Dwindling fish catch: Is aquaculture the answer?
By Henrylito D. Tacio, Special Correspondent
The Manila Times
December 10, 2002
DAVAO CITY - PHILIPPINES — Give man a fish, so goes a Chinese saying, and he will eat fish for a day. Teach him how to fish, and he will fish for his lifetime.
“If we don’t watch out, this adage may soon become obsolete,” deplores Dr. Warlito Laquihon, former associate director of the Mindanao Baptist Rural Life Center. “We are fishing our waters to the limit.”
Fishing accounts for only about one percent of the global economy. But on a regional basis, marine fishing contributes enormously to human survival.
In Asia, for instance, more than one billion people rely on fish as their main source of animal protein. Dr. Veravat Hongskul, when he was still the regional fishery officer of the Food and Agriculture Organization, pointed this out: “While fish is not an important source of calories in the human diet, it does have an important role in food supply of many communities, especially in the developing world.”
He said fish contributes animal protein to the human diet. “Fish protein is generally recognized as a valuable ingredient in a balanced diet,” Dr. Hongskul maintains. “It is of high biological value and contains essential amino acids not normally found in staple food. Fish oil also contains essential fatty acids, which are necessary for the proper development of the brain and the body. Where staple food are available, a small quantity to increasing consumption by improving the over-all palatability of the food and add to its nutritive value.”
Worldwide, about 200 million people depend on fishing for their livelihoods, and fishing has been termed as “the employer of last resort” in the developing world — an occupation where there are no other options.
Unfortunately, the coastal and ocean fisheries are in serious decline. In Southeast Asia, “nearly all waters within 15 kilometers of shore are considered overfished,” deplores Dr. Edgardo Gomez, director of the Marine Science Institute of the University of the Philippines.
Peter Weber, a staff member of the Washington-based Worldwatch Institute, agrees. “Overfishing is the primary cause of dwindling fish population,” he writes in his report, “Net Loss: Fish, Jobs, and the Marine Environment.”
But a glimmer of hope surfaced with the recent popularity of aquaculture.
Between 1987 and 1997, global production of farmed fish and shellfish (collectively called “fish”) more than doubled in weight and value, as did its contribution to world fish supplies. Fish produced from farming activities currently accounts for over one-quarter of all fish directly consumed by humans.
“As the human population continues to expand beyond six billion, its reliance on farmed fish production as an important source of protein will also increase,” reports Dr. Rosamond Naylor, one of the authors of an article that examined the effect of aquaculture on world fish supplies, which appears in Nature.
In Asia, aquaculture has taken a new role in fisheries. Off the coast of the Solomon Islands, cultivation of giant clams has begun in earnest.
If fed properly, the giant clams grow to great proportions and are used for variety of nutritional and practical purposes.
Shellfish is cultivated in sheltered coastal regions that are not subject to intense typhoons. Mussels attach themselves in clusters to ropes suspended from rafts. Culture systems for other aquatic species are being developed. Greasy grouper, seabass, and golden snapper can be raised in net cages.
The production of carp has increased markedly in Asia (mainly China) for local or regional consumption by relatively low-income households. In contrast, increased volumes of salmon, shrimp and other high-valued species have been marketed mainly in industrialized countries.
According to the Nature article, authored by Dr. Naylor, et. al., farmed output and markets for other lower-value species, such as tilapia and milkfish, have increased in both developing and industrialized countries.
Most farmed molluscs are still consumed locally and regionally in China and in other developing and industrialized countries.
One of the key benefits of aquaculture is its potential for reducing pressure on marine fisheries. Yet, for carnivorous species such as shrimp, salmon, trout, seabass, and yellowtail, aquaculture actually increase demands on marine production in order to provide feed for the farmed fish.
Marine scientists say the carnivores require amino acids from other fish for growth, which are provided in the form of high-protein feed pellets made from wild fish. An estimated five kilograms of oceanic fish reduced into fishmeal are required to raise one kilogram of farmed ocean fish or shrimp, representing a large net protein loss.
“By 2010, carnivorous fish on farms could be taking all of the world’s fishmeal, using up needed protein that could otherwise be used for direct human consumption — a redistribution of marine biological wealth from the poor to the rich,” says Anne Platt McGinn, another staff member of Worldwatch Institute.
Further pressure is put on marine ecosystems by aquaculture’s reliance on wild stocks to supply seed. Many aquaculture operations stock wild — caught rather than hatchery-related finfish or shellfish post-larvae. Examples include farming of milkfish in the Philippines and Indonesia, tuna in South Australia, shrimp in south Asia and parts of Latin America and eels in Europe and Japan.
In some cases, aquaculture affects stocks of wild and farmed fish. “In tropical freshwater systems, two-thirds of escaped fish species have become established,” reports McGinn. “In Europe, 30 percent of all exotic aquatic species came originally from displacement by farmed stock, as they have specific territorial behavior that is essential for survival in the wild.”
Movement of stocks for aquaculture purposes can also increase the risk of spreading pathogens. Since the early 1990s, Whitespot and Yellowhead viruses have caused catastrophic, multimillion-dollar crop losses in shrimp farms across Asia. In Europe, serious epidemics of furunculosis and Gyrodactylus salaries in stocks of Atlantic salmon have been linked to movements of fish for aquaculture and re-stocking.
Hundreds of thousands of hectares of mangroves and coastal wetlands have been transformed into milkfish and shrimp ponds. This transformation results in loss of essential ecosystem services. In southeast Asia, mangrove-dependent species account for roughly one-third of yearly wild fish landings excluding trash fish. Mangroves are also linked closely to habitat conditions of coral reefs and seagrass beds.
There are more environmental problems than what most people know. In the Philippines, extensive culture of fish in pens and cages consume large quantities of wood, usually bamboo, which putrefy after two years. This demand can have some positive effects (additional income and employment, among others) but may also bring localized deforestation. On the other hand, abandoned unserviceable materials used for cages and pens pose obstruction to fishing and navigation and harbors feeds can also help in sedimentation.
By Henrylito D. Tacio, Special Correspondent
The Manila Times
December 10, 2002
DAVAO CITY - PHILIPPINES — Give man a fish, so goes a Chinese saying, and he will eat fish for a day. Teach him how to fish, and he will fish for his lifetime.
“If we don’t watch out, this adage may soon become obsolete,” deplores Dr. Warlito Laquihon, former associate director of the Mindanao Baptist Rural Life Center. “We are fishing our waters to the limit.”
Fishing accounts for only about one percent of the global economy. But on a regional basis, marine fishing contributes enormously to human survival.
In Asia, for instance, more than one billion people rely on fish as their main source of animal protein. Dr. Veravat Hongskul, when he was still the regional fishery officer of the Food and Agriculture Organization, pointed this out: “While fish is not an important source of calories in the human diet, it does have an important role in food supply of many communities, especially in the developing world.”
He said fish contributes animal protein to the human diet. “Fish protein is generally recognized as a valuable ingredient in a balanced diet,” Dr. Hongskul maintains. “It is of high biological value and contains essential amino acids not normally found in staple food. Fish oil also contains essential fatty acids, which are necessary for the proper development of the brain and the body. Where staple food are available, a small quantity to increasing consumption by improving the over-all palatability of the food and add to its nutritive value.”
Worldwide, about 200 million people depend on fishing for their livelihoods, and fishing has been termed as “the employer of last resort” in the developing world — an occupation where there are no other options.
Unfortunately, the coastal and ocean fisheries are in serious decline. In Southeast Asia, “nearly all waters within 15 kilometers of shore are considered overfished,” deplores Dr. Edgardo Gomez, director of the Marine Science Institute of the University of the Philippines.
Peter Weber, a staff member of the Washington-based Worldwatch Institute, agrees. “Overfishing is the primary cause of dwindling fish population,” he writes in his report, “Net Loss: Fish, Jobs, and the Marine Environment.”
But a glimmer of hope surfaced with the recent popularity of aquaculture.
Between 1987 and 1997, global production of farmed fish and shellfish (collectively called “fish”) more than doubled in weight and value, as did its contribution to world fish supplies. Fish produced from farming activities currently accounts for over one-quarter of all fish directly consumed by humans.
“As the human population continues to expand beyond six billion, its reliance on farmed fish production as an important source of protein will also increase,” reports Dr. Rosamond Naylor, one of the authors of an article that examined the effect of aquaculture on world fish supplies, which appears in Nature.
In Asia, aquaculture has taken a new role in fisheries. Off the coast of the Solomon Islands, cultivation of giant clams has begun in earnest.
If fed properly, the giant clams grow to great proportions and are used for variety of nutritional and practical purposes.
Shellfish is cultivated in sheltered coastal regions that are not subject to intense typhoons. Mussels attach themselves in clusters to ropes suspended from rafts. Culture systems for other aquatic species are being developed. Greasy grouper, seabass, and golden snapper can be raised in net cages.
The production of carp has increased markedly in Asia (mainly China) for local or regional consumption by relatively low-income households. In contrast, increased volumes of salmon, shrimp and other high-valued species have been marketed mainly in industrialized countries.
According to the Nature article, authored by Dr. Naylor, et. al., farmed output and markets for other lower-value species, such as tilapia and milkfish, have increased in both developing and industrialized countries.
Most farmed molluscs are still consumed locally and regionally in China and in other developing and industrialized countries.
One of the key benefits of aquaculture is its potential for reducing pressure on marine fisheries. Yet, for carnivorous species such as shrimp, salmon, trout, seabass, and yellowtail, aquaculture actually increase demands on marine production in order to provide feed for the farmed fish.
Marine scientists say the carnivores require amino acids from other fish for growth, which are provided in the form of high-protein feed pellets made from wild fish. An estimated five kilograms of oceanic fish reduced into fishmeal are required to raise one kilogram of farmed ocean fish or shrimp, representing a large net protein loss.
“By 2010, carnivorous fish on farms could be taking all of the world’s fishmeal, using up needed protein that could otherwise be used for direct human consumption — a redistribution of marine biological wealth from the poor to the rich,” says Anne Platt McGinn, another staff member of Worldwatch Institute.
Further pressure is put on marine ecosystems by aquaculture’s reliance on wild stocks to supply seed. Many aquaculture operations stock wild — caught rather than hatchery-related finfish or shellfish post-larvae. Examples include farming of milkfish in the Philippines and Indonesia, tuna in South Australia, shrimp in south Asia and parts of Latin America and eels in Europe and Japan.
In some cases, aquaculture affects stocks of wild and farmed fish. “In tropical freshwater systems, two-thirds of escaped fish species have become established,” reports McGinn. “In Europe, 30 percent of all exotic aquatic species came originally from displacement by farmed stock, as they have specific territorial behavior that is essential for survival in the wild.”
Movement of stocks for aquaculture purposes can also increase the risk of spreading pathogens. Since the early 1990s, Whitespot and Yellowhead viruses have caused catastrophic, multimillion-dollar crop losses in shrimp farms across Asia. In Europe, serious epidemics of furunculosis and Gyrodactylus salaries in stocks of Atlantic salmon have been linked to movements of fish for aquaculture and re-stocking.
Hundreds of thousands of hectares of mangroves and coastal wetlands have been transformed into milkfish and shrimp ponds. This transformation results in loss of essential ecosystem services. In southeast Asia, mangrove-dependent species account for roughly one-third of yearly wild fish landings excluding trash fish. Mangroves are also linked closely to habitat conditions of coral reefs and seagrass beds.
There are more environmental problems than what most people know. In the Philippines, extensive culture of fish in pens and cages consume large quantities of wood, usually bamboo, which putrefy after two years. This demand can have some positive effects (additional income and employment, among others) but may also bring localized deforestation. On the other hand, abandoned unserviceable materials used for cages and pens pose obstruction to fishing and navigation and harbors feeds can also help in sedimentation.
