Conservation Assessment for Native Fish in the Lower Colorado River Basin

Publication Date

2013

The Gap Analysis Program is a national program with the mission to develop key datasets to conduct coarse–filter assessments for the conservation of biological diversity within terrestrial and aquatic ecosystems. The program has progressed from assessments based on political boundaries to biologically based ecosystem and watershed assessments. While many conservation programs focus on species categorized as endangered, threatened, or of concern, this program focuses on designating conservation priorities to “keep common species common”. The intent is to provide scientifically-sound information to protect species before their populations/distribution reach a level where substantial funds must be allocated for their persistence. A critical first step to slowing the loss of biodiversity is identifying gaps in existing efforts to conserve freshwater biodiversity across the landscape and then prioritizing opportunities to fill those gaps. This is the overall goal of the USGS National Gap Analysis Program. On a world–wide scale, freshwater ecosystems are facing a biodiversity crisis. The primary goal of the Lower Colorado River Basin Aquatic Gap Analysis Project was to identify riverine fish species that were inadequately represented (ie., gaps) within the existing network of protected lands in the Lower Colorado River Basin (LCRB). This basin encompasses over 200,000 kilometers of streams within the States of Arizona, California, New Mexico, Nevada, and Utah with 24 percent of that stream length managed to conserve biodiversity. Datasets were compiled to assess the spatial distribution of fish species within protected lands and locate areas that could provide a more complete network for conserving biodiversity. The datasets grouped into four primary categories: land stewardship and management, biological, environmental, and ecological threats. Land stewardship and management provided information regarding the extent of stream length receiving runoff from lands managed (at the state or federal level) for the protection of habitat and species. Biological data for native and non-native fishes were compiled from various sources, error checked prior to use, and subjected to professional review by regional fisheries biologists. Environmental and threat variables were selected based on professionally-reviewed documentation of their importance in determining population persistence of southwestern United States fishes. Data were summarized across a hierarchy of spatial scales (ie., stream segment up to major watershed). These four categories of data were subsequently used to: 1) develop an anthropogenic threat index, 2) build predicted species distribution models, 3) derive conservation values by catchments (area of land whose runoff would end up in an individual stream segment), and 4) identify species that are under-represented (and hence, presumed to be under-protected) within lands managed to conserve biodiversity (gap analysis).

ScienceBase WMS

• National Fish Habitat Partnership
• USGS Aquatic Gap Analysis Project
• USGS Gap Analysis Project (GAP)

Data source

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