aquaculture

China has a long history of aquaculture, but it is not always easy to get a sense of the scale of their inland aquaculture. The US National Oceanic & Atmospheric Administration (NOAA) library holds information resulting from the United States – China Living Marine Resources Exchange.

China is the largest fish producer in the world. Since 1990, fish production in China has ranked first in the world, reaching around 40 million tons in 1999 and accounting for 30 percent of the world total. At present, however, the industry is also faced with some problems such as fishery resource decline, environment deterioration, labor surplus and market stagnation. Like other industries in China, the fishery sector urgently requires a strategic restructuring in order to meet the changing international trading environment and to stimulate economic growth in the sector.

Tan Cheng Li, writing in the August 30, 2005 edition of the thestar.com.my, comments that nations hit by the December 26 tsunami are now planting mangrove trees along coastlines to create ‘greenbelts’ or vegetated strips of land, in the hope of preventing further erosion of damaged shores as well as to shield them from future giant waves.

Mangroves are something of a rarity – they cover a mere 0.04% of Earth’s surface and 0.12% of its land area, and whatever mangrove resource that remains should be conserved. There is an economic benefit to this as well.

In Malaysia, it costs RM15,000 to replant one hectare of mangroves. The government has identified 4,016ha of degraded mangroves requiring rehabilitation at a cost of RM110mil. Some 151ha have been replanted so far.

Impact of the tsunami
The December 26 tsunami left behind extensive environmental damage across the region. It totally changed coastal landscapes and ecosystems. The impact included:
# Loss and degradation of mangrove and seagrass beds
# Silting and degradation of coral reefs
# Change in tidal flats and coastal lagoons
# Uplifting of the seafloor in some areas
# Turbid coastal water
# Scouring of coastline
# Inland deposition of sand
# Salination of coastal land
# Impact on fisheries

The role of mangroves during the tsunami:
# Reflect and resist tsunami energy, thus reducing the inundation depth and area.
# Trap driftwood and other debris, thus reducing human injuries and property damage.
# Prevent people from being washed out to sea.
# Reduce erosion of beaches and sand dunes which also act as barriers to tsunamis.

Research has been done into integrating mangroves and aquaculture into sustainable aquaculture-silvoculture systems.

Silvofisheries is a form of integrated mangrove tree culture with brackishwater aquaculture. It is a form of low input sustainable aquaculture. This integrated approach to conservation and utilization of the mangrove resource allows for maintaining a relatively high level of integrity in the mangrove area while capitalizing on the economic benefits of brackishwater aquaculture. Further extension of aquaculture to meet the needs of the rural poor may be tolerable provided it is carried out in a controlled manner outside those areas already heavily exploited and environmentally sensitive in an integrated program of conservation and utilization, such as silvofishery methods.

Research has also been conducted into Disused Shrimp Ponds: Options for Redevelopment of Mangrove. N.J. Stevenson describes that associated with the rapid increase in the production of cultured marine shrimp, has been large scale conversion of mangrove to shrimp ponds. Production in many regions has proven to be unsustainable, largely due to inappropriate construction methods, poor environmental conditions, overstocking and disease problems. A number of shrimp ponds are consequently unproductive and lie idle. Accurate assessments of pond disuse are difficult to obtain, however, unofficial estimates have suggested that as many as 70% of ponds may be disused after a period in production. Pond construction, shrimp culture and pond disuse lead to alterations to the physical and chemical properties of soil, hydrological conditions and the flora and fauna composition of the pond area. The case for restoration, or rehabilitation to a sustainable use, is strong. Consideration must be given to the causes of production failure, the environmental conditions remaining following disuse, the needs and preferences of pond owners and coastal managers, and technical constraints.

It could be considered to be quite unusual to find an academic from a scientific discipline to have a flair for the aesthetic. Luis Rocha manages the combination with aplomb. He has created a web site about coral reef fishes superbly illustrated with his own photographs.

Rocha explains some of the attractions of coral reefs:

The most striking feature of reef fish is their diversity, in terms of both species number and the range of morphologies. An estimated 4000 (18% of all living fishes) species of fish live on coral reefs and associated habitats of the Indo-Pacific and Atlantic oceans, and this number increases as new exploratory surveys are done.

Further examples of his reef fish photographs can be found at his online gallery. As might be expected from his scientific background, the photographs are not only beautiful, they are meticulously accurate.

Although still in the very early stages of development, tuna are being farmed in an increasing number of locations around the world. According to smartaqua, tuna are being farmed in South Australia (Thunnus maccoyii), Croatia (Thunnus thynnus), Japan (Thunnus thynnus), Spain and Portugal (Thunnus thynnus), Mexico (Thunnus thynnus, bigeye (Thunnus obesus), yellowfin (Thunnus albacares)), and Canada (Thunnus thynnus).

The Government of South Australia’s Department of Primary Industries and Resources have identified the farming of Southern bluefin tuna (Thunnus maccoyii) is currently the single most valuable sector of South Australia’s aquaculture industry. Southern bluefin tuna farming is unique to South Australia and its development in 1991 initially put South Australian aquaculture on the map.

Tuna farms are not always universally welcomed – the WWF reported:

On Sunday, 2 February 2003, a local referendum on the island of Vis, Croatia, stopped a new tuna-farming project from taking off. The community’s response is the first of its kind in Croatia. WWF applauds the community’s and local NGO Sunce’s firm stand against an activity which is damaging the environment and decimating the already over-fished wild tuna in the Mediterranean.

Croatia is the leading producer of farmed tuna in the Mediterranean, after Spain. In 2001, Croatian production reached 3,000 tons from its eight farms. A new tuna farming project was presented to the inhabitants of the island of Vis, in the Adriatic, as the only alternative for their economic future. When the community was invited to participate in a referendum on the issue, their vote was an emphatic “no” – 88% of the voters were against the project.

Other reports identify tuna breeding and farming in Croatia has been an economic success and thanks to the investments of Croatian expatriates, tuna farms have started cropping up along the coast. The fish are being bred in cages. The results after five years is that tuna farming seems to be one of the most successful investments in Croatia, and the domestically bred tuna has already become world-famous.

Several Kali fishermen from the island of Ugljan invested in a somewhat unknown field of fish-farming: tuna farmed in cages. The business was set up in 1995 with an initial capital of $2 million Australian dollars, with a further $5 million spent on the purchase of cages, fishing boats, and other infrastructure. It was the only farm of its kind in that part of the Mediterranean. Farmed tuna is becoming one of Croatia’s best-known export products.

According to an article published by Enaca, in 2005, the Rayong Coastal Fisheries Research and Development Center (Rayong CFRDC) made a breakthrough in mouse grouper Cromileptes altivelis larval rearing. The center uses the a simple recirculation system for their broodstock holding facilities. The broodstock tanks are rather small at 3×5×1.2 m. Although mouse grouper broodstock successfully spawn in these tanks, egg production is low, which limits fingerling production.

Rayong CFRDC also operates a large broodstock holding cage facility at nearby Koh Samet. This facility holds broodstock of several grouper species including P. maculatus, E. fuscoguttatus, E. lanceolatus, E. coioides, mangrove snapper Lutjanus argentimaculatus and cobia Rachycentron canadum. Like Trad, Rayong have not been able to spawn their P. maculatus broodstock, despite attempts at hormonal induction of spawning.

There is considerable interest amongst the private sector in Thailand in developing marine finfish hatcheries. There is already considerable production of seabass Lates calcarifer in Thai hatcheries, and many are keen to diversify their production to higher-value species such as groupers. A major constraint to diversification amongst private hatcheries is access to eggs and larvae. Many are now working with the government centers and stations so that when fertilized eggs are available in government facilities, they can obtain them for grouper larviculture trials. The government also provides training and technical support on grouper hatchery technology to the private sector.

Review of Grouper Hatchery Technology
Successful larviculture of groupers has been constrained by generally poor, and irregular, survival. The principal constraints to successful larviculture are: the small gape of the larvae and hence their requirement for small prey at first feed; and the occurrence of high mortality at various stages through the larval rearing phase. This document, prepared by Dr. Mike Rimmer of the Queensland Department of Primary Industry provides a nice review grouper larviculture technology, and summarises the current status of this technology.