7065 - Laserfiche WebLink

Home Browse Search

PREFACE Endangered species often generate controversies, raise emotions, and polarize opinions when the preser- vation of endangered species conflicts with economic development. This is particularly true for the endan- gered fish species of the Colorado River basin. The water of the Colorado River is in urgent demand for agriculture and energy production. The greatest known concentrations of oil shale and enormous coal deposits occur within the basin. Three species of fish, the Colorado River squawfish, the bonytail chub, and the humpback chub, are now listed as endangered under the federal Endangered Species Act. One additional spe- cies, the razorback sucker, has been proposed for listing. The Colorado state list of endangered and threatened species includes the four above fishes plus the Colorado River cutthroat trout. It is often asked: of what good are endangered species? How can they be beneficial to man =- especially fishes such as the squawfish, the bonytail and humpback chubs, and the razorback sucker, species of the minnow and sucker families that have so long been categorized as "rough" or "trash" fish that should be controlled or eliminated for the benefit of game fish? There are no simple answers to these questions. There are standard responses concerning the need to maintain species diversity in nature and diverse popu- lations within a species and thus provide the raw ma- terial for evolution. It is true that the effects on many animal species from such chemical pollutants as DDT, PCB, mercury, and Kepone provided an early warning system to the dangers these chemicals hold for man. As such, endangered species may act as an indicator or barometer of environmental influences of potential harm to man. To many, the responsibility of preventing extinction as a result of man's influence is consi- dered a duty of man's stewardship of the earth, and more practical reasons are not necessary. When Congress passed the Endangered Species Act of 1973, it was in response to demands by the American people that the accelerated trend toward species extinc- tion be reversed. It often is argued that extinction of species is a natural consequence of evolution and that man should not interfere with this natural pro- cess by preserving ill-adapted species that nature intends to get rid of. After all, the argument goes, dinosaurs, pterodactyls, and sabertooth tigers are no longer here. Who misses them? What must be recog- nized is the difference between slow natural rates of extinction (balanced with the slow evolution of new species) and a highly accelerated rate caused by man's modifications of the earth's environments. During the past century, as the human population has increased in geometric proportions and with the rise of modern technology, the human species has claimed an ever greater portion of the earth and its resources. Man has dramatically changed the original environments on an enormous scale to provide food, energy, and the amenities of life to an ever-expanding population. The creation of urban centers for living and business, the conversion of vast land areas to agricultural production (which in turn demands irri- gation and dams and chemical treatment), and pollution of soil, air, and water are all aspects of the popu- lation increase of the human species that result in harmful effects to other species. It must also be recognized that the accelerated extinction rate caused by man differs from much of natural extinction in that the extinction of a species caused by man's influence "dead-ends" an evolutionary line. Most extinct species in the fossil record are "extinct" only because of slow, gradual change in the evolutionary line. That is, continual evolutionary change led to the creation of new species. The germ plasm or hereditary material has been continuous through time, but gradually changed from an ancestral species into its descendant species. For example, the direct ancestor of man a million years ago or more is considered to be a different species from modern man, Homo sapiens. If man's ancestral species had become extinct by a dead-end type of extinction, rather than a gradual evolutionary change, we would not be here. This distinction between the two types of extinction -- a dead-ending of an evolutionary line, as contrasted to the transformation of one species into another by evolutionary change -- is critical for the continued maintenance of the diver- sity of life. The purpose of this bulletin is to provide basic information on the endangered and threatened fishes of the upper Colorado River basin, the reasons for their present condition, and what is being done and what might be done to enhance their chances for survival. The federal Endangered Species Act is examined and interpreted to explain where potential conflicts may arise due to the occurrence of an endangered species. It is hoped that this bulletin will stimulate interest and appreciation of some of the unique and 3