WSP10862 - Laserfiche WebLink

Home Browse Search

,":l ,.:::; -, en en DRAFT AND PRECISIONAL DOCUMENT - FOR COORDINATION COMMmEE REVIEW ONLY Within the IS-year planning horizon encompassed by the Program, this Plan will provide for the formulation of annual work plans for the satisfaction of identified information needs, the timely evaluation of the success of actions implemented to protect and recover the fish fauna of the Basin, and the short term, intermediate, and ultimate actions necessary to attain recovery and allow for compatible development of the Basin's resources, 2.0. LONG RANGE PLAN Understanding the functional relationships of the San Juan River fish community and the biotic and abiotic components of the San Juan River basin is essential to the recovery of the endangered fish species, Narrowly focusing on only the two endangered species will omit important components on which the recovery of those species may depend. Therefore, a broadly based fish community approach is essential to achieving the goals of the San Juan River Recovery Implementation Program, The following provides an overview of the philosophy and approach that will be taken to achieve the San Juan River Recovery Implementation Program goals, In addition, the relative achievement of these goals will be the criteria upon which success of the Program as a whole will be judged and evaluated, 2.1. BACKGROUND The native fish community of the San Juan River evolved in a system characterized by dramatic physical environmental changes, Flow varied from almost non-existent to devastating floods, Seasonal and annual environmental changes wrought by widely different flows were not predictable, but over time such variations were certain to occur, Such extremes in abiotic conditions presented aquatic organisms with environmental conditions that changed frequently in availability, quality, and extent. Within the naturally variable system, species evolved strategies to utilize the differentially available habitats and avoid competition for such, The selective pressures of harsh environments contributed to low species richPless and diversity of lhe San Juan River. Although few in number, most native fish species are long-lived, Different life stages (i,e" larva, juvenile, sub-adult, and adult) differentially utilize available resources and thus function as distinct ecological species. Despite a level of niche segregation, the ecological species are interdependent. A surficially simple system belies a complex one of many subtle biotic and abiotic interactions and dependencies, The imperilment of the native fish community and extirpation of several native species were caused by a variety of human-induced biotic and abiotic modifications of the San Juan River ecosystem, Dams and diversion structures fragmented ranges, disrupted natural thermal and flow regimes, altered sediment transport dynamics, and diminished availability of seasonally required habitats; agriculture, industry, mineral extraction, and urban development diminished water quantity and quality; artificial channel structuring eliminated important habitats; establishment and encroachment of non-native riparian plant species reduced the naturally varying river channel; watershed management practices, exacerbated by natural climatic change, elevated sediment loading of the river; and introduction and establishment of over 20 non-native fish species and management of non-native sports fishes (including native fish eradication) imposed additional competitive and predaceous pressures. The strategies native fishes evolved to survive in a naturally variable and harsh environment ill-prepared them for persistence in an 3