Fish abundance is a measure of the number or amount of a fish in a given area. Scientists usually collect both count and size data. Abundance is then presented in terms of fish biomass (total weight of fish per unit area).

These two indicators are of particular interest:
• Biomass of all (total) fish
• Biomass of commercially significant fish

 Total fish biomass gives important information about trophic structure and overall reproductive output of fish on the reef. Commercial fish biomass gives an indication of overall stock status,fishing pressure, habitat conditions,and recruitment success.

We recommend continued regular monitoring of fish abundances, along with compilation of new and historical data in an accessible database for use in meta-analyses and other studies.

Surveyors should follow established sampling methodologies that take into account species behavior and habitat preferences.9 Tracking fish assemblages is a core element of any monitoring program.

For total fish abundance,a promising sign of Benchmark reef recovery would be a MAR-wide average biomass of 5000 g/100m2. In1999-2000,regional surveys found that total fish biomass:10

• Averaged 4618 g/100m2 (about three-fourths as
  large as the Caribbean average.
• Was slightly higher on reef crests than on fore reefs

•  Averaged 1083 g/100m2 (about three-fourths as
  large as the Caribbean average)
• Was similar on fore reefs and reef crests