Academic editor: Mark Auliya
Assessing the sustainability of the harvest of animals can be done by obtaining data from processing facilities and establishing that vital attributes of the harvested animals (e.g., size, age structure, sex ratio) do not change over time. This model works if the traders operate in a free market without any regulations on what can be harvested, processed or exported, and when harvest methods and harvest areas do not change between assessment periods. Several studies assessed the harvest effects on blood pythons (
Nijman V (2022) Harvest quotas, free markets and the sustainable trade in pythons. Nature Conservation 48: 99–121. https://doi.org/10.3897/natureconservation.48.80988
Several studies have addressed the unsustainable exploitation of reptiles (
In natural resource management the concept of sustainability is central as it would allow to maintain a long-term yield. From an economic perspective obtaining the largest harvest while maintaining the harvested population at a given size indefinitely (or at least long term) is preferable. This is known as the maximum sustainable yield (
As with all assessments over time the definition of the parameters needs to be the same in both assessments. If a population is initially defined as the number of mature individuals, then it cannot be changed to the total number of individuals later on. Likewise, the area under consideration cannot become increasingly larger over time. From Fig.
Conceptual framework of the relationship between population size, sustainable harvest and global conservation status. The harvest that took place between A and B, C and D, and E and F, could be considered sustainable, whereas it is unsustainable between B and C and D and E. The global threat assessment based on two of the IUCN threat level criteria (population size and declining populations) are not tightly linked to harvest sustainability (modified after
Relationships between the legality of harvest and trade and its sustainability, with examples from reptiles in Indonesia, based on harvest quotas allocated for 2021 (
Legal | Illegal | |
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Harvest of 750 tokay geckos ( |
Harvest of 250 tokay geckos from the province of Central Kalimantan |
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Harvest of 1,992,750 tokay geckos from Java | Harvest of 10,000 s pig-nosed turtles ( |
Several studies reported on the sustainability of the harvest and trade in blood pythons
Using publicly available information I here establish if there is sufficient data to assess whether blood pythons are indeed exploited sustainably. Specifically, I assess the following:
Is there a sufficient time between the first and the second assessment period, and if so (a.) do methods of harvest remain the same (or largely similar) between the two assessment periods; (b.) has access to harvest areas changed over the assessment period; (c.) has the harvest area remained the same; (d.) has the regulatory landscape remained the same
Is there evidence for illicit trade in blood pythons and if so (a.) does this happen at the national or provincial level; (b.) does this happen at the international level.
The blood python is found in eastern Sumatra and Bangka, and smaller offshore islands of Indonesia and the Thai-Malay Peninsula (with one record in Vietnam near the Cambodian border:
Left: Blood python (
Blood pythons are not included on Indonesia’s protected species list, but their harvest and trade, both domestically and internationally, is regulated by a quota system (
Based on detailed observations in Indonesia between the mid-1990s to present, and through active participation in quota setting meetings, collaboration with NGOs and government bodies, and visits to numerous reptile traders, slaughterhouses, and processing facilities throughout western Indonesia, I gained an insight into the regulatory landscape of the reptile trade in Indonesia. In addition, for 12 years I was a member of the Dutch CITES Scientific Authority, with the Netherlands being one of Indonesia’s main wildlife trading partners (
The facilities where pythons are killed and skinned, have their gall bladders and meat removed, and where skins are cleaned, pegged to dry, and processed, are called slaughterhouses (rumah pemotongan or rumah potong in Indonesian) by most of the researchers (e.g.,
To assess if any illicit trade in blood pythons occurred within Indonesia, I first focussed on the annual harvest quotas for the province of North Sumatra in 2015 and compare them with data collected at various slaughterhouses (Table
Secondly, for comparison, I focussed on the province of South Sumatra.
Overview of visits to slaughterhouses to assess the sustainability of the harvest and trade in blood pythons (
Year (total days) | Snakes | Rantau Prapat | Cikampak | Sei Suka | Medan | Stabat | Simalungan | References |
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1996–1997 ( |
2,063 | 22 days | 13 days | |||||
2007–2008 (<31) | 260 | not specified | not specified |
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2010 (<90) | not specified | not specified | not specified |
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2014–2015 (24) | 1,020 | 8 days | 16 days |
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2014–2015 (24) | 1,020 | not specified | not specified | not specified |
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2015 ( |
541 | not specified | not specified |
In calculating the number of blood pythons that were processed in these slaughterhouses in 2015 I conservatively assumed that they are operational six days a week (from experience it is more likely that they receive snakes every day). I obtained harvest quota and export quota data from the website of the Indonesian Ministry of Forestry for the period 2008 to 2022.
The time between the first and the second assessment period in the blood python studies was taken from the data presented in Sianturi et al. (
To assess any illegal international trade, in January 2022 I obtained data on the trade in blood pythons from the CITES trade database for the period 2004 to 2020. This covers the trade in live blood pythons, skins and leather products. Data from 2021 was not yet available and prior to 2004 Indonesia did not recognise
Prices were normally quoted in Indonesian Rupiah; I corrected these for inflation to December 2021 and then converted them to US dollars.
In order to assess whether or not harvest is sustainable one needs at least two temporary separated assessment points.
There is clear evidence from North Sumatra that over the last decades there have been marked changes in the way blood pythons are harvested, from opportunistic capture to, at least in part, targeted collection. Likewise, the harvest area has changed as well.
In addition, there have been significant changes in infrastructure in Sumatra with the percentage of road sections that were > 80% paved increasing from 56% in 1995 to 71% in 2005 (
The economic and regulatory landscape of the blood python trade has changed considerably over the last two decades, making it difficult to disentangle whether any change that
Indonesia has an annual quota system in place for the harvest of both CITES listed and non-CITES listed species (Table
Harvest quotas for blood pythons in Indonesia (number of individuals for the live pet trade / number of individuals for the skin trade) for four selected years; export quotas are 90% of the harvest quotas. Bangka-Belitung was established as its own province in 2000; up to 2020 its quota was included in South Sumatra.
Province | 2008 | 2015 | 2020 | 2021 |
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Aceh | 0 / 2,850 | 0 / 10,000 | 0 / 10,000 | 600 / 7,100 |
North Sumatra | 1,500 / 21,090 | 1,500 / 17,840 | 1,500 / 18,000 | 1,500 / 20,000 |
Riau | 0 / 4800 | 300 / 4,900 | 0 / 4,900 | 0 / 4,900 |
West Sumatra | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 |
Jambi | 0 / 4,000 | 0 / 4000 | 0 / 4,000 | 0 / 4,000 |
Bengkulu | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 |
South Sumatra | 250 / 4,300 | 300 / 4,300 | 300 / 4,300 | 700 / 5,000 |
Bangka-Belitung | - | - | - | 0 / 0 |
Lampung | 750 / 4,000 | 0 / 0 | 0 / 0 | 0 / 0 |
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38,740 | 43,140 | 43,000 | 43,800 |
There is considerable evidence of unregulated and illegal trade in blood pythons and that they are harvested in numbers that are above the set quotas.
The overall trend of the export of whole skins from wild-caught blood pythons over the last thirteen years is downwards (Pearson’s r = -0.753, P = 0.003) (Fig.
The CITES trade database also gives some additional information on the legality of the trade in blood pythons. Various countries, including Singapore and Italy, report the international trade of 14,144 blood python skins that were at one point traded without proper permits (CITES source code ‘I’), all but seven of these skins, i.e., 99.9%, originated from Indonesia. The 14,137 illegally traded blood python skins that were intercepted, represent 3.0% of the total trade in blood python skins that was reported by Indonesia over this period. Accepting that only a proportion of the illegally exported blood python skins would be intercepted and then traded internationally, this suggests a significant illegal trade in the species.
There are some peculiarities in the export of live blood pythons from Indonesia over the last 17 years (Fig.
Finally, the trade in blood pythons from Indonesia is not restricted to whole skins or live animals. Indonesia is also the exporter of small leather products made from wild-caught blood pythons (it reports the export of 67,950 small leather products over the period 2004–2020, Malaysia reports the export of 2 small leather products over this period). For those years that Indonesia did report these exports (in 2013 and 2014 Indonesia did not report any export), on average 4,850 small leather products are exported. It is difficult to convert this to whole animal equivalents, and the export may occur years after the blood pythons have been harvested, but this adds to the export of whole skins and live blood pythons reported above.
Export of wild-caught blood python skins as reported by exporting range countries (red: Indonesia; black: Indonesia, Singapore, Malaysia, Thailand, Myanmar). Indonesia did not report any export for 2013 or 2014 and for these years data from importing countries was used. In 2009–2012 and 2019–2020 Singapore reported the re-export of large numbers of blood python skins from Indonesia, markedly above what was reported by Indonesia as being exported to Singapore, and this surplus has been added to the total.
Relationship between the annual number of live wild-caught blood pythons that Indonesia reports as being exported between 2004 and 2020 and the number of captive-born blood pythons it exports in that same year. Wild-caught blood pythons are subject to a harvest and export quota (between 1,890 and 2,250 individuals per year) whereas the export of captive-born blood pythons is not subjected to a quota.
I here aimed to establish if there was sufficient data to assess whether blood pythons are exploited sustainably based on information that has been presented in the literature. The first question that needed to be answered was whether there was sufficient time between the first and the second assessment period for an assessment to be made. This varied greatly between studies, ranging from a few months to twenty years. The lower end of this is obviously too short to make an assessment of sustainability and the latter makes it unlikely that what is measured reflects just changes (or the absence of changes) in the population of blood pythons.
For the studies that assessed change over a longer period, it was clear that the methods, and quite likely intensity, of harvest had not remained the same, with more targeted collecting in the latter compared to the former periods. Likewise, there is good support that in North Sumatra access to harvest areas improved over time. Harvest areas had either been enlarged or significant shifts in harvest areas had occurred. As such any changes in the numbers or sizes or condition of the blood pythons that end up in trade may be due to changes in harvest methods or changes in harvest areas. Conversely, any non-change can be due to genuine stability of the population, or it can be due to harvesters moving to other areas or deploying different collecting strategies. The other areas may even include neighbouring provinces as suggested by
While
The predictions on how blood python populations were expected to change are based largely on the knowledge of the biology of exploited animal populations (
As noted by
Trade in live blood pythons from Indonesia, shows anomalies, whereby in the years that the maximum number of wild-caught individuals is reached, the number of blood pythons that are declared as captive-born (and not included in the annual harvest quota) that are exported actually increases. At least since 2019 it has not been allowed to harvest gravid female blood pythons from the wild and the captive-born and captive-bred blood pythons must have been derived from dedicated captive breeding facilities. It is questionable, however, that actual captive breeding blood pythons makes economic sense. As noted above, depending on the size, harvesters get paid between US$8–15 for a blood python (
The reason the Indonesian government, and in a global arena, CITES, sets limits on harvest and export, is to prevent species such as the blood python from being overharvested. In Indonesia, it is the Indonesian Institute of Sciences that provides the scientific justification for these limits (
It is possible that one of the outcomes of the studies by Shine et al. (1999),
While harvest quotas for different provinces, or indeed for Indonesia as a whole, differ little from year to year when seen over a longer time period some marked geographic changes are apparent (Table
Contrary to, for instance
Measuring sustainability is often done indirectly by testing predictions regarding what would happen if a harvest was not sustainable. These studies in general cannot demonstrate sustainability; at best all they can do is to demonstrate with a level of certainty that harvest is not not sustainable. Five studies commented or attempted to assess sustainability in the harvest of blood pythons in the province of North Sumatra using data from slaughterhouses to establish if vital attributes of the harvested animals changed over time.
As such, despite decades of commercial trade from North Sumatra, there is insufficient data to suggest whether the harvest and trade of blood pythons out of this province is sustainable. Data on the sustainability from other parts of the blood python’s range, including from southern Sumatra (Lampung, South Sumatra, Jambi, Bangka) where over the last decade ~100,000 individuals were allowed to be harvested, are lacking. There is, however, substantial evidence of underreported and illegal international trade in blood pythons. Part of any assessment of sustainability of the harvest and trade in blood pythons must address this as a matter of urgency.
I thank the Indonesian Institute of Sciences, the Ministry of Forestry, individual members of IRATA, and TRAFFIC Southeast Asia for their support over the years. Three reviewers and the editor provided very helpful suggestions for improvement, for which I am grateful.