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FI SH A  B U NDA N C E

ORITY ON

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RI

RE

TH

EF

S FOR HEAL

What Is It?

BENCHMARK

Fish abundance is a count of the number of fish in a

No decrease from current MAR-wide

given area. Fish abundance data can be presented

averages for total fish biomass (~4600

in terms of total fish abundance or in terms of

g/100m2 ) or commercial fish biomass

g/100m

the abundance of key species or guilds. Size is an

(~1100

(~1100 g/100m2).

).

important ancillary measurement, as abundance and

size together can be used to calculate fish biomass.

TA R G E T

Two useful indicators for the MAR ecoregion are:

At

At least a 20% increase in total

fish biomass (to ~5520 g/100m2

(1) Total fish biomass, and

MAR-wide average) and commercial

species biomass (to ~1300 g/100m2).

species

(2) Commercially significant fish biomass.

Consolidation of an ecologically

For more information about parrotfish biomass, see

representative, well-managed, regional

indicator F11 ­ Herbivorous Fish Abundance.

MPA network.

Why Do We Measure It?

RED FL AG

MAR-wide fish biomass averages (for

Total fish biomass is indicative of trophic structure and

all habitats) that fall below ~ 4100

overall reproductive output. Commercially significant

fish biomass can be used as an indication of overall

g/100m2 total fish biomass or 1000

g/100m

status of fish stocks, fishing pressure, habitat

g/100m2 for commercial species.

g/100m

conditions and recruitment success.

Fish populations are characterized in order to

(no depleted functional groups), which are integral to

understand changes in community dynamics and to

the functioning of coral reefs.

help identify human impacts, such as overfishing and

How

How Do We Measure It?

habitat destruction. Intense fishing directly affects

fish populations by eliminating organisms (especially

The AGRRA protocol (which is also used in the MBRS

large-sized individuals), reducing spawning potential

protocol) calls for a diver to swim along 10 belt

and decreasing larval recruitment.

transects (2 meters wide and 50 meters long) at each

"Healthy" reefs should have intact fish assemblages

site, estimating the number and size ranges of certain

fish species16,17. Surveys count  key fish species

that (a) play an important role in reef ecology (e.g.,

herbivore, carnivore), (b) are commercially important

(e.g., all snappers and groupers), or (c) are likely to be

affected by human impacts (e.g. commercial species,

and those species that depend on mangroves, like

the rainbow parrotfish). Fish size and density (number

of fish per unit area) are measured for thirteen key

families and species. (See Appendix 3 for a list of the

thirteen key families and species.)

Usefulness

Usefulne s s

Tracking the abundance of fish assemblages on the

reef is a core element of any monitoring program. Fish

surveys must be carefully planned. Fish biomass can

vary with habitat characteristics, depth, recruitment,

and fishing pressure. Many commercial species have

Shalini Cawich / WWF

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