Fishing for sea cucumbers– how long can this go on?
Sea cucumbers look completely unappealing — like sausage-shaped animal droppings on the sea floor. Yet, these relatives of sea stars and sea urchins are extremely intriguing biologically. Although they are soft-bodied, they have a compound in their skins called ‘catch’ collagen that has the amazing capability of liquefying or solidifying based on signals from their nervous system. When the animal is threatened, catch collagen softens, allowing the animal literally to pour itself into a crevice and then immediately harden the collagen, so that it cannot be dislodged.
Sea cucumbers are found worldwide in temperate and tropical oceans, in deep and shallow seas. The greatest diversity of sea cucumbers is found in the Indo-Pacific region, where they are common in shallow, coastal waters.They are ecologically important as detritivores (‘dirt’ eaters) that function like ocean vacuum cleaners, moving sluggishly along the ocean floor, mopping up dirt and cleaning the ocean floor of debris and bacteria.
Worldwide, there are about 1,700 species of sea cucumbers. Of these, about 60 species are recognised for their food and medicinal value,especially in the Far East. The trade of sea cucumbers from Southeast Asia to China began some 1,000 years ago but in the last few decades, the demand for these strange creatures has increased steadily. West Central Pacific countries and Asia import 20,000 to 40,000 tonnes of sea cucumber products per annum.
Because these animals are slow-moving in shallow waters, divers either wade or dive in and simply pick up the animal. In deep waters, sea cucumbers are harvested by skin divers (with flippers, a face mask and a snorkel) or scuba divers (with portable air supplies) who dive from traditional oru, or fibre reinforced plastic boats with outboard motors.
After harvesting, the sea cucumbers are processed (graded, cleaned, eviscerated, boiled; stored in salt; boiled again and dried) prior to export. In the Far East and Southeast Asia, processed sea cucumbers, called bêche de mer (French for sea spade) or trepang (a derivation from the Malay word for sea cucumber), are considered a culinary delicacy. They are also used in Traditional Chinese Medicine as a tonic, to treat kidney ailments and arthritis.
Overexploitation of sea cucumber is rampant and reaching unsustainable levels. For example, over harvesting resulted in the extinction of these species in Egypt and caused severe depletion in India. Only a few, newly identified locations worldwide have healthy stocks of sea cucumber.
The bêche de mer industry in Sri Lanka is old, and it was recorded in 1917 that these animals had been traded with China for about thousand years. Until the end of the internal conflict in 2009 much of the sea cucumber related fishery was carried out in the North Western coast from Puttalam to Mannar and from Trincomalee to Kalmunai, in the east. There are about 4,500-5,000 families directly dependent on sea cucumber fishing, thus highlighting the importance of establishing sustainable harvesting practices.
In Sri Lanka, sea cucumber fishery is an open-access, unregulated fishery. Sea cucumbers from Sri Lanka are exported mainly to China, Hong Kong, Singapore and Taiwan, with Hong Kong (also a re-export hub) receiving more than 50% of the quantity. A kilogramme of perfectly formed, processed high-value species can fetch as much as 300 USD (nearly 40,000 Sri Lankan rupees). Prices for bêche de mer have risen considerably over the years. There are sea cucumber varieties with medium value, low value and no value. The high value species fetch between Rs. 600-1,200 per kilogramme, while medium-value species fetch about 500 rupees.
In Sri Lanka too, the fishery is showing signs of stress. For example, there are more and more boats engaged in sea cucumber fishery. Therefore, fishermen have to go further out to sea to find these animals. Recent trends show that fewer high-value species are being harvested, indicating signs of declining populations.
In post-war Jaffna, the situation for the sea cucumber fishery is much the same, as for the rest of the country. Sea cucumbers are picked up by skin divers in the coastal and offshore areas of the Jaffna lagoon. In Kurunagar, fishermen fish off trawlers for sea cucumbers. In the short space of five years, there has been uncontrolled overexploitation.
The impact of this intensive fishing is apparent: in 1983, a master’s degree student Pathmini Elanayagam examined the abundance of sea cucumbers in the Jaffna Lagoon and found that between 1980 and 1981, there were 20-160 individuals of high-value Holothurianobilis (English: Black teat fish; Sinhala: Polangaattaya; Tamil: Kalattai) per square metre. However, a recent study of 29 sites in the Lagoon found only 10 locations had any sea cucumbers at all. The total number in the 10 sites was only 360 individuals.
This recent study was funded by the Mangroves for the Future (see box) Programme and carried out for six months between October 2013 and June 2014 by the Department of Fisheries, University of Jaffna, with Professor Sivashanthini Kuganathan, Head, Department of Fisheries as the principal investigator.
The objective of the study in Jaffna Lagoon was to identify species diversity and abundance of sea cucumbers. In addition, Professor Kuganathan’s team also assessed the ecology of the sites where each species were found. The idea was to find types of environments where sea cucumbers were found and assess their ecological characteristics, so that these characteristics could be replicated in other areas to rehabilitate the sea cucumber fishery, given that the natural recovery of sea cucumber stocks is very slow.
The team initially had discussions with a selected group of fisheries cooperative societies, fisheries inspectors, the Assistant Director for Fisheries in the region, as well as individual fishermen. From these meetings, the team identified 29 sites for sampling of ecological parameters, fortnightly. Skin divers were employed to collect sea cucumbers in a one metre square — with no luck. The area was then increased to 6 x 200 m and individuals per hectare were calculated. Incidentally, out of the sixteen species recorded during the study seven species had not been recorded previously in Sri Lanka!
The most common species were the high-value Holothuriascabra (English: Sand fish; Sinhala: Jaffna attaya; Tamil: Jaffna attai/Vellaattai); and the low-value Stichopusnaso (English: Warty sea cucumber; Sinhala: no name; Tamil: Mulattai). The team’s analyses showed that each of these species had specific habitat requirements.
The team also studied sea cucumber processing centres in the district, and found that six species of sea cucumbers were processed — the Sand fish, Holothuriaspinifera(English: Brown sandfish; Sinhala: Disco attaya; Tamil: Raja attai/ Disco attai); Holothuriaatra(English: Lollyfish; Sinhala: Narriattaya; Tamil: Kuchiiattai), Holothurialeucospilota(English: White threadfish; Sinhala: no name known; Tamil: Paambuattai), Actinopygamiliaris(English: Blackfish; Sinhala: Kaluattaya; Tamil: Karuppuattai); and the Warty sea cucumber. Through their assessment, the team found that catches declined from May to September each year.
As a result of the detailed investigation, the team was able to examine and highlight which ecologicalcharacteristics are necessary for the restoration of sea cucumber stocks. In consultation with their stakeholders, the team developed a set of guidelines for the culture of sea cucumbers in the Jaffna Lagoon. They identified specific locations where the pilot projects should be commenced. Although the team recommended the culture of both common species, namely, the high-value Sand Fish and the low-value Warty Sea cucumber, fishermen flatly refused to culture the low-value species.
There was consensus among the scientists and fishermen that stocks were under serious threat and declining and that an initiative to reverse the trend is essential and urgent. There was unanimous agreement among the stakeholders to adopt a number of self-imposed bans/restrictions on: a) trawl fishing — that damages the sea floor — in sea cucumber habitat; b)harvesting small-sized cucumbers; c) skin diving with light, which disturbs other species and d) sea cucumber harvest from May to September.
This study used a pragmatic approach to a knotty problem. Stocks are declining, but this is a high-income, easy fishery. Therefore, it is nearly impossible for a conservation biologist to instruct fishermen “Don’t fish for sea cucumbers.”The approach undertaken with the support of MFF has been to gather scientific data, and show these data to fishermen, collaborating with them to figure out how stocks can be boosted. This use of scientific knowledge to make practical, on-the-ground decisions and most importantly, to include the resource users in decision-making, can be used as a good model to promote the sustainability of natural resources in non-fishery applications, as well.
As the American psychotherapist Nathaniel Brandon says, ‘The first step toward change is awareness. The second step is acceptance.’ This short project has achieved both.
| Mangroves For the Future (MFF) is a unique partner-led initiative to promote investments in coastal ecosystem conservation for sustainable development. Co-chaired by IUCN and UNDP, MFF provides a platform for collaborations among different agencies, sectors and countries, which are addressing challenges related to coastal ecosystem or livelihood issues. Operational in 11 countries, the goal of MFF is to promote an integrated ocean-wide approach to coastal management and to enhance the resilience of ecosystem-dependent coastal communities. The MFF Programme in Sri Lanka is managed by IUCN and funded by SIDA, NORAD and Danida. |