The red
snapper, Lutjanus campechanus, is one of the most
sought-after fish in the Gulf of Mexico, prized by both commercial
and recreational fishermen. Red snapper makes excellent table
fare and is featured in many fine restaurants. Most red snappers
landed in Louisiana are caught in federal waters or beyond
three miles of shore. Other members of the snapper family
(Lutjanidae) found in the northern Gulf of Mexico
include vermillion snapper or B-liner, gray or black snapper,
lane snapper, and occasionally cubera snapper. Snappers are
often the most abundant fishes around oil platforms, shipwrecks,
and artificial reefs.
Red snappers
spawn in late spring and summer, with peaks in July and August.
It is uncertain at what depth or location red snappers spawn,
but some scientists believe that fish move away from reef
structures to spawn. Once spawned, the eggs are buoyant and
float to the surface where they hatch in about 24 hours. At
this stage the larvae are about 1/16 inch and extremely vulnerable
to predation. They grow rapidly in the warm surface waters
for about 20 days, after which time they begin to settle to
the bottom. At six months to one year, juvenile snappers begin
to migrate to reefs and become structure-oriented. Red snappers
grow about four inches per year for the first six years, then
growth slows. Average lengths per age would be eight inches
at two years, 16 inches at four years, 24 inches at six years,
and 28 inches at eight years. Since it takes three to four
years for a fish to reach a spawning size of 15 to 16 inches,
it's easy to realize how increasing size limits increases
the potential for reproduction.
The history
of red snapper management has undergone many changes by the
Gulf of Mexico Fisheries Management Council under the reef
fish management plan. Modifications to the management plan
are recommended by the council based on biological and socioeconomic
data. Any changes must be approved by the National Marine
Fisheries Service (NMFS).
The Sustainable
Fisheries Act of 1996 requires the regional councils and NMFS
to define maximum sustainable yield (MSY) and adopt new and
generally more conservative definitions of overfishing and
optimum yield. The overfising threshold for red snapper is
26% SPR and the optimum yield is 10% above that, or 36%. In
1984, the stock was estimated to be about 0.6% SPR at which
time development of a recovery program began. The forecast
is for the overfishing threshold to be attained by the year
2033. Progress toward the goal will depend on better fisheries
data, wise decision making, and compliance with regulations.
Currently,
red snapper stocks are considered to be in an overfished state.
Overfishing, in this case, means fishermen were removing fish
before they had a chance to spawn or enter the "spawning
stock." The condition of the red snapper stock is measured
as spawning potential ratio (SPR) which is a measure of the
stock's reproductive capability. Spawning potential ratio
is the number of eggs that could be reproduced by an average
recruit (mature fish) over its lifetime when the stock is
"fished," divided by the number of eggs that could
be produced by an average recruit over its lifetime when the
stock is unfished. Thus, SPR compares the spawning ability
of a stock in the fished condition to the stock's spawning
ability in the unfished condition.
EXAMPLE:
- 10
fish survive the first two years of life and are now large
enough to get caught (recruited) in the fishery.
FISHED
POPULATION:
- 4 are
caught before spawning (no eggs produced).
- 3
are caught after 1 spawning (some eggs produced).
- 3 live
to spawn 3 times (many eggs produced).
- During
their lifetime, the 10 fish produced 1 million eggs and
the average recruit produced 100,000 eggs (1 million divided
by 10).
UNFISHED
POPULATION:
- 3
die of natural causes after spawning (some eggs produced).
- 7 spawn
3 times (many eggs produced).
During
their lifetime, the 10 fish produced 5 million eggs and the
average recruit produced 500,000 eggs (5 million divided by
10).
The spawning
potential ratio (SPR) is then
