aquaculture

Craig Schiller, from the Zoology Department, The University Of Queensland, Australia, authored a report entitled Assessment of the Status of the Coconut Crab Birgus latro on Niue Island with recommendations regarding an appropriate resource management strategy. The report (now available online) was first published by the FAO in April 1992 as part of the South Pacific Aquaculture Development Project, Suva, Fiji.

From the introduction:

A series of management proposals were developed to ensure the continuation of the coconut crab on Niue. A summary of the recommendations follows:

1. No female coconut crabs with large orange-tinted abdomens or bearing external eggs to be taken or interfered with.
2. Introduction of a minimum legal hunting size of 36mm thoracic length for all coconut crabs (includes providing a size-guide for hunters to use in the field to size crabs).
3. Banning of all coconut crab exports.
4. Introduction of closed hunting seasons.
5. A comprehensive public awareness campaign (involving production of a large coconut crab conservation poster and educational video movie).
6. Establishment of formal coconut crab sanctuaries.
7. Banning use of dogs by coconut crab hunters.
8. Instigation of a coconut crab monitoring programme.
9. Preservation of coconut crab habitat.

Its large size (up to 1 metre) and land-based behaviours suggest Coconut Crab is a species with the potential for aquaculture, but there is very little published research available. It has been noted that wild populations of Coconut Crab are shrinking in the Cook Islands. H. H. Taylor, P. Greenaway, and S. Morris published a report (1993) in the Journal of Experimental Biology entitled Adaptations to a Terrestrial Existence by the Robber Crab Birgus latro – osmotic and ionic regulation on freshwater and saline drinking regimens.

Milkfish has been cultured throughout Asia for many years. In the Philippines there has been a steady and substantial demand for milkfish or bangus as is known locally. According to the Philippine Department of Agriculture, milkfish ‘has been doing well in the international market with Philippine export of frozen or chilled bangus reaching over 526 metric tons or some P8.5 million annually.’ The Philippine Department of Agriculture has published an overview of the semi-intensive culture of milkfish.

Kee-Chai Chong, Ian R. Smith, and Maura S. Lizarondo have published, through the United Nations University (1982), a substantial paper entitled Economics of the Philippine Milkfish Resource System.

From the preface:

Considerable research has been conducted on milkfish in the Philippines. However, the available publications are scattered, and no attempt has been made in recent years to consolidate this information so that a concise appraisal can be made of the entire milkfish resource system, from fry gathering through dealers and nursery, rearing pond, and fishpen operators to marketing. The dual purpose of this paper is to provide such an overview of the Philippines milkfish resource system and to evaluate its efficiency.

SEAFDEC Aquaculture Department (2005) has published a Code of Practice for Sustainable Use of Mangrove Ecosystems for Aquaculture in Southeast Asia.

Objectives of the Code of Practice
• To define principles, guidelines, and best practices for responsible aquaculture in mangrove ecosystems in Southeast Asia
• To provide a tool to guide States, non-government organizations, research and academic institutions, aquaculture practitioners, mangrove managers, local communities, global and regional aid and financial institutions, and other stakeholders concerned with both responsible aquaculture and the conservation and sustainable use of mangrove ecosystems
• To recommend key legislation and enforcement mechanisms to ensure both responsible aquaculture and the conservation and sustainable use of mangroves.

From the introduction:

Mangrove ecosystems (or simply ‘mangroves’) are the tide-influenced wetland complex consisting of mangrove forests, estuaries, lagoons, and associated habitats along the coasts and around islands in the tropics and subtropics. The mangrove forest consists of seawater-adapted flowering trees and shrubs, and the many associated ferns, fungi, and algae, including many epiphytes. The ‘true mangrove’ plants are members of the genera Rhizophora, Bruguiera, Ceriops, Avicennia, Sonneratia, Xylocarpus, Heritiera, and Excoecaria.

Mangroves support microscopic to large, terrestrial and aquatic (marine and freshwater), transient and resident wildlife. The mangrove physical environment includes waterways, mudflats, salt pans, and islands, with a wide ranges of salinities, daily tidal flood and ebb, and anaerobic mud bottoms.

The proceedings of a workshop held at Nong Nuch Village, Pattaya, Thailand, 27-31 May 1985, sponsored by the United Nations University and the National Research Council of Thailand have been edited by Peter Kunstadter, Eric C. F. Bird, and Sanga Sabhasri; and are available as an online book.

Subtitled The Socio-economic Situation of Human Settlements in Mangrove Forests, the introduction has this to say:

More than half the world’s people live in coastal regions, utilizing such resources as salt, minerals, fish, and crustaceans, the products of mangroves, salt marsh, seagrass, and kelp, energy from wind, waves, and tides, and such materials as sand, gravel, clay, and limestone, all obtained from the coast or the adjacent sea. Moreover, the coast provides sites for settlement, agriculture and aquaculture, ports and harbours, industry, commerce, and recreation. The management of coastal environments and their resources has raised many problems in both developed and developing countries, and it was felt appropriate that the United Nations University should give emphasis to this field of study.

The Coastal Resources Management Project was initiated as part of the University’s Natural Resources Programme. It was decided that the coastal environment – comprising the foreshore (between high and low tide lines), backshore (above high tide line to the landward limit of marine influences), and nearshore (from low tide line out to a depth of 20 metres) zones was a distinctive field for research and training that merited its own project within the programme.

A number of research studies and workshops were commissioned under this theme. Man in the Mangroves contains papers presented at a UNU-sponsored workshop. Three of the papers result from UNU research. The remainder were submitted by independent researchers. They focus on the socio-economic aspects of the use, development, and management of mangrove areas in relation to environmental and ecological factors.

Although the Coastal Resources Management Project has now been concluded, the University’s new programme on Resource Policy and Management has undertaken to maintain an international dimension in research, training, and dissemination, stressing the interaction of resource management, conservation, and development.

Mangroves have always naturally protected tropical coastlines from erosion. More recently, shrimp farms have applied pressures to the natural forests. In response to the clearing of the forests, mangrove ‘greenbelts’ are being used to prevent coastal erosion.

Joan Martinez-Alier, from the Department of Economics and Economic History, Universitat Autònoma de Barcelona, Spain has published a report entitled Ecological Conflicts and Valuation – mangroves vs. shrimp in the late 1990s. From the abstract:

Shrimps are produced in two different ways. They are fished in the sea (sometimes at the cost of turtle destruction) or they are “farmed” in ponds in coastal areas. Such aquaculture is increasing around the world as shrimps become a valuable item of world trade. Mangrove forests are sacrificed for commercial shrimp farming. This paper considers the conflict between mangrove conservation and shrimp exports in different countries. Who has title to the mangroves, who wins and who loses in this tragedy of enclosures? Which languages of valuation are used by different actors in order to compare the increase in shrimp exports and the losses in livelihoods and in environmental services? The economic valuation of damages is only one of the possible languages of valuation which are relevant in practice. Who has the power to impose a particular language of valuation?

From the Introduction:

In many coastal areas of the tropical world, in Ecuador, Honduras, Sri Lanka, Thailand, Indonesia, India, Bangladesh, Philippines, Malaysia, there is social resistance against the introduction of shrimp farming for export, since this implies the uprooting of mangroves in order to build the ponds. In such areas, poor people live sustainably in or near the mangrove forests, by collecting shellfish, by fishing, by making use of mangrove wood for charcoal and building materials. The mangroves are usually public land in all countries, being in the tidal zone, but governments give private concessions for shrimp farming or the land is enclosed illegally by shrimp growers. Illegality is prevalent not only because of the public character of the land, but also because there are often specific environmental laws and court decisions protecting the mangroves as valuable ecosystems.

Shrimp or prawn production entails the uprooting of the mangroves, and the loss of livelihood of people living directly from, and also selling, mangrove products. Beyond direct human livelihood, other functions of mangroves are also lost, perhaps irreversibly, such as coastal defence against sea level rise, breeding grounds for fish, carbon sinks, repositories of biodiversity (e.g. genetic resources resistant to salinity), together with aesthetic values. Pollution from the shrimp ponds destroys the local fisheries. Also, wild shrimp disappear because of the loss of breeding grounds in mangroves and because they are overharvested as seed for the ponds.