• Because the indicator species does not have to be a dominant 

 species in the harvest, extensive data on catch and consumption 

 patterns may not be needed. 



The disadvantages of the indicator species approach are that: 



• The exposure estimate may be biased if the indicator species 

 does not truly represent the case of interest (e.g., average- or 

 worst-case concentrations of contaminants) 



• The selected species may be a good indicator for some con- 

 taminants of concern but not for others 



• If the selected indicator species are not major components of 

 the harvest, the exposure assessment may appear unrealistic 



• Background data on the distribution, abundance, and con- 

 tamination of the harvested species are usually needed to select 

 appropriate indicator species 



• If a contamination problem is apparent, collection of samples 

 of other species and size ranges of concern may be necessary. 



Phillips (1980), Tetra Tech (1985b), and Phillips and Segar (1986) 

 provide criteria for selecting target species for bioaccumulation sur- 

 veys. Important criteria to consider when choosing indicator species 

 for an exposure assessment are listed below. The target species should 

 be: 



• Harvested by the exposed population or be representative of 

 the contamination levels in the primary harvested species 



• Representative of a specific study area (e.g., relatively seden- 

 tary or restricted from migration by the presence of physical 

 barriers such as dams or waterfalls) 



• Easy to sample and abundant enough to obtain adequate 

 samples 



• Large enough to yield an adequate sample size for chemical 

 analysis. 



Some additional criteria for target species to be used as indicators of 

 contaminant concentrations in the environment are: 



• Contaminant concentrations in the target organisms should be 

 related to those in the environment 



• Metabolic regulation of contaminant concentrations by the 

 target species should be absent or weak 



• Contaminant interactions should not greatly diminish the use- 

 fulness of the target species as a site-specific indicator when 

 contaminant composition is expected to differ among sites 



• Target species should integrate the effects of contaminant 

 uptake over time 



• Target species should have a high bioaccumulation potential 

 for the contaminants of concern, especially if a worst-case 

 scenario is desired. 



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