Bio-productivity

The total amount of living material (number of organisms or kilocalories/mile) a given area of river can produce (see: Biomass) within a prescribed period of time (usually one calendar year). Often, this measurement is in terms of a specific type of aquatic life form (e.g., macrophyte, macro invertebrate, fish).

Links
  http://www.umt.edu/biology/flbs/Research/SalmonRiversEcology.htm