Evaluating
a marine protected area with a finfish tagging program at Glover's Reef Atoll,
Belize, C.A.
Introduction
Glover's Reef is a tropical atoll, located about 45 km off the Coast of Belize
(16o 44' N, 87o 48' W). Though Glover's is isolated, over the last decade there has been increasing concern that its finfish populations (especially grouper and snapper
species) are being overfished. In response to this concern - and ongoing concerns for Glover's lobster and conch populations
- the Belize Fisheries Department, working closely with the Wildlife Conservation
Society, designated Glover's Reef a reserve
in 1993. The Fisheries Department divided Glover's Reef Reserve into
3 zones: a Wilderness zone, where no disturbances are
allowed, a Conservation zone - where no fishing is allowed (an area that includes the Wilderness zone), and a General Use
zone - where fishing is allowed. The Fisheries Department also designated a seasonally closed area on the Northeast corner
of the atoll, which was intended to protect grouper when they aggregate to spawn. There has been no consistent enforcement
of the seasonal protected area to date, and it was not until the past year (2000) that the boundary of the year-round protected
area (i.e. the Conservation zone which includes the Wilderness zone) has been marked and regularly enforced by the Government
of Belize (GOB). Now that Glover's Conservation zone is being actively enforced, it is possible to begin to assess whether or
not this designated protected area is effective in protecting Glover's finfish resources.
Project
Goals
To evaluate the effectiveness of the marine
protected area at Glover's Reef Marine Reserve, in protecting marketed
finfish species.
Project
Design
Because the finfish harvested
at Glover's move between areas, it is essential to accommodate for these movements when evaluating the effectiveness of the
protected area. By tagging fish in both the protected and unprotected areas of Glover's, we can track fish movements by seeing
how many fish tags are returned from the unprotected areas. With this information (and our own recaptures of tagged fish in the
protected area, which are again released), we can calculate an estimate of how fast fish are being caught that were originally
tagged in each area. If the protected area is effective, the rate of fishing for those fish tagged in the protected area should
be much lower than that for fish tagged in the unprotected areas. To determine this, our study requires a minimum of 1000 fish to be tagged each year for 2 years and 2 consecutive years of tag returns.
Pilot Study
With a research fellowship funded by the Wildlife
Conservation Society, T. Ihde performed a
pilot study April 2000. Study goals were to: test traditional
Belizean fish traps, establish trap rates, determine optimal depth for trapping
target species, tag marketed fish species, and to determine tag retention and
tag induced mortality. Though no grouper species were caught, snappers
were numerous and the pilot study was very successful. 80 tagged
"lane" snapper (Lutjanus synagris)
were tagged and held for 4 days. The holding study resulted in 100% tag
retention, and 0% tag-induced mortality. Fish appeared very healthy and
active with no sign of infection at the tagging site.
Status
Over the last 12 months we have
completed the first year of a 3 year finfish tagging program designed to accomplish
our goal of evaluating the marine protected area's effectiveness in protecting
Glover's exploited finfish populations. Our catch rates by species during our first study year, suggest that the recent decline of groupers in Glover's lagoon has been severe. Anecdotal reports of local Belizeans and previous work by Sedberry and
Carter (Sedberry, personal communication) indicate that young grouper were once common in the lagoon, yet we caught no grouper in 135 trap sets, made with traditional Belizean traps designed specifically to catch grouper. In spite of this, during the first year of the study, we successfully tagged more than 1,800 snapper - another common food fish seen in Belizean markets.
Tagging the
Fish
Fish are caught with traditional Belizean fish
traps 
, with dimensions: 5'x5'x3'. Traps are set in the lagoon of
Glover's at depths between 20 - 70 feet and sets last for 1
or 2 nights. Traps are hauled up slowly, to avoid pressure stress
on the animals. Once at the surface, the trap is positioned to ensure the
fish remain in the water; the trap door is opened, and 1-5 fish
are carefully
netted out 
and placed in a bucket of fresh seawater.
Individual fish are removed from the seawater and total length is quickly
measured to the
nearest millimeter 
.
Scales
are removed 
from the tagging site with an alcohol-disinfected tag applicator
(a large-bore stainless steel needle), and the
tag
is inserted 
and locked between pterygiophores (vertical bones leading up to
the dorsal fin) in the "shoulder" of the fish. The point of tag insertion
is disinfected
with Betadine 
, and the fish is then released.
To view the following two
videos you will need Quicktime Plugin, Quicktime MoviePlayer, or a similar movie
viewer. You can download Quicktime here.
Please
Note: after viewing video clip, use your browsers "back" button to
return to this page.
A video of the entire tagging procedure can
be viewed here 
, complete with annoying wind noises.
Another
fish being tagged and released can be viewed here
.
Glover's Reef Marine
Research Station - GRMR
Funding for this project was provided
by the Wildlife Conservation Society (WCS) and the
Virginia Institute of Marine Science (VIMS).
Questions, or problems with this page? please
Email Tom Ihde at: tihde@vims.edu
Back to
homepage for T. Ihde