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The
Queen Conch, known locally as the Broad Leaf Conch, is essentially
a large, vegetarian, marine snail native to the western Atlantic Ocean.
Demand for its delicious meat and beautiful shell have contributed to
chronic over fishing and placed it under enormous stress throughout the
Caribbean.
The Queen Conch is the second largest of the five Caribbean species of
Strombus conch, capable of growing to an average adult length of 8-10
inches. From birth, it creates a hard shell to protect its soft body
by excreting calcium carbonate - a compound present in many animals such
as the skeletons of coral polyps as well as our own bones and teeth.
The mantle, a layer of skin surrounding the foot and lining the shell
wall, discharges the calcium carbonate as a liquid which then hardens
to form the shell. Conchs grow their shells in a clockwise spiral until
a lip begins to form.
As the conch matures, it grows a fragile, flared lip that forms the base
of the shell. This helps to prevent the conch from being overturned by
wave action during rough weather. Once the lip forms, the shell ceases
most of its growth in length and begins to gradually thicken as the conch
ages. The development of the lip means that the conch is now, basically,
fully grown, however it is not yet sexually mature.
Sexual maturity comes
at about 3 - 4 years of age. At this point,
it will have reached a length of approximately 8 inches. Breeding and
spawning activity is most prevalent during the warmest months with
some activity occurring year-round in warmer climes.
Conchs mate 'front to back' with the male positioning himself
behind the female with his shell touching the back of hers, gripping
her shell lip with his foot. He extends his spade-like verge and deposits
sperm into the female. This new supply will be stored for future fertilisation
at her next spawning.
Females like current-swept, sandy or gravel bottoms upon which to lay
their eggs. During spawning the eggs are coiled inside a continuous,
clear tube which is camouflaged by grains of sand attached to its sticky
surface.
The egg mass is capable of containing about 300,000 to 500,000 eggs.
Each female can lay around six egg masses during any one spawning season.
It is important to note that spawning females should remain undisturbed
during this vital reproductive act.
In approximately 3 - 5 days, at temperatures ranging from 75 - 84°F.,
baby conch, called velligers, hatch out and immediately start swimming
up toward the surface. The tiny, pin-head sized velligers are born
with minute shells called protoconchs. They will become temporary members
of the vast community of marine life called plankton that drift and
float
in the oceanic currents. While many marine organisms remain as plankton
for their entire lives, conchs simply use this stage to help disperse
their young to new areas. Conch velligers feed on microscopic, drifting
plants and are, in turn, eaten by a myriad of predators. Astoundingly,
it is estimated that perhaps less than one per cent of hatchlings will
survive their sojourn as plankton.
After about three weeks, the surviving velligers drop out of the water
column and settle into the sandy ocean floor. Here they undergo a major
physical transformation, taking on a miniature adult-like form. During
their first year, Queen Conchs bury in sand or hide beneath debris
during daylight hours, emerging only at night to feed. By the end of
this year,
conchs will have grown to about 3 inches in length. Availability of
nutritious plant foods and warm water temperatures are crucial in determining
how
fast conchs grow. Their average life span is predicted to be six to
seven years.
The drastic decline in conch populations across the Caribbean due to
over-fishing, led to it being placed on the Convention on International
Trade in Endangered Species' (CITES) list in 1992. This means that
member nations are obliged to have a fisheries management plan in place
in order to export Queen Conchs. Nevertheless, conch populations remain
in an extremely fragile condition. One estimate suggests that out of
400,000 offspring, fewer than one conch will survive into adulthood.
This alarming statistic, coupled with other environmental and human
pressures, signals a worrying time for the Queen Conch. The Cayman
Islands' Department
of Environment conducts an annual conch survey to monitor the success
of marine parks and replenishment zones in stabilising existing populations.
In addition, they continue to recommend a reduction in legal catch
limits to supplement their efforts and help protect the Queen Conch
for future
generations. Conch season is closed May 1 through October 31, with a catch limit of five per person or ten per boat per day, whichever is less.
No one may purchase or receive more than five conch from Cayman waters per day. For more information see our sustainable seafood program Cayman Sea Sense
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