WCT Multi-State Assessment February 10, 2003 . 



Conservation Populations - those cutthroat populations existing in a genetically unaltered condition (core 

 conservation populations with genetic analysis indicating greater than 99% purity) and/or populations having 

 unique ecological, genetic and behavioral attribute of significance that maybe genetically introgressed (See 

 Cutthroat Trout Management: A Position Paper - Genetic Considerations Associated with Cutthroat Trout 

 Management). Conservation populations may exist as isolates or networks of subpopulations. 



Meta-popiilation- infers that interbreeding between subpopulations (population mapping segments) can occur 

 within a few generations {3-15 years). Also referred to as a connected or networked population. 



Isolated Population - Some populations occupy isolated habitat fragments (isolates) and these populations exist 

 independently from connected groups of subpopulations. 



Genetic Risk - risk of initial or on-going genetic introgression (hybridization) with introduced species or 

 subspecies. 



Po^mlaiion Risk - risk of deterministic or stochastic declines in a population that could lead to a reduced 

 probability of viability for that population. Linked to temporal, population size, production 

 considerations and degree of isolation. 



Significant Disease (Pathogens) - Those diseases and the associated pathogens that have the potential to 

 cause significant detrimental influences on population health. Including but not limited to the 

 following: whirling disease, furunculosis, infectious pancreatic necrosis virus, etc. 



Competing Species - Those species that compete with cutthroat trout for food and space. Can be salmonid and 

 non-salmonid. Generally, non-natives that have been introduced within cutthroat trout habitats. 

 Certain competing species (i.e. brown trout) are predatory on cutthroat trout. Introduced rainbow 

 trout can be viewed as both a competitive and hybridizing species. 



Hybridizing Species - Those species or subspecies of trout that readily hybridize with cutthroat trout, primarily 

 introduced rainbow trout. Can also include introduced subspecies of cutthroat trout that have 

 been introduced to habitats outside of their respective historic range. It should be noted that in 

 specific portions of the WCT range native redband or rainbow trout (anadromous or resident) 

 co-evolved with WCT. At this point there is uncertainty on the degree and significance of 

 "natural" introgression between these species. For the purposes of this assessment, only 

 introgression (hybridization) between WCT and introduced salmonids will be treated as being a 

 potential influence on WCT. 



Genetic and density information will be provided for each mapping segment. Genetic, disease and population 

 risk assessments will be done for each conservation population. 



Barriers 



Since barriers to upstream fish movement (either long-term geologic, natural short-term, or anthropogenic 

 barriers) will be used to assess whether individual stream segments were likely historically occupied by WCT, 

 or for assessing risk of genetic introgression or disease to existing WCT populations, or whether existing 

 subpopulations are connected with other subpopulations, identification of their location and distinguishing 

 characters is very important. During the effort to describe the historical distribution identify those barriers that 

 represent long-term geologic features that would serve to influence historical distributions. These barrier 

 locations will be located (as points in ARCVIEW) on the population mapping segments. During current 



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