FIGURE 68.—Rearing ponds of various types have been constructed.
STREAM-IMPROVEMENT Work in the National Forests to Develop Better Fishing
Possibly no work done in the national forests by the Civilian Conservation Corps and other relief agencies presents such great opportunities for immediate returns or has proved of so much interest to the general public as the work of stream improvement to develop better fishing. In the Medicine Bow National Forest of Wyoming, as well as in the many other national forests in Wyoming and Colorado where stream-improvement work has been done, it has usually been of two classes. Rearing ponds have been constructed into which fry can be placed for a year or two before being liberated in the trout streams, and improvements made in the streams to better conditions under which trout may grow and develop (fig. 68).
Conditions in mountain areas are at best severe and small fry have a slim chance of survival against their many natural enemies, including larger trout, and because of /the change from hatchery to field conditions, such as swift running water, small supplies of natural food, and handling between hatchery and stream or lake. To develop fry to fish of sufficient size to withstand most of these dangers, is the purpose of rearing ponds. These ponds have been built in localities of high altitudes where mountain lakes of glacial origin are to be kept stocked with trout and where fry are retained for but a single season, as well as at lower elevations where the fry may be left for 2 years, when they will be of sufficient size to care for themselves with little or no loss. Loss in planting fry directly into streams or lakes has been reported as high as 95 percent, while loss in small fish transplanted from rearing ponds to streams or lakes is usually almost negligible.
Various types of rearing ponds have been constructed, including earth dams with metal or wood standpipes for draining the pond, earth dams with concrete cores, and timber dams underlaid with loose rock. Some very cheap and serviceable ones have been constructed by making use of beaver dams and installing standpipes and drainage boxes at costs of but $50 to $75. The general plan is to put fry into the pond in the spring and drain the pond either during the following fall or the second fall, and transport the small fish to streams and lakes by truck or pack horse.
Improvements placed in the rapidly flowing, rock-strewn mountain streams present an opportunity to greatly increase the production of trout. The mountain streams of the West are limited in acre production of fish both by lack of food and depth of water. Improvements now being made include the construction of simple log and rock dams to form stream pools. These provide deep, quiet water and opportunity for plant life to develop, which in turn induces insect life (fig. 69). Deflectors or jetties which force the current to scour the upper portions of pools are also being built as well as brush or log covers close to the shore under which trout may avoid the direct sunlight and take refuge from kingfishers or other enemies.
So far the work is largely experimental, but it is already showing surprisingly favorable results and it is felt that in a year or two these efforts will greatly increase the fishing opportunities in a region now subject to steadily increasing use.