Sea Snakes, Rhinos, And The Close Observation Of Two Tragic Commons


Thanks as always to Conservation, and in this case to Jason G. Goldman for the excellent summaries of scientific findings each week. There is not much happy news in this story, but nonetheless it is critical reading because of the detailed observation of the scientists:

Each month, hundreds of squid fishing vessels return to port in Vietnam loaded not just with squid, but also with sea snakes harvested from the Gulf of Thailand. Each month, the seven major snake processing facilities move an average of 6,500 kilograms of sea snakes, which are sold for between $10 and $40 per kilogram, depending on species. By comparison, squid sell for between $7 and $20 per pound, making sea snakes the more lucrative catch.

In the most recent issue of the journal Conservation Biology, Vietnam Academy of Science and Technology researcher Nguyen Van Cao and colleagues argue that the harvest of sea snakes from the Gulf of Thailand is perhaps the world’s largest systematic exploitation of marine reptiles in the world, but it’s one that is woefully ignored or, at best, underscrutinized.

For five years, the researchers observed the trade in snakes as they changed hands from fishing boats to middlemen, from middlemen to merchants, and as the live snakes were packed up for shipping by road, rail, boat, or plane. In addition, they interviewed 30 captains of squid vessels, 30 crewmembers, 20 middlemen, and a handful of merchants, workers in their processing facilities, and physicians in local hospitals. Because so little is known about the trade in sea snakes, the researchers simply wished to determine the geographical and temporal extent of the harvest, which species were harvested and how much, and what the socioeconomic factors were that drove the trade.

Most of the sea snakes came in on squid fishing vessels to the two major harbors in Vietnam’s Ca Mau Province, Song Doc and Khanh Hoi. Together, those two harbors are home to the country’s seven major sea snake merchants.

Once the snakes were transferred from fishing vessels to middlemen, the middlemen (who pulled a profit by paying the fishermen less than they received from the merchants) moved them to the merchants. There, they were sorted into two class sizes, with smaller individuals being less than 500 grams, and larger ones weighing more. The snakes were placed into Styrofoam boxes containing tap water and salt, air holes were poked into the top, and it was sealed with tape. Each container held some 17-18 kilograms, which equaled as many as 40 large or 60 small snakes.

The snakes are used for meat, their blood is infused into alcohol (“enhancing health and virility”), the organs are used for alternative medicine (gall bladders in particular are thought useful for pregnant women), and they also become ground into a sort of glue which is purported to cure joint pain, back pain, anorexia, insomnia, and to strengthen tendons and bones. The health effects are, predictibly, dubious.

Most of the snakes were from just two species: Lapemis curtus and Hydrophis cyanocinctus. The remaining fifteen percent was comprised of an additional six species:Acalyptophis peronii, Aipysurus eydouxii, Hydrophis atriceps, H. belcheri, H. lamberti, and H. Ornatus. Based on the researchers’ assessments, all were sub-adult or adult individuals, though some females wound up giving birth after they were caught, leaving some newborn infants in the mix as well.

Despite the fact that each of these species is listed by the IUCN as either “learn concern” or “data deficient,” catch rates reveal that, at least in the Gulf of Thailand, populations are dwindling. In 1995, just 25-30 squid vessels were also harvesting snakes. By 2013, that number had increased to 900. “Most squid vessel captains reported harvesting sea snakes as a valuable bycatch that requires negligible additional effort,” write the researchers, and they’re now become expected to bring snakes back with them. That harvest is perhaps aided by the fact that tracking of sea snake exploitation and enforcement of whatever regulations are in place “is virtually nonexistent.”

As a result, from 2009 to 2012, there was a statistically significant reduction in the total biomass of sea snakes harvested. In 2009, more than 100 tons were processed through the merchant facilities, representing some 275,000 individual snakes; 84 tons in 2010; 78 tons in 2011; and just 68 tons in 2012. The actual number of harvested individuals is likely quite higher that the estimates, since the researchers focused just on Vietnamese fishing vessels, ignoring those from Malaysia and Thailand which also harvest snakes from the Gulf of Thailand.

The findings suggest that despite their IUCN classifications, a large subset of sea snake species in the Indonesian archipelago – a landscape known for high marine biodiversity – is in danger of having their populations damaged or destroyed thanks to unsustainable fishing practices. 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, laments Nguyen. “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.”

The handsome price fishermen can be paid for snakes is reflected in the wanton disregard they have for their own personal safety. Marine snakes are some of the world’s most venomous, and there is no anti-venom for most of them because they’re so understudied relative to Earth’s other venomous critters. Despite that, they’re often handled without gloves, and workers often walk around barefoot in tanks containing live snakes.

One popular remedy for snakebites? Rhino horn, either applied directly to the bite, or ground into a paste and swallowed. Thus, there is a direct, heartbreaking link between the pointless, brutal slaughter of rhinos for their horns, and the unsustainable harvest of sea snakes in the Gulf of Thailand. Two systematic wildlife crimes, thousands of miles apart, each facilitating the other. – Jason G. Goldman | 21 November 2014

Source: Van Cao, N., et al. (2014). Sea Snake Harvest in the Gulf of Thailand, Conservation Biology, 28 (6) 1677-1687. DOI:

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s