Following is part of a demonstration given to 8 - 14 year old at the Conservation Day Forest Resource Education Center, Jackson NJ, head waters of the Toms River
What is Trout Water?
A word we hear often is "Pollution" but this has several meaning depending on your view. As Trout Unlimited is the champion of Cold Water Conservation, and takes stream protection for trout as key, I felt that a discussion on what makes good water for trout would fit right in the Conservation Day theme.
Many believe that crystal clear streams are ideal in nature even though the stream has no aquatic life. Thus the argument for clean lifeless streams does not work for natural streams. You hear that pollution in the waters is bad. However, pollution is hard to define or even understand. I would say that there are two types of pollution, that which changes the stream bed, like silt from rain run off and trash. The second is that which changes the chemical make up of the water. One major source of chemical pollution is mining or construction trash which may contain acid or arsenic or other heavy metals like mercury. Oil based products are also bad. These kill the plants and insect which are the food sources for the trout and also some chemicals will kill fish, snakes and frogs that make the streams and lakes their home. Like too much ice cream can cause a belly ache, too much fertilizer from lawns and farms can also give the streams and lakes a belly ache.
But let's talk about what is Trout clean water and how it differs from clean drinking water. Trout Clean water must have oxygen created by moving over stones and branches, be more Alkaline than Acid and a lot of nutrients like phosphorus, nitrogen and plankton. These help plants grow in the stream or lake which is the home of insects and small minnow fishes. When the water looks clear that indicates it is short of plankton and nutrients. The darker tea color is due to rain running off the land but does not have more food for the fish. What I want to talk is how the word "Clean" can mean good or bad for trout food and the trout. The word Clean would be used to describe the water from the tap or the water here in the Toms River, but none of us would confuse the river water as drinking water. In the wild, the stream provides the food and comfort for the trout in several ways.
The Toms River is a stocked trout stream and stocked trout can live here year around. Water temp is a high of 68 degrees in summer and a low of 35 degrees in the winter and insects and small minnows are available for food. A few years ago the Tom River Chapter of Trout Unlimited chapter (Now Out Of Business) was able to hatch eggs inside a plastic crate duplicating the hatchery environment with larger river rocks over the eggs. The reason that trout can not grow in the Toms River from eggs naturally laid by the fish to adult is not the water, but the fine gravel on the bottom. The fine gravel being moved by the stream pressure covers up the eggs and oxygen is cut off and the eggs die.
The Caddis and other insect are also sort of a biological litmus paper: biologists, hydrologists, and environmental scientists all inventory aquatic invertebrates (insects, mollusks, worms, and crustaceans) to measure stream health. In the case of producing the trout and trout food - oils from cars are bad as it affects the oxygen available and kills the insects. On the other hand, leaves decaying and a dead animal in streams is good as they becomes the main food for the insect larva in the stream bed, and thus becoming food for the trout. Most of us have some idea of what insect's trout feed on, which in this river (this was given at the headwaters of the Toms River) is the Caddis, Mayfly, or Stonefly. And Fly Fishing anglers use imitations of these insects to fool the trout. Just like bait fisherman use worms. If the stream has good nutrients the insects in the stream will grow.
Will use the Caddis fly to demonstrate how the need for nutrients works. The Caddis is shaped like a moth and has four life stages that take about a year. The cycle starts with adult diving into the water, eggs being deposited on surface where the eggs sink to the bottom and stick to rocks or other things. Two weeks and then on to the next stage, called the Larva.
The Larva looks like a grub, live on the bottom and feed on dead plants and dead animals. For trout, the larva is not a big part of their meal plan as they are hard to find and eat. The Larva does not swim but sometimes bounces along from the water flow. Again the larva is dependent on having trout clean water (phosphorus and nitrogen and plankton) for its food. Then after a year, the Larva moves to the Pupa stage to hatch. Now during this short period as they move from the bottom to the surface they become food for the trout. Again if the water is too clean the Pupa never grows and the trout well - you know- do not either. Fly Fishing anglers use pupa imitation to fool the fish at this time.
Next will discuss a 1977 study that found when an upgrade to a sewage processing plant how the improvements caused a reduction in the trout in the river. Stay tuned.