially during the early morning hours, dissolved oxygen content can become too low for fish due to plant respiration, especially if there is no wind to add oxygen to the water through agitation. One way to combat this problem is through aeration. Unfortunately, most ponds are located in remote locations away from power sources, making aeration difficult.

Hopefully, you won't encounter many problems in your pond. If you do, however, give the Noble Research Institute a call at (580) 224-6500 and maybe we can help.