There is a noticeable habitat change due to several causes, such as ranching, irrigation, urban development, and a general minor change in climatic conditions. Many variations are in direct relation, such as improper grazing, unscreened irrigation diversions, dams, and sewage disposal, to mention a few. There is an indication of a long-term warming of the general Southwest, and though this change is fractional, it does have a basic effect on habitat.
The effect of habitat change can be noted in the life of the cutthroat trout. Early records reveal that this trout, liking cool clear water, was once caught in the Rio Grande in the lower part of the box canyon north of Peñablanca. It was also caught near the town of Pecos. The fish can no longer survive in the changed water conditions and is found now only in the headwaters. Even the catfish has difficulty surviving in some sections of the rivers for lack of water. In the lower Pecos, the catfish finds difficulty in reproducing because of the high salt content of the river water.
As has already been noted, the fish that are recognized as game fish today were in short supply a hundred years ago. It was not until the railroads entered New Mexico that fish were imported to supplement the native supply. In an unpublished report by the author, it was pointed out that almost every kind of fish propagated in the United States has been imported and stocked in waters of New Mexico. Of these, some have survived beyond expectations and others have disappeared entirely.
When the railroads entered New Mexico, there were already requests for fish in the hands of the United States Fish Commission. Fish were delivered in especially designed fish-distribution cars and the consignee met the cars at designated rail sidings. From the distribution cars, the fish were further transported by wagons in water containers of various descriptions, usually wooden barrels or watertight wooden boxes, to streams or lakes as assigned. Because of the mode of travel at the time, the quantities of fish so stocked were limited, but they did provide seed stock from which their population could grow. Fish were packed on back and on horses into relatively inaccessible areas. The procedures and techniques of fish transportation have evolved to the present highly specialized equipment and methods of operation.
It is interesting to note that the quantities of fish imported and planted increased in relation to the improved transportation. The early records indicate the numbers in the hundreds and in just a few locations; later plantings increased both in numbers stocked and in waters stocked. The first fish imported to supplement the native fish was the German carp. In fact, this was the only fish imported for eight consecutive years, 1883-1890. These early plantings were followed by catfish, German brown trout, brook trout, yellow perch, largemouth black bass, crappie, rock bass, tench, rainbow trout, strawberry bass, black spotted trout, bream, smallmouth bass, salmon, white bass, and walleyed pike.
All the fish imported are classed as game fish except carp and tench (the latter did not survive). The various species met their habitat requirements, and although there were no survivals in some locations, they did acclimate in others and have developed into a substantial fishery. Some species are predominant while others, like the rock bass, are remnant and taken only occasionally. The fish most sought now and predominant in the fishery are rainbow ([fig. 2]) and brown trout, catfish, largemouth bass, crappie, and walleyed pike.
Figure 2. Joy of the fisherman, rainbow trout
Management of the fishery has progressed with technical development. When fish were planted in early years, very little thought was given about the habitat except that it was water. There was little known of the requirements of fish. As a result, fish were placed in waters only to perish. To maintain a fish population now, all techniques available are employed and fish are stocked where water and species are compatible.
Water in the desert is always at a premium for the inhabitants. The early Indian cultures used water for irrigation, and there are still vestiges of canals used by Indians to convey water to their crops. The use of water by the Indians then had little or no effect on fish life, but as irrigation development increased, a new habitat was formed. The once free-flowing rivers became dry in places, and new waters were developed in the drainage ditches in the Rio Grande Valley. The competition for water is very keen and fish and wildlife uses come after domestic, commercial, and irrigation purposes.