The fishing fleet in Mazizini with scuba diving tanks and middlemen trading with catch in the foreground. Photo: H. Eriksson

Sea cucumber harvesting

Scuba-diving bandits

Sea cucumber harvesting in the Western Indian Ocean needs better management

Since at least the 18th century sea cucumbers have been an exclusive culinary to people in Far East Asia. Nowadays, they are harvested and traded in most of the tropical world, having expanded from its origin in the central Indo-Pacific.

While largely unknown in the English-speaking world, sea cucumber (trepan or bêche-de-mer) fisheries have existed for around a century in the Western Indian Ocean. These animals are relatively easy to harvest in coastal areas and is therefore an important source of income to many people who otherwise lack income alternatives.
Destructive boom-and-bust
Globally, existing institutions have generally failed to secure a sustainable harvesting of sea cucumbers. The result is a destructive boom-and-bust pattern and a high level of illegal, unregulated and unreported scuba-diving for sea cucumber fishing.

In a recent study centre researchers Maricela de la Torre-Castro, Per Olsson and lead author Hampus Eriksson from the Dept. of Systems Ecology (also associated to the centre's NEREUS programme) analysed the scuba diving fishery and trade in Zanzibar (Unguja Island) in East Africa.

"The fishing for sea cucumbers in the area is a complex matter with several actors operating at different levels, from local fishers, via middlemen and multinational networks to consumers predominantly in China," Maricela de la Torre-Castro explains.
Roving fisheries
The study, which was published in PLoS ONE, was based on interviews, discussions, participant observations and catch monitoring in seven sites in Zanzibar. The findings conclude that the scuba-diving fishing in Zanzibar, predominantly targeting sea cucumbers but also other high value marine resources, fits the description of opportunistic roving bandits that lack incentives to govern and preserve.

Such roving dynamics in fisheries have predominantly been addressed on a global scale, but this study shows that it also takes place at a considerably smaller spatial scale. The study thereby illustrates the complexity in governing these fisheries.

"Roving fishery actors take advantage of missing institutions in favour of personal profits. This comes at a cost of deteriorated resilience of the marine ecosystems and has negative consequences for coming generations," says Per Olsson.

The fishery's split personality
The authors conclude that the sea cucumber fishery in Zanzibar is in fact split into two distinct varieties: the village-based near-shore fishery and the more industrialized mobile "roving bandit-style" scuba-diving fishery.

Although the two fishing varieties are connected because the products transit via the same exporters, the identification of the two segments is crucial because of their different management requirements. The image of a simplified fishery situation must therefore be replaced by a more complex one with multiple types of fisheries targeting sea cucumbers.

While reformed local management may suffice for improving the situation of the near-shore segment of the fishery, the more mobile and industrialised scuba-diving segment require new institutions that match the scale of the operation.

Wanted: an institution with a mandate
Given the structure of the scuba-diving fishing, the authors argue that regional governance partnerships is crucial for improved understanding and management.

Unfortunately, such efforts are still lacking.

"Although there are organizations in the region that have taken a strong position in understanding the resource and fishery, we are concerned to what extent there are any international institutions with real mandate for decision-making, or with an agenda to push new policy, that can drive collective participation in the governance of regional fishery operations such as this one," says lead author Hampus Eriksson.

Olsson, de la Torre-Castro and Eriksson also warn that there are several inequality and poverty aspects behind the current situation. Lack of livelihood alternatives and economic poverty promote an amplifying feedback on the destructive conduct of this fishery and many young men suffer dangerous health problems from the diving involved.

Hence, solutions to escape such traps should focus on identifying and breaking both socio-economic and ecological feedbacks that keep the system on its current destructive path.



Eriksson H, de la Torre-Castro M, Olsson P (2012) Mobility, Expansion and Management of a Multi-Species Scuba Diving Fishery in East Africa. PLoS ONE 7(4): e35504. doi:10.1371/journal.pone.0035504