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Oceans of Wealth in Sea CucumbersFarming and replenishing wild populations of tropical sea cucumbers could see coastal com-munities throughout the Indo- Pacific region supply the insatiable Asian demand for dried sea cucumber, according to Australian aquaculture scientist Dr Stephen Battaglene. Unceremoniously filtering the ocean floor, the sea cucumber (Holothuria scabra) is a slug-like fish, which extracts life-giving nutrients from the algae and bacteria it sucks out of seabed mud and sand.
From his four years of research in the Solomon Islands, Dr Battaglene developed methods to induce the variety of sea cucumber, sandfish, to spawn in land-based nursery tanks. A culinary delight in China and Asian nations, and highly prized for Chinese traditional medicine, the sea cucumber, also known as beche-de-mer or trepang, has been collected from the world's oceans for centuries. And as a result, stocks are becoming depleted. "It can take over fifty years for isolated and heavily harvested stocks to recover," he said. To help increase local populations, Dr Battaglene developed methods to get the sea cucumbers to spawn in captivity by using stimulation from heat, movement and alga feeding. "Thermal stimulation is the most commonly used spawning technique for sea cucumbers, although mature animals will often spawn spontaneously in response to collection and transport stress. Also, by following Japanese research on using dried alga as a spawning inducer, we found food to be a stimulus," he said. To help feed the larval sea cucumbers until they were old enough to be released into seabed farms, or the ocean to enhance wild stocks, Dr Battaglene established an algal unit. The Solomon Island project saw juvenile sandfish of up to 250 mm in length reared in land-based nursery tanks. "To date, seven successful hatchery trials have been conducted with sandfish, resulting in production of more than 200 000 juveniles," Dr Battaglene said. Now a senior researcher with the Tasmanian Aquaculture and Fisheries Institute, Dr Battaglene worked with the International Centre for Living Aquatic Resources Management (ICLARM) in the Solomon Islands during his four years of research. The Australian Centre for International Agricultural Research also sponsored the sustainable sea cucumber farming project, which could help build the economies of many poverty-stricken Indo-Pacific nations. "Poor management of sea cucumbers deprives developing countries of much needed export earnings, so release of juveniles reared in hatcheries is a potential way of restoring wild stocks of sandfish," Dr Battaglene said. Dr Battaglene said an advisory panel of Australian scientists is confident the basic techniques now exist to produce juvenile sandfish in large numbers at reasonable cost to replenish depleted stocks. Of the 1400 species found worldwide, the sandfish is one of the most sort after of only twenty commercially valuable species. "They are highly valued, in great demand and occur naturally in large numbers in areas that are not overfished," he said. Trade in dried sea cucumber could brings benefits to coastal communities because harvesting, processing and storage is easy and it doesn't need specialised equipment. "A cottage industry is one of the things that the Aboriginal people are interested in doing, particularly in Western Australia where they are interested in the potential for stock enhancement and restoration of their stocks. By selling the product to China, people can make money and this would help them pay for medical supplies and education," Dr Battaglene said. In China and other Asian nations, dried sea cucumber is a prized delicacy used to flavour soups and stir-fries. No Chinese New Year, Hungry Ghost Festival or family celebration would be without a dish of 're-hydrated' dried sea cucumber. In traditional Chinese medicine sea cucumber is seen as an aphrodisiac and a cure for many illnesses such as arthritis, whooping cough, and high blood pressure. It is also valued for its anti-fungal and anti-bacterial properties. Dr Battaglene said conservative estimates put the total importation of sea cucumber into Hong Kong, Singapore and Taiwan in 1994 at US$60 million. "It is very hard to get a production figure from Australia, as much of the product harvested by Aboriginal and Torres Strait Islanders is sold to middle men before being marketed to Singapore, Hong Kong and Taiwan. The product can also be stored for long periods and it is hard to ascertain how much is actually being harvested." The pharmaceutical industry has also shown interest in the medicinal properties of sea cucumbers. And there is growing interest in the possible use of marine collagen extracted from sea cucumber for use in anti-aging treatments. Drs David Fairlie and Michael Whitehouse at the Centre of Drug Design and Development at the University of Queensland conducted research on rats in 1997, and found several promising medicinal properties: anti-inflammatory, anti-arthritic, anti-ulcerant, and anti-hypertensive. "Based on our data it seems highly probable that potential human therapeutic agents could be developed from sea cucumbers present in Queensland waters," they said. Another lucrative market derived from sea cucumbers is the dried intestines and dried gonads, which are favourite delicacies eaten by the Japanese. The sea cucumber can eviscerate itself, meaning it spews out its intestines when disturbed. It then regenerates this system in several weeks. Harvesters have taken advantage of this and milked the sea cucumber of its intestines and gonads, which are squeezed out, but soon grow back. Australia isn't the only nation eager to re-establish sea cucumber stocks. Dr Battaglene said sandfish are now being reared in several countries including Indonesia, India, Philippines, Ecuador, and USA on an experimental level in response to the ever-growing Asian market. Over-harvesting of sea cucumbers is a common tendency, but Dr Battaglene says Australia is still one of the few places left where you can find unharvested populations of sea cucumbers, which have the potential to be exploited. "The variety which have the most potential for enhancement at this stage are sandfish. Sandfish occur in Hervey Bay, Morton Bay, and in mangrove areas right throughout northern Queensland, the Gulf, and off Darwin and into Western Australia," he said. Dr Battaglene's reasoning is by restocking sea cucumbers back into the wild, aquaculture can lift naturally occurring populations. Although sandfish have many attributes for stock enhancement, he says more research is needed to develop reliable and cost-effective hatchery techniques for spawning, mass rearing of larvae, and the survival of large releases of juveniles into the wild. By Heather Ellis Reference: |
