Conservation of sea snakes is virtually nonexistent in
Asia, and its role in human–snake interactions in terms of catch, trade, and
snakebites as an occupational hazard is mostly unexplored. In a recent paper in
Biological Conservation Nyguen et al
(2014) report data on sea snake landings from the Gulf of Thailand, a hotspot
for sea snake harvest by squid fishers operating out of the ports of Song Doc
and Khanh Hoi, Ca Mau Province, Vietnam. The information was collected during
documentation of the steps of the trading process and through interviewers with
participants in the trade. Squid vessels return to their ports once per lunar
synodic cycle and fishers sell snakes to merchants who sort, package, and ship
the snakes to various destinations in Vietnam and China for human consumption.
They are also used as a source of traditional remedies. Annually, 82 tons, roughly
equal to 225,500 individual snakes, of live sea snakes are brought to ports. Knowledge
of the harvest has been largely ignored and the rate of harvest constitutes one
of the largest venomous snake and marine reptile harvest activities in the
world today. In the harvest two species, Lapemis
curtus and Hydrophis cyanocinctus,
constituted about 85% of the snake biomass, and Acalyptophis peronii, Aipysurus
eydouxii, Hydrophis atriceps, H. belcheri, H. lamberti, and H. ornatus
made up the remainder. The results of this new paper establish a quantitative
baseline for characteristics of catch, trade, and uses of sea snakes. Other key
observations include the timing of the trade to the lunar cycle, a decline of
sea snakes harvested over the study period (approximately 30% decline in mass
over 4 years), and the treatment of sea snake bites with rhinoceros horn.
Emerging markets in Southeast Asia drive the harvest of venomous sea snakes in
the Gulf of Thailand and sea snake bites present a potentially lethal
occupational hazard.
The authors suggest that the Gulf of Thailand/southern
Vietnam is one of the largest harvests of venomous snake and marine reptiles in
the world. Yet sea snakes are not even mentioned in studies concerning reptile exploitation
in Asia or globally. This underreported status is particularly notable given
that the Indonesian archipelago has the highest marine species diversity in
general and specifically is among the areas ranked as having the greatest
richness of sea snake species on Earth. Still, in this area an unexplained decline
of sea snakes has been reported. The eight commercially traded sea snake
species reported on represent a significant proportion of the 20 species known
in the Gulf of Thailand and of the 25 species known from Vietnam, including the
South China Sea.
Globally, 9% of sea snakes are threatened, 6% are near
threatened, and 34% are data deficient, as defined by the International Union
for the Conservation of Nature (IUCN). The species in this study, as well as
all other species known from the Gulf of Thailand, are currently categorized as
either least concern or data deficient. However, the results suggest that in
the Gulf of Thailand a large subset of the sea snake species now considered as least
concern or data deficient may, in fact, be in danger of having their
populations damaged or destroyed through over harvesting. According to the results
presented in this paper, the number of sea snakes harvested from the Gulf of
Thailand by boats based at the study sites was 6.35 specimens per square kilometer per year. The
authors could not exclude the possibility that sea snake species in addition to
those observed were traded from other harvesting grounds (e.g., harvest landing
in Vung Tau, Vietnam). The volume of harvested sea snakes
documented is a conservative estimate of the total harvest from the Gulf of
Thailand. It is very likely that more snakes were harvested by squid vessels
and trawlers that originated from ports in Malaysia and Thailand. Sea snakes
have been brought into the ports of Songkhla, Thailand, Kra Isthmus, Thailand, and
Endau, Malaysia. Sea snake harvests similar to the one reported here could be
occurring in (or spread to) other areas of the South China Sea and wider
Southeast Asia. Ten years ago in Quảng Ng˜ai, the sea snake bycatch was
discarded due to fear of bites and a lack of market; however, in 2011 their
price was US$10–35/kg. Knowledge of the biology of sea snakes and their role in
the ecosystem is limited. Thus, understanding of the effect that this harvest may
have on populations or on the wider ecosystem is limited. The results supply
evidence that the mass of snakes harvested from the Gulf of Thailand has been
decreasing since 2009, and fishers interviewed consistently reported a decline
since they first began capturing sea snakes as a commodity.
Snake bites during the trade process are occupational hazards
that carry a high risk given the lethal venoms and lack of availability of
antivenin therapy. The economic incentive of harvesting sea snakes, from the
fishers’ and merchants’ perspectives, clearly outweighs the snake bite risk.
With respect to fatalities the authors report, one affected family continued trading
in sea snakes, while another family terminated participation in the snake
trade.
The authenticity and effectiveness of rhinoceros horn
and other locally used remedies for snake bites remains unproven. Yet, use of
rhinoceros body parts in Vietnam has been directly linked to poaching of
rhinoceros in South Africa. The observation suggests a link between rhinoceros
poaching and sea snake harvest in the Gulf of Thailand. Both fishers and merchants take advantage of
emerging market opportunities. According to the merchants, government, and
nongovernmental officials interviewed, the large-scale harvest of sea snakes from
the Gulf of Thailand is tied to economic prosperity and thus increase demand
domestically in Vietnam and from China for snake products. The demand is due to
the perceived health benefits of sea snakes and consumption of sea snakes as
status
Items. This particular sea snake harvest has been
going on essentially unnoticed by national and international conservation organizations
for more than a decade, in part because it apparently does not overtly conflict
with Vietnamese laws. Yet, given the volume of snakes and the wide spectrum of
species extracted and that the environmental effects of the harvest are
unknown, immediate attention by conservation organizations to sea snake
harvesting appears warranted. Ironically, the enforcement of laws aimed at
managing the trade in widely harvested terrestrial snakes, such as various
cobra species (e.g., Naja spp., Ophiophagus hannah), may have the
unintended consequence of increasing the market for sea snakes.
Citation
Nguyen C, Nguyen TT, Moore A, Montoya A, Rasmussen AR Broad
K, Voris HK, Takacs Z. 2014. Sea Snake Harvest in the Gulf of Thailand. Conservation
Biology 28: 1677-1687.