Fish diversity is tightly connected to the quality of aquatic habitats in any river or stream. To assess whether aquatic habitats are supporting desireable fish communities, we compared the species present in an area to the species that the Arizona Game and Fish Department has identified as desirable or undesirable.
How is it measured?
The Verde Watershed Fisheries Management Plan developed by the Arizona Game and Fish Department includes 82 management units. For each unit, Arizona Game and Fish maintains a list of desirable and undesirable species. Species present that are not on either of these lists (i.e., are deemed neither desirable nor undesirable) are also included. Indicator grades were calculated as the difference between the fraction of desirable species present and the fraction of all species present that were undesirable.