Most exploited sea cucumbers have separate sexes. Some species,
like the sandfi sh, are relatively fast growing and reach reproductive
size within a year or more but take another two years to reach an
acceptable market size. Other species grow more slowly and live
between 5 to 15 years.
Many tropical species reproduce at the start of the warmer months. A
few species, such as the black teatfi sh, spawn during the cooler months.
During spawning, females (~) release eggs into the water and these
are fertilised by sperm released by males (|). Successful reproduction
depends on large numbers of sea cucumbers being in the same place.
Fertilised eggs hatch and develop through very small forms (larval
stages) that drift with ocean currents for several weeks; less than one
in every thousand of these survives to settle on the sea fl oor as a young
(juvenile) sea cucumber.
Sea cucumbers do not move very far from the areas in which they
settle and less than one in every hundred juveniles survives to
become an adult.
Fishing methods
Sea cucumbers are usually collected by hand at low tide or by free
diving. Underwater breathing apparatus, which has also been used, is now
illegal in many countries as its use has severely reduced many populations.
In some Pacifi c Islands the guts and reproductive organs, sometimes
partially fermented in seawater, are consumed. A slit is made in the
body wall of species such as the curryfi sh, Stichopus herrmanni, and the
internal organs are removed; the sea cucumber is then returned to the
sea where it is believed to regenerate its internal organs.
Minimum size limits have been applied by many
fi shery authorities. As sea cucumbers shrink
during processing, minimum sizes are usually
given for both live sea cucumbers and the dried
product. Minimum sizes for various species are
given in the sea cucumber identifi cation cards
available from SPC.
In some areas, national authorities have declared
a moratorium (during which fi shing is prohibited)
to allow sea cucumber populations to recover.
Others have banned the export of particular
species.
In addition to supporting national regulations,
communities could take the following actions:
ban the use of underwater breathing
apparatus for collecting sea cucumbers in
local fi shing areas, which has caused the
loss of many sea cucumber populations;
place a ban (or tabu) on collecting sea
cucumbers, which may be necessary if
stocks have been severely depleted. Bans
would have to be in place for several years
to allow time for stocks to recover and for
adults to breed;
establish rotational harvesting in which
diff erent areas are fi shed in rotation. If the
community fi shing area is large enough, it
could be divided into four or fi ve smaller
areas. Sea cucumber collecting could be
allowed in a single area during 1 year and
then allowed in the other areas in turn
during the following years. A large number
of smaller areas are required because
populations of sea cucumbers increase
relatively slowly;
establish small, community-managed
marine reserves or no-take areas. As
sea cucumbers do not move much, these
reserves could be relatively small (between
0.5 and 3 km2
). However, because of the
relatively long drifting stage, juveniles are
likely to become distributed in areas some
distance from the reserve. This suggests
that the following option is ideal;
work with neighbouring communities to
establish a network of small sea cucumber
reserves along the coast.