Subject: ABSTRACTS: DDT/PCBS in Hong Kong Dolphins & Finless porpoises in Asia (fwd)

Mike Williamson (pita@www1.wheelock.edu)
Sat, 29 Aug 1998 17:12:40 -0400 (EDT)

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Date: Fri, 28 Aug 1998 20:26:10 +0100
From: HWDT <hwdt@sol.co.uk>
Reply-To: Marine Mammals Research and Conservation Discussion
     <MARMAM@UVVM.UVIC.CA>
To: MARMAM@UVVM.UVIC.CA
Subject: ABSTRACTS: DDT/PCBS in Hong Kong Dolphins & Finless porpoises in              Asia

Below are abstracts of two recent papers on Asian cetaceans. Addresses for
reprint requests are attached.

Parsons, E.C.M. and Chan, H.M. 1998. Organochlorines in Indo-Pacific
hump-backed dolphins (Sousa chinensis) and finless porpoises (Neophocaena
phocaenoides) from Hong Kong. In The Marine Biology of the South China Sea
III (ed. B. Morton), pp. 423-437. Hong Kong: Hong Kong University Press.

Abstract:
Blubber samples from eight Indo-Pacific hump-backed dolphins (Sousa
chinensis) and eleven finless porpoises (Neophocaena phocaenoides)stranded
between 1993 and 1996, in Hong Kong waters, were collected for
organochlorine analysis. Levels of total PCB were low (0.19 m g.g-1 to 125 m
g.g-1 in S. chinensis and 0.47 to 17.3 m g.g-1 in N. phocaenoides) and are
similar to those typically recorded from other cetaceans. PCB concentrations
in calves (<1 year old) were generally half those of the adults.
PCBs were also detected in a sample of milk extracted from the stomach of a
calf. The concentrations of PCB in this sample were similar to those in the
blubber sample of the calf itself (2.49 m g.g-1 vs 2.32 m g.g-1).
Profiles of the major PCB congeners were similar between the two species.
Levels of chlorinated benzene, hexachlorocyclohexanes, dieldrin, chlordane
and mirex were low, generally below 1 m g.g-1 lipid. Total DDT levels,
however, were quite high. The median level of total DDT was 26.7 m g.g-1 for
S. chinensis and 50.3 m g.g-1 for N. phocaenoides. The relatively low
DDE/DDT ratios suggest that there may have been relatively recent releases
of DDT into the marine environment. The relatively high DDT levels may be a
cause of concern regarding the health of the animals.
The high neonatal mortality rate observed in Hong Kong's cetaceans may
partly be attributed to their compromised immune functions due to
organochlorine exposure.
Further studies are required to identify the effects of organochlorine
exposure on the resident cetacean populations in Hong Kong.



Parsons, E.C.M and Wang J.Y. 1998. A review of finless porpoises
(Neophocaena phocaenoides) from the South China Sea. In The Marine Biology
of the South China Sea III (ed. B. Morton), pp. 287-306. Hong Kong: Hong
Kong University Press.

Abstract:

The finless porpoise occurs in coastal and estuarine waters of the South
China Sea, ranging from Taiwan in the north to Indonesia in the south.
Morphological differences between the South China Sea and other populations,
notably the presence of a wide dorsal groove, have led to suggestions that
South China Sea animals may be a separate sub-species (Neophocaena
phocaenoides phocaenoides). Finless porpoises show age-related coloration
changes. In Hong Kong calves are blue-grey with white patches and adults are
dark grey, almost black. Their mating system appears to be promiscuous and,
considering their body and testis size, males probably rely on sperm
competition rather than intra-sexual competition. The reproductive season in
southern China is from November to March and studies in Hong Kong indicate a
high level of infant mortality during this period.
Finless porpoises, like other coastal cetaceans, are threatened by a range
of human activities, especially pollution, fisheries interactions and
habitat loss. The incidence of reported mortalities appears to be increasing
in areas such as Hong Kong and anthropogenic activities are believed to be a
contributing factor.

Please send reprint requests to:


E.C.M. Parsons, The Scottish Cetacean Research Programme, The Hebridean
Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, Argyll
PA75 6NU, Scotland.

Email: delphis@btinternet.com