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SECTION
4 ECOLOGICAL RESOURCES CAPITAL STOCK
| 4.2 |
Existing
Capital Stock and Trends |
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| Marine
Reptiles
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| 4.2.2.21 |
The
only marine reptiles in Hong Kong are the
three species of chelonians which are sea
turtles, the Green Sea Turtle (Chelonia
mydas), the Olive Ridley Sea Turtle (Lepidochelys
olivacea) and the Leatherback Sea Turtle
(Dermochelys coriacea) as well as the occasional
sighting of one species of sea snake Hydrophis
cyanocinctus which has been seen swimming
in waters near to the shore (Karsen et al
1998). Sea turtles breed by laying their
eggs on sandy beaches at night. Breeding
adults return to nest at the beach where
they were hatched and then return to the
same beach in two or more years time (McGilvray
and Geermans 1997). During their breeding
season, the turtles migrate from their feeding
ground to mate in shallow waters off their
nesting beaches. The female comes ashore
two or more times a season on an average
of every three years to lay eggs in a nest
cavity on the beach (McGilvray and Geermans
1997; AFCD Homepage).
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| 4.2.2.22 |
The
Green Turtle (Chelonia mydas) is the only
one of the three species of sea turtles found
in Hong Kong waters known to breed locally.
The sandy beach at Sham Wan on Lamma Island
is the only documented nesting site for the
Green Turtle (Morton 1992). The beach and
the adjoining shallow shore at Sham Wan were
designated as a Site of Special Scientific
Interest (SSSI) in June 1999 and subsequently
listed as a Restricted Area in July 1999 such
that nesting sites, turtles, nests and eggs
are protected between 1 June and 31 October
each year. The Green Turtle (Chelonia mydas)
is a highly endangered species listed under
Appendix I of CITES, and is afforded protection
in Hong Kong under the Wild Animals Protection
Ordinance (Cap 170) , the Marine Parks Ordinance
(Cap 476) and the Animals and Plants (Protection
of Endangered Species) Ordinance (Cap 187). |
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| Marine
Fishes |
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| 4.2.2.23 |
Of
an estimated 1,800 species of fish on the
continental shelf of the South China Sea
(AFCD webpage, http://www.info.gov.hk/afd/conserv/
fauna.htm), over 300 species of marine and
estuarine fishes are found in Hong Kong
waters (ERM 1998a). Based on fishermen's
reported catches, it appears that the clupeids
(herrings, shads, and sardines), carangids
(jacks and pompanos) and sciaenids (croakers
and drums) are the dominant groups in Hong
Kong (ERM 1998a). As discussed in Paragraphs
3.3.2.57 - 3.3.2.810 - Agriculture and Pressures
on Capture Fisheries Resources, due to a
combination of fishing pressure, loss of
habitat and pollution impacts, the species
composition of Hong Kong's fish populations
over the past few decades has evolved from
large, slow-growing valuable, reef-associated
fishes, to smaller, fast-growing, low value,
water column fishes. One of the most vulnerable
of Hong Kong's marine fishes is the spotted
seahorse, Hippocampus kuda, which has been
observed in several areas of Hong Kong including
Lai Chi Wo, Double Haven and Sheung Sze
Wan, Sai Kung but is considered rare (ERM,
unpublished data). There are no species
of fish protected under either the Marine
Parks Ordinance or the Wild Animals Protection
Ordinance.
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| 4.2.2.24 |
An
ecosystem model of Hong Kong's marine food
chain was constructed based on a comprehensive
review of existing literature and showed
that well over half of the total biomass
was derived from plankton and zoobenthos,
such as marine worms. It was estimated that
marine fishes, including sharks and rays,
pelagic (ie water column) and demersal (ie
bottom-associated) fishes composed less
than 5% of the total biomass. The absolute
biomass of Hong Kong compared unfavourably
with the marine environment off the western
coast of Canada, but appeared comparatively
healthy in relation to an estimate for the
central South China Sea. However, it should
be noted that open ocean environments are
known to support lower biomass levels than
nutrient rich coastal environments such
as Hong Kong (ERM 1998e).
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